ADAPTIVE HYBRIDIZED INTERIOR PENALTY DISCONTINUOUS GALERKIN METHODS FOR H(CURL)-ELLIPTIC PROBLEMS
|
|
- Julie Wade
- 5 years ago
- Views:
Transcription
1 ADAPTIVE HYBRIDIZED INTERIOR PENALTY DISCONTINUOUS GALERKIN METHODS OR HCURL-ELLIPTIC PROBLEMS C. CARSTENSEN, R. H. W. HOPPE, N. SHARMA, AND T. WARBURTON Abstract. We develop and analyze an adaptive hybridized Interior Penalty Discontinuous Galerkin IPDG-H method for Hcurl- elliptic boundary value problems in 2D or 3D arising from a semi-discretization of the eddy currents equations. The method can be derived from a mixed formulation of the given boundary value problem and involves a Lagrange multiplier that is an approximation of the tangential traces of the primal variable on the interfaces of the underlying triangulation of the computational domain. It is shown that the IPDG-H technique can be equivalently formulated and thus implemented as a mortar method. The mesh adaptation is based on a residual-type a posteriori error estimator consisting of element and face residuals. Within a unified framework for adaptive finite element methods, we prove the reliability of the estimator up to a consistency error. The performance of the adaptive symmetric IPDG-H method is documented by numerical results for representative test examples in 2D. Key words. adaptive hybridized Interior Penalty Discontinuous Galerkin method, a posteriori error analysis, Hcurl-elliptic boundary value problems, semi-discrete eddy currents equations AMS subject classifications. 651, 65N3 1. Introduction. Discontinuous Galerkin DG methods are widely used algorithmic schemes for the numerical solution of partial differential equations PDE. or a comprehensive description, we refer to the survey article [24] and the references therein. As far as elliptic boundary value problems are concerned, DG methods can be derived from a primal-dual mixed formulation using local approximations of the primal and dual variables by polynomial scalar and vector-valued functions and appropriately designed numerical fluxes. Among the most popular schemes are Interior Penalty DG IPDG and Local DG LDG methods which have been analyzed by means of a priori estimates of the global discretization, e.g., in [3, 5, 23, 39]. or Hcurl-elliptic boundary value problems arising from a semi-discretization of the eddy currents equations, symmetric IPDG methods have been studied in [36]. The time-harmonic Maxwell equations have been addressed in [46]. On the other hand, the a posteriori error analysis and application of adaptive finite element methods EM for the efficient numerical solution of boundary and initialboundary value problems for PDE has reached some state of maturity as documented by a series of monographs. There exist several concepts including residual and hierarchical type estimators, error estimators that are based on local averaging, the so-called goal oriented dual weighted approach, and functional type error majorants cf. [2, 6, 7, 3, 44, 49] and the references therein. A posteriori error estimators for DG methods applied to second order elliptic boundary value problems have been developed and analyzed in [1, 11, 18, 38, 4, 47]. In particular, a convergence analysis of adaptive symmetric IPDG methods has been provided in [12, 34] and [41]. Residualand hierarchical-type a posteriori error estimator for Hcurl-elliptic problems have Dep. of Math., Humboldt Universität zu Berlin, D-199 Berlin, Germany Dep. of Comput. Sci. Eng., Yonsei University, Seoul , Korea Dep. of Math., Univ. of Houston, Houston, TX , U.S.A. Inst. of Math., Univ. of Augsburg, D Augsburg, Germany CAAM, Rice Univ., Houston, TX , U.S.A. The first author has been supported by the German National Science oundation DG within the Research Center MATHEON and by the WCU program through KOSE R The other authors acknowledge support by the NS grant DMS
2 been studied in [8, 9, 1, 2, 37]. A convergence analysis for residual estimators has been developed in [19] for 2D and in [35] for 3D problems. rom a computational point of view, DG methods suffer from a relatively huge amount of globally coupled degrees of freedom DO compared to standard EM. Hybridization is a technique that gives rise to a significant reduction of the globally coupled DO. It has been introduced for mixed EM in [31] and further studied in [4, 13, 15, 25, 26]. Adaptive mixed hybrid methods on the basis of reliable a posteriori error estimators have been considered in [14, 45] and [5]. or DG methods, a survey of hybridized DG DG-H methods has been provided in [26], whereas a unified analysis has been developed in [28]. However, adaptive DG-H methods have not yet been investigated. In this paper, we will derive and analyze a residual-type a posteriori error estimator for hybridized symmetric IPDG IPDG-H methods applied to Hcurl-elliptic boundary value problems in 3D. The analysis will be carried out within a unified framework provided for adaptive finite element approximations in [17, 18, 2, 21, 22]. The paper is organized as follows: In Section 2, we introduce some basic notation and present the class of Hcurl-elliptic boundary value problems to be approximated by symmetric IPDG-H methods. Section 3 deals with the development of symmetric IPDG-H methods based on a mixed formulation of the elliptic boundary value problems. We establish its relationship with mortar techniques which allows the implementation as a mortar method. In section 4, we present the residual-type a posteriori error estimator and prove its reliability. inally, in section 5, we provide a detailed documentation of numerical results to illustrate the performance of the symmetric IPDG-H methods. 2. Basic Notations. Let Ω R 3 be a simply connected polyhedral domain with boundary Γ = Ω such that Γ = Γ D Γ N, Γ D Γ N =. We denote by DΩ the space of all infinitely often differentiable functions with compact support in Ω and by D Ω its dual space referring to <, > as the dual pairing between D Ω and DΩ. We further adopt standard notation from Lebesgue and Sobolev space theory. In particular, for a subset D Ω, we refer to L 2 D and L 2 D as the Hilbert spaces of scalar and vector-valued square integrable functions with inner products,,d and associated norms,d, respectively. urther, we denote by H 1 D the Sobolev space of square integrable functions with square integrable weak derivatives equipped with the inner product, 1,D and norm 1,D. or Σ D, we refer to H 1/2 Σ as the space of traces v Σ of functions v H 1 D on Σ. We set H,Σ 1 D := {v H1 Ω v Σ = } and refer to H Σ D as the associated dual space. or a simply connected polyhedral domain Ω with boundary Γ = Ω which can be split into J relatively open faces Γ 1,..., Γ J with Γ = J j=1 Γ j, we refer to Hcurl; Ω as the Hilbert space Hcurl; Ω := {u L 2 Ω curl u L 2 Ω}, equipped with the inner product u, v curl,ω := u, v,ω curl u, curl v,ω and the associated norm curl,ω. We further refer to Hcurl ; Ω as the subspace of irrotational vector fields. The space Hdiv; Ω is defined by Hdiv; Ω := { q L 2 Ω div q L 2 Ω} which is a Hilbert space with respect to the inner product u, v div,ω := u, v,ω div u, div v,ω and the associated norm div,ω. or vector fields u C Ω 3 := {u Ω u C R 3 }, the normal component trace reads η n u Γj := n Γj u Γj, j = 1,..., J with the exterior unit normal vector n Γj on Γ j. The normal component trace mapping can be extended by continuity to a surjective, continuous linear mapping η n : Hdiv; Ω H /2 Γ cf. [32]; Thm We define H div; Ω as the subspace of vector fields with vanishing normal components on 2
3 Γ. In order to study the traces of vector fields q Hcurl; Ω, following [16], we introduce the spaces L 2 tγ := {u L 2 Ω η n u = }, H 1/2 Γ := {u L 2 tγ u Γj H 1/2 Γ j for all j = 1,..., J}. 6 t j t k n j n k t jk Γ j Γ k ig Two adjacent faces Γ j, Γ k with common edge E jk or Γ j, Γ k Γ with j k and E jk := Γ j Γ k E h, the set of edges, we denote by t j and t k the tangential unit vectors along Γ j and Γ k and by t jk the unit vector parallel to E jk such that Γ j is spanned by t j, t jk and Γ k by t k, t jk cf. igure 2.1. Let J := {j, k {1,..., J} 2 Γ j Γ k = E jk E h } and define H 1/2 Γ := {u H 1/2 Γ t jk u j Ejk = t jk u k Ejk for j, k J }, H 1/2 Γ := {u H1/2 Γ t j u j Ejk = t k u k Ejk for j, k J }. We refer to H /2 Γ and H /2 Γ as the dual spaces of H 1/2 Γ and H 1/2 Γ with L 2 tγ as the pivot space. or u D Ω 3 we further define the tangential trace mapping γ t Γj := u n Γj Γj, j = 1,..., J, and the tangential components trace π t Γj := n Γj u n Γj Γj, j = 1,..., J. Moreover, for a smooth function u D Ω we define the tangential gradient operator Γ = grad Γ as the tangential components trace of the gradient operator, i.e., Γ u Γj := Γj u = π t,j u = n Γj u n Γj, j = 1,..., J, which leads to a continuous linear mapping Γ : H 3/2 Γ H 1/2 Γ cf. [16]. The tangential divergence operator div Γ : H /2 Γ H 3/2 Γ is defined, with the respective dual pairings,, as the adjoint operator of Γ, i.e., div Γ u, v = u, Γ v, v H 3/2 Γ, u H /2 Γ. inally, for u C Ω we define the tangential curl operator curl τ as the tangential trace of the gradient operator curl τ u Γj = curl Γj u = γ t,j u = u n j for j = 1,..., J. 2.1 The vectorial tangential curl operator is a linear continuous mapping The scalar tangential curl operator curl τ : H 3/2 Γ H 1/2 Γ. curl τ : H /2 Γ H 3/2 Γ is defined as the adjoint of the vectorial tangential curl operator via curl τ, i.e., < curl τ u, v > = < u, curl Γ v > for all v H 3/2 Γ and u H /2 Γ. 3
4 The range spaces of the tangential trace mapping γ t and the tangential components trace mapping π t on Hcurl; Ω can be characterized by means of the spaces H /2 div Γ, Γ := { λ H /2 Γ div Γ λ H /2 Γ }, H /2 curl Γ, Γ := { λ H /2 Γ curl Γ λ H /2 Γ }, which are dual to each other with respect to the pivot space L 2 tγ. We refer to /2,divΓ,Γ and /2,curlΓ,Γ as the respective norms and denote by, /2,Γ the dual pairing see, e.g., [16] for details. It can be shown that the tangential trace mapping is a continuous linear mapping γ t : Hcurl; Ω H /2 div Γ, Γ, whereas the tangential components trace mapping is a continuous linear mapping π t : Hcurl; Ω H /2 curl Γ, Γ. The previous results imply that the tangential divergence of the tangential trace and the scalar tangential curl of the tangential components trace coincide: or u Hcurl; Ω it holds div Γ u n = curl Γ n u n = n curl u. We define H curl; Ω as the subspace of Hcurl; Ω with vanishing tangential traces on Γ. Given a polyhedral domain Ω R 3 with boundary Γ = Ω such that Γ = Γ D Γ N, Γ D Γ N =, we denote by T H Ω a shape-regular simplicial triangulation of Ω that aligns with Γ D and Γ N. We refer to H Ω as the set of interior faces = T T, T ± T H Ω, and to H Σ as the set of faces located on the boundary Σ Γ, while H Ω := H Ω H Γ is the set of all faces. urther, E H Σ stands for the set of edges on Σ. We denote by h T and h the diameter of an element T T H Ω and a face H Ω, respectively. or two quantities A, B R, we use the notation A B, if there exists a constant C R, independent of the mesh size of the triangulation T H Ω, such that A CB. We refer to Nd 1 Ω; T H Ω := {v H Hcurl; Ω v H T ND 1 T, T T H Ω} as the curl-conforming edge element space, where ND 1 T stands for the lowest order edge element of Nédélec s first family [43], and to Nd 1,Γ D Ω; T H Ω := {v H Nd 1 Ω; T H Ω γ t v H = on Γ D } as its subspace of vanishing tangential trace components on Γ D. or vector fields v H Hcurl; T, we denote by curl,h,ω the meshdependent norm 1/2 v H curl,h,ω := v H 2,T curl v H 2,T. Moreover, for such vector fields we set v ± H := v H T± along = T T H Ω and define { v {v H } := H v H /2, HΩ, v H, H Γ { v [v H ] := H v H, HΩ, H Γ 4
5 as the averages and jumps of v H across the interior faces of the triangulation. or scalar functions v H L 2 Ω, the averages {v H } and jumps [v H ] are defined analogously. The class of Hcurl-elliptic boundary value problems to be approximated by IPDG-H methods is of the form curl µ curl u σ u = f in Ω, 2.2a γ t u = g 1 on Γ D, 2.2b π t µ curl u = g 2 on Γ N. 2.2c We assume that f L 2 Ω, g 1 L 2 Γ D, and g 2 Hcurl Γ N ; Γ N. We further suppose that µ is a symmetric, uniformly positive definite matrix-valued function µ = µx, x Ω, and that σ is a scalar nonnegative function σ = σx, x Ω, that are elementwise constant with respect to a given coarse simplicial triangulation T H Ω of the computational domain. We note that the subsequent analysis also applies to Hcurl-elliptic problems in 2D as given by curl µ curl u σ u = f in Ω, 2.3a t ΓD u = g 1 on Γ D, 2.3b µ curl u = g 2 on Γ N, 2.3c where curl u = u 2 / x 1 u 1 / x 2 for u = u 1, u 2 T, whereas curl u = u/ x 2, u/ x 1 T for a scalar function u. Moreover, t ΓD stands for the tangential unit vector on the Dirichlet part Γ D of the boundary. The data f, g 1 and g 2 have to be chosen accordingly. We will develop the IPDG-H method and perform the a posteriori error analysis only in the 3D case. The necessary modifications for 2D problems are straightforward. 3. Hybridized IPDG Methods. A mixed formulation of 2.2a-2.2c can be derived by introducing p := µ curl u as an additional variable. Setting V := {v Hcurl; Ω γ t u = g 1 on Γ D }, Q := L 2 Ω, 3.1 V := {v Hcurl; Ω γ t u = on Γ D }, it amounts to the computation of u, p V Q with ap, q bu, q = l 1 q for all q Q, 3.2a bv, p cu, v = l 2 v for all v V. 3.2b 5
6 The bilinear forms a, b and c and the functionals l 1 Q, l 2 V are given by ap, q := µ p q dx, 3.3a Ω Ω bu, q := curl u q dx, cu, v := Ω σ u v dx, l 1 q :=, l 2 v := f v dx Ω 3.3b 3.3c 3.3d Γ N g 2 γ t v dτ. 3.3e The operator-theoretic framework involves the operator A : V Q V Q defined, for all u, p V Q and all v, q V Q by Au, pv, q := ap, q bu, q bv, p cu, v. 3.4 Then, the system 3.2a-3.2b can be written in compact form as where lv, q := l 1 q l 2 v for all v, q V Q. Au, p = l, 3.5 Theorem 3.1. Under the assumptions on the data of 2.2a-2.2c, A is a continuous, bijective linear operator. Hence, for any l 1, l 2 Q V, the system 3.2a-3.2b admits a unique solution u, p V Q which continuously depends on the data, namely u, p V Q l 1 Q l 2 V. 3.6 Proof. The mapping properties are straightforward. If g 1, there exists a unique u g1 V such that for all v V cf., e.g., [42] Au g1, v, µ curl v = Ω µ curl u g1 curl v σu g1 v dx =, and hence, we may restrict ourselves to the case of A : V Q V Q. Now, for any u, p V Q we have Au, p3u, 2p µ curl u = A3u, 2p µ curl uu, p = 2µ p 2 L 2 Ω 3σ u 2 L 2 Ω µ curl u 2 L 2 Ω. This implies the inf-sup condition and the remaining degeneracy condition which implies bijectivity. Given a simplicial triangulation T H Ω, DG methods are based on the approximation of the vector field u and p by elementwise polynomials, thus giving rise to the 6
7 finite dimensional function spaces V H := {v H L 2 Ω v H T Π k T, T T H Ω, 3.7a γ t v H = g H,1 on H Γ D }, Q H := {q H L 2 Ω q H T Π k T, T T H Ω}. 3.7b Here and in the sequel, g H,1 Π k, H Γ D is some approximation of g 1 and Π k T, T T H Ω, as well as Π k, H Ω, stand for the sets of vector-valued functions whose components are polynomials of degree at most k N. DG methods amount to the computation of p H, u H Q H V H with a H p H, q H b H u H, q H d H û H, q H = l 1 H q H for all q H Q H, b H v H, p H d H v H, ˆp H c H u H, v H = l 2 H v H for all v H V H. 3.8a 3.8b Here and throughout, û H, ˆp H are appropriate numerical flux functions and the meshdependent bilinear forms a H, b H, c H, and d H are defined by means of a H p H, q H := µp H q H dx, 3.9a The functionals l 1 H b H u H, q H := c H u H, v H := d H u H, q H := T T T H Ω and l2 H are given by curl u H q H dx, σu H v H dx, 3.9b 3.9c γ t u H, π t q H. 3.9d l 1 H q H :=, l 2 H v H := T f v H dx H Γ N g 2 γ t v H dτ. 3.1a 3.1b In case of symmetric Interior Penalty Discontinuous Galerkin IPDG methods, the numerical fluxes read γ t û H := π t ˆp H := { {γt u H }, H Ω, H Γ { {πt µ curl u H } α h [γ tu H ], H Ω, H Γ 3.11a 3.11b with a suitable penalty parameter α >. The choice q H := µ curl v H in 3.8a and 3.11a,3.11b allow the elimination of p H from 3.8a,3.8b. This results in the following standard form of the symmetric IPDG method: ind u H V H such that a IP u H, v H = l IP v H for all v H V H
8 Here and in the sequel, the bilinear form a IP and the functional l IP read a IP u H, v H := µ curl u H curl v H σu H v H dx H Ω α H Ω l IP v H := T {π t µ curl u H } [γ t v H ] {γ t u H } [π t µ curl v H ] h T [γ t u H ] [γ t v H ]dτ, f v H dx H Γ N g 2 γ t v H dτ. 3.13a dτ 3.13b The idea of hybridization is to enforce the continuity of the tangential component traces of p H across the interior edges of the triangulation by a piecewise polynomial Lagrange multiplier which is an approximation of the tangential traces of u. or this purpose, we introduce the multiplier space M H := {µ H L 2 H Ω µ H Π k, H Ω} Choosing a numerical flux function ˆp H, not necessarily the same as in 3.11b, the IPDG-H method is to find p H, u H, λ H Q H V H M H with a H p H, q h b H u H, q H d H λ H, q H = l 1 H q H for all q H Q H, 3.15a b H v H, p H d H v H, ˆp H c H u H, v H = l 2 H v H for all v H V H, 3.15b d H µ H, ˆp H = for all µ H M H. 3.15c In IPDG-H methods, the penalty parameter α is typically chosen elementwise, i.e., α T = α T, T T H Ω, so that on H Ω with = T T, T ± T H Ω, we have to distinguish between α := α T and α := α T. The advantage of hybridized methods is that the primal and dual variables u H and p H can be eliminated from 3.15a-3.15c which results in a global variational problem for the Lagrange multiplier λ H M H of the form a S H λ H, µ H = l S H µ H for all µ H M H Once λ H M H has been computed, the primal and dual variables can be computed by the solution of low-dimensional, local problems. To this end, following the unified framework from [28], we set { { uh on T \ Γ λ H = D, ḡ on T Γ H,1 = D { ḡ H,2 = on T \ Γ N g H,2 on T Γ N on T \ Γ D g H,1 on T Γ D, with an approximation g H,2 Π k, H Γ N, of g 2. We define S p f, S u f Π k T 2, S p λ H, S u λ H Π k T 2, S p g H,1, S u g H,1 Π k T 2, S p g H,2, S u g H,2 Π k T 2 8
9 as the solutions of the local problems µ S p f curl S u f = in T, 3.17a curl S p f σ S u f = f in T, γ t S u f = on T, µ S p λ H curl S u λ H = in T, 3.17b curl S p λ H σ S u λ H = in T, γ t S u λ H = λ H on T, µ S p ḡ H,1 curl S u ḡ H,1 = in T, 3.17c curl S p ḡ H,1 σ S u ḡ H,1 = in T, γ t S u ḡ H,1 = ḡ H,1 on T, µ S p ḡ H,2 curl S u ḡ H,2 = in T, 3.17d curl S p ḡ H,2 σ S u ḡ H,2 = in T, π t S u ḡ H,2 = ḡ H,2 on T. The numerical flux π t ˆp H is given by means of local numerical fluxes π t ˆp H = Ŝpf Ŝpλ H Ŝpḡ H,1 Ŝpḡ H, In particular, for the IPDG-H method 3.15a-3.15c we choose Ŝ p f = { πt µ curl S u f α T h γ ts u f on H Ω Γ D, π t µ curl S u f α T h π tµ curl S u f on H Γ N, Ŝ p λ H = Ŝ p ḡ H,i = π t µ curl S u λ H α T h γ ts u λ H λ H on H Ω Γ D, π t µ curl S u λ H α T h π tµ curl S u λ H λ H on H Γ N, π t µ curl S u ḡ H,i α T h γ ts u ḡ H,i ḡ H,i on H Ω Γ D, π t µ curl S u ḡ H,i α T h π tµ curl S u ḡ H,i ḡ H,i on H Γ N. 3.19a 3.19b 3.19c or sufficiently large α T, T T H Ω, both the local problems 3.17a-3.17d and the global variational problem 3.16 have unique solutions which can be shown along the same lines of proof as in [28] for standard second order elliptic boundary value problems. If λ H M H solves 3.16, then defines the solution of 3.15a-3.15c. p H = S p f S p λ H S p ḡ H,1 S p ḡ H,2, 3.2 u H = S u f S u λ H S u ḡ H,1 S u ḡ H,2 Theorem 3.2. Assume that the numerical flux ˆp H is given by 3.18 and that p H, u H, λ H is the solution of 3.15a-3.15c. Then, the numerical flux ˆp H and the 9
10 multiplier λ H satisfy ᾱ α π t µ curl u H α π t µ curl u H π t ˆp H := α α h [γ tu H ] on H Ω, on H Γ D, on H Γ N, ᾱ α γ t u H α γ t u H λ H = h [π t µ curl u H ] on H Ω, α T h π t µ curl u H on H Γ D, α T h π t µ curl u H on H Γ N, 3.21a 3.21b where ᾱ := α α on = T T for T ± T H Ω. Proof. Let H Ω. If we use 3.19a-3.19c and 3.2 in 3.18, we obtain π t ˆp H = π t µ curl u H α T h Hence, observing 3.17b, it follows that [π t ˆp H ] = [π t µ curl u H ] α h γ tu H γ t u H γ t S u λ H on. α h γ tu H 3.22 α α h λ H. The specification 3.14 of the multiplier space M H and equation 3.15c imply [π t ˆp H ] =. This results in 3.21b due to On the other hand, π t ˆp ± H = π tp ± H α ±h γ t u ± H λ H We deduce 3.21a by inserting 3.21b into The proof of 3.21a,3.21b for H Γ D and H Γ N follows from similar arguments. The representation 3.21b of the Lagrange multiplier λ H shows that it provides an approximation of the tangential trace on the interfaces H Ω which reminds of mortar methods for Hcurl-elliptic problems cf., e.g., [2, 51]. Indeed, the IPDG- H method 3.15a-3.15c can be equivalently formulated as a mortar method. To see this, choose q H = µ curl u H in 3.15a and the numerical flux ˆp H in 3.15a according to 3.21b. Then, by elimination of p H, λ H := λ H ᾱ α γ t u H α γ t u H satisfies ã H u H, v H b H λ H, v H = l 2 H v H for all v H V H, 3.24 bh µ H, u H d H λ H, µ H = for all µ H M H. 1
11 Here and throughout the following, the bilinear forms ã H, b H and d H read ã H u H, v H := T Ω T Ω T Ω T Γ bh λ H, v H := d H λ H, µ H := T µ curl u H curl v H σu H v H dx ᾱ α T π t µ curl u H γ t v H dτ ᾱ α T α T h γ tu H γ t v H dτ ᾱ α T γ t u H π tµ curl v H dτ α T h π t µ curl u H π t µ curl v H dτ, H Ω H Ω λ H [π t µ curl v H ] dτ, ᾱ h λ H µ H dτ. The variational system 3.24 represents a symmetric saddle point problem which can be solved as in the standard mortar approach. Denoting by ÃH, B H, D H the matrices and by b H the vector associated with the bilinear forms and the right-hand side in the first equation of 3.24, the algebraic form of the saddle point problem is ÃH BH uh B T H D H λ H = bh Static condensation of u H results in the equivalent Schur complement system DH B T HÃ H B H λh = B T HÃ H b H A posteriori error analysis. The residual a posteriori error estimator for the symmetric IPDG-H method 3.15a-3.15c is given by η := H Γ N They consist of the element residuals ηt,1 2 ηt,2 2 ηt,3 2 η 2,3 η 2,4 1/2. H Ω η,1 2 η, η T,1 := µp H curl u H,T for all T T H Ω, 4.2a η T,2 := h T f curl p H σu H,T for all T T H Ω, 4.2b η T,3 := h T f σu H,T for all T T H Ω, 4.2c 11
12 and the face residuals η,1 := h 1/2 [π t p H ], for all H Ω, 4.3a η,2 := h 1/2 n [f σu H ], for all H Ω, 4.3b η,3 := h 1/2 g 2 π t p H, for all H Γ N, 4.3c η,4 := h 1/2 n f σu H, for all H Γ N. 4.3d The nonconformity of the symmetric IPDG-H method results in some consistency error ξ := 1/2 min u H ṽ H 2,T curl u H ṽ H 2,T 4.4 ṽ H V with the unique minimizer ũ H V of 4.4 and ξ 2 = u H ũ H 2,Ω curlu H ũ H 2,Ω. Theorem 4.1. Let p, u Q V and p H, u H, λ H Q H V H M H be the solutions of 3.5 and 3.15a-3.15c, let η and ξ be the residual error estimator and the consistency error of 4.1 and 4.4. Then, u, p u H, p H := p p H 2 Q u u H 2 curl,h,ω 1/2 η ξ. 4.5 We will provide the proof of Theorem 4.1 by a series of lemmas. We assume p H, ũ H Q V to be some approximation of the solution p, u Q V of the mixed problem 3.5 obtained by means of the solution p H, u H, λ H of the symmetric IPDG-H method 3.15a-3.15c. It is an immediate consequence of Theorem 3.1 that the error p p H, u ũ H satisfies p p H, u ũ H Q V Res 1 Q Res 2 V 4.6 with residuals Res 1 Q and Res 2 V, Res 1 q := l 1 q a p H, q bũ H, q for q Q, 4.7a Res 2 v := l 2 v bv, p H cũ H, v for v V. 4.7b Lemma 4.1. Let p H, u H, λ H Q H V H M H be the solution of 3.15a- 3.15c with the numerical flux ˆp H from The choice of p H = p H and of ũ H V as the unique minimizer of 4.4 imply Res 1 Q η 2 T,1 1/2 ξ. 4.8 Proof. With the L 2 -projection q H = P QH q of q Q onto Q H, we have q H,Ω q,ω and Res 1 q = Res 1 q P QH q Res 1 P QH q
13 In view of 4.7a and 3.3a,3.3b,3.3d, it follows that Res 1 q P QH q = T curl u H µ p H q P QH q dx T curl ũ H u H q P QH q dx. Straightforward estimation and q P QH q,ω q Q yield Res 1 q P QH q curl ũ H u H 2,T η 2 T,1 1/2 ξ q Q. curl u H µ p H 2,T 1/ /2 q P Q q 2,T Similar arguments for the last term in 4.9 and P QH q,ω q,ω reveal Res 1 P QH q 1/2 curl u H µ p H 2,T 1/2 PQH q,ω 4.11 curlû H u H 2,T 1/2 PQH q,ω η 2 T,1 1/2 ξ q Q. The combination of 4.1 and 4.11 concludes the proof. Lemma 4.2. or p H = p H and some approximation ũ H V H let the residual Res 2 of 4.7b satisfy Nd 1 ;Γ D Ω; T H Ω Ker Res Then, it holds Res 2 V ηt,2 2 ηt,3 2 η,1 2 η,2 2 H Ω 1/2 η,3 2 η,4 2 ξ. H Γ N 4.13 Proof. Given any v V, Theorem 1 in [48] shows that there exist v H Nd 1 ;Γ D Ω; T H Ω, ϕ H 1,Γ D Ω, and z H 1,Γ D Ω 3 such that v v H = ϕ z
14 and with appropriate patches ω T and ω ϕ,t h T v curl;ωt for T T H Ω, 4.15a ϕ,t v curl;ωt for T T H Ω, 4.15b h /2 ϕ, v curl;ω for H Ω Γ N, 4.15c z,t h T v curl;ω for T T H Ω, 4.15d h /2 γ t z, v,ω for H Ω Γ N. 4.15e It is a consequence of 4.12 and 4.14 that Res 2 v = Res 2 v v h = Res 2 ϕ Res 2 z The first term on the right-hand side in 4.16 reads Res 2 ϕ = T T σu H ϕ dx f ϕ dx An application of Green s formula gives T T f σu H ϕ dx = H Ω n [f σu H ] ϕ dτ H Γ N T g 2 γ t ϕ dτ 4.17 σũ H u H ϕ dx. H Γ N f σu H ϕ dx 4.18 n f σu H ϕ dτ. Since γ t ϕ = curl ϕ on H Γ N, a further application of Stokes formula yields H Γ N = H Γ N g 2 γ t ϕ dτ = E E H Γ N E curl g 2 ϕ dτ t E g 2 ϕ ds. H Γ N E E H Γ N E g 2 curl ϕ dτ 4.19 t E {g 2 } [ϕ] t E [g 2 ]{ϕ} ds Since g 2 Hcurl Γ N ; Γ N, we have curl g 2 =, H Γ N. Since ϕ H,Γ 1 D Ω, we have ϕ = on E E H Γ N. Consequently, 4.19 yields H Γ N g 2 γ t ϕ dτ =
15 With 4.18 and 4.2, 4.17 leads to Res 2 ϕ H Ω H Γ N h 2 T f σu H 2,T h n [f σu H ] 2, h n f σu H 2, ũ H u H 2,T This and 4.15a-4.15c imply Res 2 ϕ 1/2 1/2 η 2 T,3 H Γ N 1/2 H Ω 1/2 H Γ N ϕ 2,T 1/2. 1/2 η 2,4 h ϕ 2, H Ω 1/2 h 2 T ϕ 2,T 1/2 1/2 h ϕ 2, 1/2 ξ v curl;ω. η 2,2 1/ On the other hand, the second term on the right-hand side of 4.16 reads Res 2 z = f z dx g 2 γ t z dτ 4.22 T T T H Γ N p H curl z dx σũ H u H z dx. T σu H z dx Since [γ t z] = on H Ω, an application of Stokes theorem gives p H curl z dx = curl p H z dx T H Ω This and 4.22 lead to Res 2 z = H Ω T [π t p H ] γ t z dτ T H Γ N f curl p H σu H z dx [π t p H ] γ t z dτ T σũ H u H z dx. 15 H Γ N π t p H γ t z dτ. g 2 π t p H γ t z dτ
16 Hence, Res 2 z is bounded from above by Res 2 z H Ω H Γ N h 2 T f curl p H σu H 2,T h [π t p H ] 2, h g 2 π t p H 2, h 2 T ũ H u H 2,T This and 4.15d,4.15e result in Res 2 z 1/2 H Ω 1/2 1/2 1/2 η 2 T,2 H Γ N h γ tz 2, H Γ N 1/2 η 2,3 1/2 h 2 T z 2,T 1/2 h γ t z 2, h 2 T z 2,T 1/2. H Ω 1/2 ξ v curl;ω. The combination of 4.21 and 4.23 plus 4.16 concludes the proof. Lemma 4.3. or v H Nd p,γ D Ω; T H Ω it holds 1/2 η 2,1 1/ Res 2 v H = c H u H ũ H, v H Proof. We have Res 2 v H = l 2 H v H b H v H, p H c H ũ H, v H 4.25 = l 2 H v H b H v H, p H c H u H, v H c H u H ũ H, v H. Since v H Nd 1,Γ D Ω; T H Ω V H is an admissible test function in 3.15b, it follows that b H v H, p H c H u H, v H = l 2 H v H d H v H, ˆp H Since 3.21a, the last term vanishes The combination of concludes the proof. d H v H, ˆp H = Proof of Theorem 4.1. In view of Lemma 4.2 we define It follows that Res 2 := Res 2 c H u H ũ H, Res 2 V Res 2 V ξ
17 In view of 4.24, we have Nd 1,Γ D Ω; T H Ω Ker Res 2. Hence, Lemma 4.3 with Res 2 replaced by Res 2 yields Res 2 V η 2 T,2 η 2 T,3 H Γ N H Ω η 2,3 η 2,4 1/2. η,1 2 η, As in the case of the symmetric IPDG method cf., e.g., [2, 37], the consistency error admits the upper bound ξ H Ω η 2,5 1/2, η,5 := h /2 [γ t u H ], The combination of 4.8, and the triangle inequality u, p u H, p H u, p ũ H, p H u H ũ H curl,h,ω conclude the proof. 5. Numerical Results The Adaptive Cycle. The adaptive IPDG-H method is realized within an adaptive cycle with the basic steps SOLVE, ESTIMATE, MARK, and REINE. SOLVE stands for the numerical solution of the hybridized IPDG scheme with the mortar approach of section 3 implemented in the nudg code from [33] for the solution of The step ESTIMATE is devoted to the computation of the element residuals η T,i, 1 i 3, and the face residuals η,i, 1 i 4 cf. 4.2a-4.2c and 4.3a-4.3c as the basic constituents of the residual error estimator η cf Moreover, the consistency error ξ cf. 4.4 is estimated by the additional face residuals η,5 according to The following step MARK deals with the marking of elements and faces for refinement by a bulk criterion, also known as Dörfler marking [29]. In particular, given a universal constant < θ < 1, sets M T T H Ω {1, 2, 3} and M H Ω {1, 2, 3, 4, 5} of almost minimal cardinality are determined such that θ η 2 ηt,i 2 η,i T,i M T,i M The bulk criterion 5.1 is implemented by a greedy algorithm. or sufficiently small θ, it is expected that the bulk criterion may yield asymptotic optimal complexity cf., e.g., [12] in case of adaptive IPDG methods for standard second order elliptic boundary value problems. The final step REINE takes care of the practical realization of the adaptive refinement. Elements T T H Ω and faces H Ω such that T, i M T for some 1 i 3 and, i M for some 1 i 5 are refined by bisection Numerical Examples. or the illustration of the performance of the residual a posteriori error estimator we consider two examples of Hcurl-elliptic boundary value problems in 2D from 2.3a-2.3c. Both examples feature solutions in Hcurl; Ω with components in H s Ω for some < s < 1. The first one has an an 17
18 irrotational solution on an L-shaped domain with a singularity at the reentrant corner and the second one exhibits a solenoidal solution on a circle with a cut out wedge having a singularity at the origin. or both problems, the penalty parameters in the IPDG-H method have been chosen according to α ± := κk 1 2 /2 with κ = 1. Example 1: We consider the L-shaped domain Ω :=, 1 2 \[, 1] [, ] with Dirichlet boundary Γ D :=, 1, 1, Neumann boundary Γ N := Γ \ Γ D and data µ = σ = 1. The right-hand sides f, g 1, g 2 in 2.3a-2.3c are chosen such that u = gradr 2/3 sin 2 3 ϕ is the exact solution in polar coordinates. The solution is in Hcurl; Ω H 2/3 ε Ω for any ε > and exhibits a singularity at the reentrant corner. Mesh Level Mesh Level 8 Mesh Level ig Ex. 1: The initial mesh left and the meshes after 8 middle and 18 right adaptive refinement steps k = 4 and Θ =.1..5 k=1.5 k = 4 log u, p u H, p H θ=.1 θ=.3 3 θ=.5 θ =.7 uniform log DO log u, p u H, p H θ=.1 θ=.3 3 θ=.5 θ =.7 uniform log DO ig Ex. 1: The error u, p u H, p H versus the number of degrees of freedom on a logarithmic scale for various θ, k = 1 left and k = 4 right. igure 5.1 shows the initial mesh left and the meshes obtained after 8 middle and 18 right refinement steps of the adaptive algorithm in case k = 4 and θ =.1. We observe a pronounced refinement in a vicinity of the reentrant corner. igure 5.2 displays the global discretization error u, p u H, p H cf. 4.5 as a function of the number of degrees of freedom DO on a logarithmic scale for both uniform refinement and adaptive refinement in case k = 1 left and k = 4 right. The 18
19 results of the adaptive refinement are shown for various values of the constant θ in the bulk criterion 5.1. Both for k = 1 and k = 4 the benefits of adaptive versus uniform refinement can be clearly seen. In case k = 1, we observe a dependence of the convergence rate on the parameter θ which is much less pronounced in case k = 4. According to the theory for IPDG methods applied to standard second order elliptic boundary value problems cf. [12] and the numerical results in [34], we see that optimality is asymptotically achieved for small θ. Example 2: The domain Ω is the unit circle with a cut out wedge see igure 5.3. We assume µ = σ = 1 and Neumann boundary conditions on Γ = Ω. The data f and g 2 are chosen such that u = curlr 4/7 sin 4 7ϕ is the exact solution in polar coordinates. The solution is in Hcurl; Ω H 4/7 ε Ω for any ε > and exhibits a singularity at the origin. We use isoparametric elements for a proper resolution of the curved part of the boundary. Mesh Level Mesh Level 6 Mesh Level ig Ex. 2: The initial mesh left and the meshes after 6 middle and 14 right adaptive refinement steps k = 4 and Θ =.1..5 K=1 k = 4 log u, p u H, p H.5 θ=.1 2 θ=.3 θ=.5 θ=.7 uniform log DO log u, p u H, p H θ=.1 θ=.3 θ=.5 θ =.7 uniform log DO ig Ex. 2: The error u, p u H, p H versus the number of degrees of freedom on a logarithmic scale for various θ, k = 1 left and k = 4 right. As for the previous example, igures 5.3 and 5.4 display the history of the refinement process. We basically observe a similar behavior with asymptotically optimal convergence for small θ. However, in the pre-asymptotic regime, the decrease of the discretization error is less pronounced. The reason is that there are two main sources for the error: the singularity at the origin and the resolution of the curved boundary. Since the error is dominated by the singularity, the greedy algorithm realizing the 19
20 bulk criterion 5.1 picks the corresponding residuals first until those associated with the boundary resolution are taken into account. REERENCES [1] M. Ainsworth, A posteriori error estimation for Discontinuous Galerkin finite element approximation. SIAM J. Numer. Anal. 45, , 27. [2] M. Ainsworth and T. Oden, A Posteriori Error Estimation in inite Element Analysis. Wiley, Chichester, 2. [3] D.N. Arnold, An interior penalty finite element method with discontinuous elements. SIAM J. Numer. Anal. 19, , [4] D.N. Arnold and. Brezzi, Mixed and nonconforming finite element methods: implementation, postprocessing and error estimates. RAIRO Modél. Math. Anal. Numér. 19, 7 32, [5] D.N. Arnold,. Brezzi, B. Cockburn, and D. Marini, Unified analysis of discontinuous Galerkin methods for elliptic problems. SIAM J. Numer. Anal. 39, , 22. [6] I. Babuska and T. Strouboulis, The inite Element Method and its Reliability. Clarendon Press, Oxford, 21. [7] W. Bangerth and R. Rannacher, Adaptive inite Element Methods for Differential Equations. Lectures in Mathematics. ETH-Zürich. Birkhäuser, Basel, 23. [8] R. Beck, P. Deuflhard, R. Hiptmair, R.H.W. Hoppe, and B. Wohlmuth, Adaptive multilevel methods for edge element discretizations of Maxwell s equations. Surveys of Math. in Industry 8, , [9] R. Beck, R. Hiptmair, R.H.W. Hoppe, and B. Wohlmuth, Residual based a posteriori error estimators for eddy current computation. M 2 AN Math. Modeling and Numer. Anal. 34, , 2. [1] R. Beck, R. Hiptmair, and B. Wohlmuth, Hierarchical error estimator for eddy current computation. In: Proc. 2nd European Conf. on Advanced Numer. Meth. ENUMATH99, Jyväskylä, inland, July 26-3, 1999 Neittaanmäki, P. et al.; eds., pp , World Scientific, Singapore, 2. [11] R. Becker, P. Hansbo, and M.G. Larson, Energy norm a posteriori error estimation for discontinuous Galerkin methods. Comput. Methods Appl. Mech. Engrg. 192, , 23. [12] A. Bonito and R. Nochetto, Quasi-optimal convergence rate of an adaptive Discontinuous Galerkin method. Preprint. Department of Mathematics, University of Maryland, 28. [13] J.H. Bramble and J. Xu, A local post-processing technique for improving the accuracy in mixed finite element approximations. SIAM J. Numer. Anal. 26, , [14] J. Brandts, Superconvergence and a posteriori error estimation for triangular mixed finite element methods. Numer. Math. 68, , [15]. Brezzi, J. Douglas, Jr., and L.D. Marini, Two families of mixed finite elements for second order elliptic problems. Numer. Math. 47, , [16] A. Buffa, M. Costabel, and D. Sheen, On traces for Hcurl, Ω in Lipschitz domains, J. Math. Anal. Appl. 276, , 22. [17] C. Carstensen, A unifying theory of a posteriori finite element error control. Numer. Math. 1, , 25. [18] C. Carstensen, T. Gudi, and M. Jensen, A unifying theory of a posteriori error control for discontinuous Galerkin EM. Numer. Math. 112, , 29. [19] C. Carstensen and R.H.W. Hoppe, Convergence analysis of an adaptive edge finite element method for the 2d eddy current equations. J. Numer. Math. 13, 19 32, 25. [2] C. Carstensen and R.H.W. Hoppe, Unified framework for an a posteriori error analysis of nonstandard finite element approximations of Hcurl-elliptic problems. J. Numer. Math. 17, 27 44, 29. [21] C. Carstensen and J. Hu, A unifying theory of a posteriori error control for nonconforming finite element methods. Numer. Math. 17, , 27. [22] C. Carstensen, J. Hu, and A. Orlando, ramework for the a posteriori error analysis of nonconforming finite elements. SIAM J. Numer. Anal. 45, 68 82, 27. [23] P. Castillo, B. Cockburn, I. Perugia, and D. Schötzau, An a priori error estimate of the local discontinuous Galerkin method for elliptic problems. SIAM J. Numer. Anal. 38, , 2. [24] B. Cockburn, Discontinuous Galerkin methods. Z. Angew. Math. Mech. 83, , 23. 2
21 [25] Cockburn, B., and Gopalakrishnan, J.; A characterization of hybridized mixed methods for second order elliptic problems. SIAM J. Numer. Anal. 42, , 24. [26] Cockburn, B., and Gopalakrishnan, J.; Error analysis of variable degree mixed methods for elliptic problems via hybridization. Math. Comp. 74, , 25. [27] Cockburn, B., and Gopalakrishnan, J.; New hybridization techniques. GAMM-Mitteilungen 2, [28] Cockburn, B., Gopalakrishnan, J., and Lazarov, R.; Unified hybridization of discontinuous Galerkin, Mixed and continuous Galerkin methods for second order elliptic problems. SIAM J. Numer. Anal. 47, , 29. [29] Dörfler, W.; A convergent adaptive algorithm for Poisson s equation. SIAM J. Numer. Anal. 33, , [3] K. Eriksson, D. Estep, P. Hansbo, and C. Johnson, Computational Differential Equations. Cambridge University Press, Cambridge, [31] B.M. raejis de Veubeke, Displacement and equilibrium methods in the finite element method. In: Stress Analysis O. Zienkiewicz and G. Hollister; eds., pp , Wiley, New York, [32] V. Girault and P.A. Raviart, inite Element Approximatiuon of the Navier-Stokes Equations. Lecture Notes in Mathematics 749, Springer, Berlin-Heidelberg-New York, [33] J.S. Hesthaven and T. Warburton, Nodal Discontinuous Galerkin Methods. Springer, Berlin- Heidelberg-New York, 28. [34] R.H.W. Hoppe, G. Kanschat, and T. Warburton, Convergence analysis of an adaptive interior penalty discontinuous Galerkin method. SIAM J. Numer. Anal., 47, , 29. [35] R.H.W. Hoppe and J. Schöberl, Convergence of adaptive edge element methods for the 3D eddy currents equations. J. Comp. Math. 27, , 29. [36] P. Houston, I. Perugia, and D. Schötzau, Mixed discontinuous Galerkin approximation of the Maxwell operator. SIAM J. Numer. Anal. 42, , 24. [37] P. Houston, I. Perugia, and D. Schötzau, A posteriori error estimation for discontinuous Galerkin discretizations of Hcurl-elliptic partial differential equations. IMA Journal of Numerical Analysis 27, , 27. [38] P. Houston, D. Schötzau, and T.P. Wihler, Energy norm a posteriori error estimation of hpadaptive discontinuous Galerkin methods for elliptic problems. Math. Models Methods Appl. Sci. 17, 33 62, 27. [39] G. Kanschat and R. Rannacher, Local error analysis of the interior penalty discontinuous Galerkin method for second order problems. J. Numer. Math. 1, , 22. [4] O. Karakashian and. Pascal, A posteriori error estimates for a discontinuous Galerkin approximation of second-order elliptic problems. SIAM J. Numer. Anal. 41, , 23. [41] O. Karakashian and. Pascal, Convergence of adaptive Doiscontinuous Galerkin approximations of second-order elliptic problems. SIAM J. Numer. Anal. 45, , 27. [42] P. Monk, inite Element Methods for Maxwell s equations, Clarendon Press, Oxford, 23. [43] J.C. Nédélec, Mixed finite elements in R 3, Numer. Math. 35, , 198. [44] P. Neittaanmäki and S. Repin, Reliable methods for mathematical modelling. Error control and a posteriori estimates. Elsevier, New York, 24. [45] S. Nicaise and E. Creusé, Isotropic and anisotropic a posteriori error estimation of the mixed finite element method for second order operators in divergence form. ETNA 23, 38 62, 26. [46] I. Perugia, D. Schötzau, and P. Monk, Stabilized interior penalty methods for the time-harmonic Maxwell equations. Comp. Meth. Appl. Mech. Engrg. 191, , 22. [47] B. Rivière and M.. Wheeler, A posteriori error estimates and mesh adaptation strategy for discontinuous Galerkin methods applied to diffusion problems. Computers & Mathematics with Applications 46, , 23. [48] J. Schöberl, A posteriori error estimates for Maxwell equations, Math. Comp. 77, , 28. [49] R. Verfürth, A Review of A Posteriori Estimation and Adaptive Mesh-Refinement Techniques. Wiley-Teubner, New York, Stuttgart, [5] B. Wohlmuth and R.H.W. Hoppe, A comparison of a posteriori error estimators for mixed finite element discretizations. Math. Comp. 82, , [51] X. Xu and R.H.W. Hoppe, On the convergence of mortar edge element methods in R 3. SIAM J. Numer. Anal. 43, ,
Chapter 6 A posteriori error estimates for finite element approximations 6.1 Introduction
Chapter 6 A posteriori error estimates for finite element approximations 6.1 Introduction The a posteriori error estimation of finite element approximations of elliptic boundary value problems has reached
More informationLocal discontinuous Galerkin methods for elliptic problems
COMMUNICATIONS IN NUMERICAL METHODS IN ENGINEERING Commun. Numer. Meth. Engng 2002; 18:69 75 [Version: 2000/03/22 v1.0] Local discontinuous Galerkin methods for elliptic problems P. Castillo 1 B. Cockburn
More informationAN EQUILIBRATED A POSTERIORI ERROR ESTIMATOR FOR THE INTERIOR PENALTY DISCONTINUOUS GALERKIN METHOD
AN EQUILIBRATED A POSTERIORI ERROR ESTIMATOR FOR THE INTERIOR PENALTY DISCONTINUOUS GALERIN METHOD D. BRAESS, T. FRAUNHOLZ, AND R. H. W. HOPPE Abstract. Interior Penalty Discontinuous Galerkin (IPDG) methods
More informationarxiv: v2 [math.na] 23 Apr 2016
Improved ZZ A Posteriori Error Estimators for Diffusion Problems: Conforming Linear Elements arxiv:508.009v2 [math.na] 23 Apr 206 Zhiqiang Cai Cuiyu He Shun Zhang May 2, 208 Abstract. In [8], we introduced
More informationENERGY NORM A POSTERIORI ERROR ESTIMATES FOR MIXED FINITE ELEMENT METHODS
ENERGY NORM A POSTERIORI ERROR ESTIMATES FOR MIXED FINITE ELEMENT METHODS CARLO LOVADINA AND ROLF STENBERG Abstract The paper deals with the a-posteriori error analysis of mixed finite element methods
More informationEnergy norm a-posteriori error estimation for divergence-free discontinuous Galerkin approximations of the Navier-Stokes equations
INTRNATIONAL JOURNAL FOR NUMRICAL MTHODS IN FLUIDS Int. J. Numer. Meth. Fluids 19007; 1:1 [Version: 00/09/18 v1.01] nergy norm a-posteriori error estimation for divergence-free discontinuous Galerkin approximations
More informationInstitut für Mathematik
U n i v e r s i t ä t A u g s b u r g Institut für Mathematik Dietrich Braess, Carsten Carstensen, and Ronald H.W. Hoppe Convergence Analysis of a Conforming Adaptive Finite Element Method for an Obstacle
More informationA note on discontinuous Galerkin divergence-free solutions of the Navier-Stokes equations
A note on discontinuous Galerkin divergence-free solutions of the Navier-Stokes equations Bernardo Cockburn Guido anschat Dominik Schötzau June 1, 2007 Journal of Scientific Computing, Vol. 31, 2007, pp.
More informationAn a posteriori error indicator for discontinuous Galerkin discretizations of H(curl) elliptic partial differential equations
IMA Journal of Numerical Analysis 005) Page of 7 doi: 0.093/imanum/ An a posteriori error indicator for discontinuous Galerkin discretizations of Hcurl) elliptic partial differential equations PAUL HOUSTON
More informationLecture Note III: Least-Squares Method
Lecture Note III: Least-Squares Method Zhiqiang Cai October 4, 004 In this chapter, we shall present least-squares methods for second-order scalar partial differential equations, elastic equations of solids,
More informationA posteriori error estimates for a Maxwell type problem
Russ. J. Numer. Anal. Math. Modelling, Vol. 24, No. 5, pp. 395 408 (2009) DOI 0.55/ RJNAMM.2009.025 c de Gruyter 2009 A posteriori error estimates for a Maxwell type problem I. ANJAM, O. MALI, A. MUZALEVSKY,
More informationarxiv: v1 [math.na] 29 Feb 2016
EFFECTIVE IMPLEMENTATION OF THE WEAK GALERKIN FINITE ELEMENT METHODS FOR THE BIHARMONIC EQUATION LIN MU, JUNPING WANG, AND XIU YE Abstract. arxiv:1602.08817v1 [math.na] 29 Feb 2016 The weak Galerkin (WG)
More informationA Multigrid Method for Two Dimensional Maxwell Interface Problems
A Multigrid Method for Two Dimensional Maxwell Interface Problems Susanne C. Brenner Department of Mathematics and Center for Computation & Technology Louisiana State University USA JSA 2013 Outline A
More informationAn a posteriori error estimate and a Comparison Theorem for the nonconforming P 1 element
Calcolo manuscript No. (will be inserted by the editor) An a posteriori error estimate and a Comparison Theorem for the nonconforming P 1 element Dietrich Braess Faculty of Mathematics, Ruhr-University
More informationUnified A Posteriori Error Control for all Nonstandard Finite Elements 1
Unified A Posteriori Error Control for all Nonstandard Finite Elements 1 Martin Eigel C. Carstensen, C. Löbhard, R.H.W. Hoppe Humboldt-Universität zu Berlin 19.05.2010 1 we know of Guidelines for Applicants
More informationInstitut für Mathematik
U n i v e r s i t ä t A u g s b u r g Institut für Mathematik Ronald H.W. Hoppe, Irwin Yousept Adaptive Edge Element Approximation of H(curl-Elliptic Optimal Control Problems with Control Constraints Preprint
More informationA posteriori error estimator based on gradient recovery by averaging for discontinuous Galerkin methods
A posteriori error estimator based on gradient recovery by averaging for discontinuous Galerkin methods Emmanuel Creusé, Serge Nicaise October 7, 29 Abstract We consider some (anisotropic and piecewise
More informationMaximum-norm a posteriori estimates for discontinuous Galerkin methods
Maximum-norm a posteriori estimates for discontinuous Galerkin methods Emmanuil Georgoulis Department of Mathematics, University of Leicester, UK Based on joint work with Alan Demlow (Kentucky, USA) DG
More informationA posteriori error estimates for Maxwell Equations
www.oeaw.ac.at A posteriori error estimates for Maxwell Equations J. Schöberl RICAM-Report 2005-10 www.ricam.oeaw.ac.at A POSTERIORI ERROR ESTIMATES FOR MAXWELL EQUATIONS JOACHIM SCHÖBERL Abstract. Maxwell
More informationDiscontinuous Galerkin Methods: Theory, Computation and Applications
Discontinuous Galerkin Methods: Theory, Computation and Applications Paola. Antonietti MOX, Dipartimento di Matematica Politecnico di Milano.MO. X MODELLISTICA E CALCOLO SCIENTIICO. MODELING AND SCIENTIIC
More informationPARTITION OF UNITY FOR THE STOKES PROBLEM ON NONMATCHING GRIDS
PARTITION OF UNITY FOR THE STOES PROBLEM ON NONMATCHING GRIDS CONSTANTIN BACUTA AND JINCHAO XU Abstract. We consider the Stokes Problem on a plane polygonal domain Ω R 2. We propose a finite element method
More informationETNA Kent State University
Electronic Transactions on Numerical Analysis. Volume 37, pp. 166-172, 2010. Copyright 2010,. ISSN 1068-9613. ETNA A GRADIENT RECOVERY OPERATOR BASED ON AN OBLIQUE PROJECTION BISHNU P. LAMICHHANE Abstract.
More informationYongdeok Kim and Seki Kim
J. Korean Math. Soc. 39 (00), No. 3, pp. 363 376 STABLE LOW ORDER NONCONFORMING QUADRILATERAL FINITE ELEMENTS FOR THE STOKES PROBLEM Yongdeok Kim and Seki Kim Abstract. Stability result is obtained for
More informationMIXED FINITE ELEMENT METHODS FOR PROBLEMS WITH ROBIN BOUNDARY CONDITIONS
MIXED FINITE ELEMENT METHODS FOR PROBLEMS WITH ROBIN BOUNDARY CONDITIONS JUHO KÖNNÖ, DOMINIK SCHÖTZAU, AND ROLF STENBERG Abstract. We derive new a-priori and a-posteriori error estimates for mixed nite
More informationA posteriori error estimates applied to flow in a channel with corners
Mathematics and Computers in Simulation 61 (2003) 375 383 A posteriori error estimates applied to flow in a channel with corners Pavel Burda a,, Jaroslav Novotný b, Bedřich Sousedík a a Department of Mathematics,
More informationHybridized Discontinuous Galerkin Methods
Hybridized Discontinuous Galerkin Methods Theory and Christian Waluga Joint work with Herbert Egger (Uni Graz) 1st DUNE User Meeting, Stuttgart Christian Waluga (AICES) HDG Methods October 6-8, 2010 1
More informationSTABILIZED DISCONTINUOUS FINITE ELEMENT APPROXIMATIONS FOR STOKES EQUATIONS
STABILIZED DISCONTINUOUS FINITE ELEMENT APPROXIMATIONS FOR STOKES EQUATIONS RAYTCHO LAZAROV AND XIU YE Abstract. In this paper, we derive two stabilized discontinuous finite element formulations, symmetric
More informationENERGY NORM A POSTERIORI ERROR ESTIMATES FOR MIXED FINITE ELEMENT METHODS
MATHEMATICS OF COMPUTATION Volume 75, Number 256, October 2006, Pages 1659 1674 S 0025-57180601872-2 Article electronically published on June 26, 2006 ENERGY NORM A POSTERIORI ERROR ESTIMATES FOR MIXED
More informationA Mixed Nonconforming Finite Element for Linear Elasticity
A Mixed Nonconforming Finite Element for Linear Elasticity Zhiqiang Cai, 1 Xiu Ye 2 1 Department of Mathematics, Purdue University, West Lafayette, Indiana 47907-1395 2 Department of Mathematics and Statistics,
More informationMultigrid Methods for Maxwell s Equations
Multigrid Methods for Maxwell s Equations Jintao Cui Institute for Mathematics and Its Applications University of Minnesota Outline Nonconforming Finite Element Methods for a Two Dimensional Curl-Curl
More informationA Posteriori Estimates for Cost Functionals of Optimal Control Problems
A Posteriori Estimates for Cost Functionals of Optimal Control Problems Alexandra Gaevskaya, Ronald H.W. Hoppe,2 and Sergey Repin 3 Institute of Mathematics, Universität Augsburg, D-8659 Augsburg, Germany
More informationELLIPTIC RECONSTRUCTION AND A POSTERIORI ERROR ESTIMATES FOR PARABOLIC PROBLEMS
ELLIPTIC RECONSTRUCTION AND A POSTERIORI ERROR ESTIMATES FOR PARABOLIC PROBLEMS CHARALAMBOS MAKRIDAKIS AND RICARDO H. NOCHETTO Abstract. It is known that the energy technique for a posteriori error analysis
More informationb i (x) u + c(x)u = f in Ω,
SIAM J. NUMER. ANAL. Vol. 39, No. 6, pp. 1938 1953 c 2002 Society for Industrial and Applied Mathematics SUBOPTIMAL AND OPTIMAL CONVERGENCE IN MIXED FINITE ELEMENT METHODS ALAN DEMLOW Abstract. An elliptic
More informationHybridized DG methods
Hybridized DG methods University of Florida (Banff International Research Station, November 2007.) Collaborators: Bernardo Cockburn University of Minnesota Raytcho Lazarov Texas A&M University Thanks:
More informationAdaptive methods for control problems with finite-dimensional control space
Adaptive methods for control problems with finite-dimensional control space Saheed Akindeinde and Daniel Wachsmuth Johann Radon Institute for Computational and Applied Mathematics (RICAM) Austrian Academy
More informationarxiv: v3 [math.na] 8 Sep 2015
A Recovery-Based A Posteriori Error Estimator for H(curl) Interface Problems arxiv:504.00898v3 [math.na] 8 Sep 205 Zhiqiang Cai Shuhao Cao Abstract This paper introduces a new recovery-based a posteriori
More informationBasic Concepts of Adaptive Finite Element Methods for Elliptic Boundary Value Problems
Basic Concepts of Adaptive Finite lement Methods for lliptic Boundary Value Problems Ronald H.W. Hoppe 1,2 1 Department of Mathematics, University of Houston 2 Institute of Mathematics, University of Augsburg
More informationA NONCONFORMING PENALTY METHOD FOR A TWO DIMENSIONAL CURL-CURL PROBLEM
A NONCONFORMING PENALTY METHOD FOR A TWO DIMENSIONAL CURL-CURL PROBLEM SUSANNE C. BRENNER, FENGYAN LI, AND LI-YENG SUNG Abstract. A nonconforming penalty method for a two-dimensional curl-curl problem
More informationNon-Conforming Finite Element Methods for Nonmatching Grids in Three Dimensions
Non-Conforming Finite Element Methods for Nonmatching Grids in Three Dimensions Wayne McGee and Padmanabhan Seshaiyer Texas Tech University, Mathematics and Statistics (padhu@math.ttu.edu) Summary. In
More informationBasic Principles of Weak Galerkin Finite Element Methods for PDEs
Basic Principles of Weak Galerkin Finite Element Methods for PDEs Junping Wang Computational Mathematics Division of Mathematical Sciences National Science Foundation Arlington, VA 22230 Polytopal Element
More informationA Posteriori Error Estimation Techniques for Finite Element Methods. Zhiqiang Cai Purdue University
A Posteriori Error Estimation Techniques for Finite Element Methods Zhiqiang Cai Purdue University Department of Mathematics, Purdue University Slide 1, March 16, 2017 Books Ainsworth & Oden, A posteriori
More informationA UNIFYING THEORY OF A POSTERIORI FINITE ELEMENT ERROR CONTROL
A UNIFYING THEORY OF A POSTERIORI FINITE ELEMENT ERROR CONTROL C. CARSTENSEN Abstract. Residual-based a posteriori error estimates are derived within a unified setting for lowest-order conforming, nonconforming,
More informationAn interpolation operator for H 1 functions on general quadrilateral and hexahedral meshes with hanging nodes
An interpolation operator for H 1 functions on general quadrilateral and hexahedral meshes with hanging nodes Vincent Heuveline Friedhelm Schieweck Abstract We propose a Scott-Zhang type interpolation
More informationICES REPORT Analysis of the DPG Method for the Poisson Equation
ICES REPORT 10-37 September 2010 Analysis of the DPG Method for the Poisson Equation by L. Demkowicz and J. Gopalakrishnan The Institute for Computational Engineering and Sciences The University of Texas
More informationOn an Approximation Result for Piecewise Polynomial Functions. O. Karakashian
BULLETIN OF THE GREE MATHEMATICAL SOCIETY Volume 57, 010 (1 7) On an Approximation Result for Piecewise Polynomial Functions O. arakashian Abstract We provide a new approach for proving approximation results
More informationSECOND ORDER TIME DISCONTINUOUS GALERKIN METHOD FOR NONLINEAR CONVECTION-DIFFUSION PROBLEMS
Proceedings of ALGORITMY 2009 pp. 1 10 SECOND ORDER TIME DISCONTINUOUS GALERKIN METHOD FOR NONLINEAR CONVECTION-DIFFUSION PROBLEMS MILOSLAV VLASÁK Abstract. We deal with a numerical solution of a scalar
More informationAnalysis of Hybrid Discontinuous Galerkin Methods for Incompressible Flow Problems
Analysis of Hybrid Discontinuous Galerkin Methods for Incompressible Flow Problems Christian Waluga 1 advised by Prof. Herbert Egger 2 Prof. Wolfgang Dahmen 3 1 Aachen Institute for Advanced Study in Computational
More informationUNIFIED A POSTERIORI ERROR ESTIMATOR FOR FINITE ELEMENT METHODS FOR THE STOKES EQUATIONS
INTERNATIONAL JOURNAL OF NUMERICAL ANALYSIS AND MODELING Volume 10, Number 3, Pages 551 570 c 013 Institute for Scientific Computing and Information UNIFIED A POSTERIORI ERROR ESTIMATOR FOR FINITE ELEMENT
More informationMULTIGRID PRECONDITIONING IN H(div) ON NON-CONVEX POLYGONS* Dedicated to Professor Jim Douglas, Jr. on the occasion of his seventieth birthday.
MULTIGRID PRECONDITIONING IN H(div) ON NON-CONVEX POLYGONS* DOUGLAS N ARNOLD, RICHARD S FALK, and RAGNAR WINTHER Dedicated to Professor Jim Douglas, Jr on the occasion of his seventieth birthday Abstract
More informationAn Equal-order DG Method for the Incompressible Navier-Stokes Equations
An Equal-order DG Method for the Incompressible Navier-Stokes Equations Bernardo Cockburn Guido anschat Dominik Schötzau Journal of Scientific Computing, vol. 40, pp. 188 10, 009 Abstract We introduce
More informationDivergence-conforming multigrid methods for incompressible flow problems
Divergence-conforming multigrid methods for incompressible flow problems Guido Kanschat IWR, Universität Heidelberg Prague-Heidelberg-Workshop April 28th, 2015 G. Kanschat (IWR, Uni HD) Hdiv-DG Práha,
More informationETNA Kent State University
Electronic Transactions on Numerical Analysis. Volume 11, pp. 1-24, 2000. Copyright 2000,. ISSN 1068-9613. ETNA NEUMANN NEUMANN METHODS FOR VECTOR FIELD PROBLEMS ANDREA TOSELLI Abstract. In this paper,
More informationChapter 1 Mathematical Foundations
Computational Electromagnetics; Chapter 1 1 Chapter 1 Mathematical Foundations 1.1 Maxwell s Equations Electromagnetic phenomena can be described by the electric field E, the electric induction D, the
More informationelement stiffness matrix, 21
Bibliography [1] R. Adams, Sobolev Spaces, Academic Press, 1975. [2] C. Amrouche, C. Bernardi, M. Dauge, and V. Girault, Vector potentials in three-diemnsional nonsmooth domains, Math. Meth. Appl. Sci.,
More informationA mixed finite element approximation of the Stokes equations with the boundary condition of type (D+N)
wwwijmercom Vol2, Issue1, Jan-Feb 2012 pp-464-472 ISSN: 2249-6645 A mixed finite element approximation of the Stokes equations with the boundary condition of type (D+N) Jaouad El-Mekkaoui 1, Abdeslam Elakkad
More informationA local-structure-preserving local discontinuous Galerkin method for the Laplace equation
A local-structure-preserving local discontinuous Galerkin method for the Laplace equation Fengyan Li 1 and Chi-Wang Shu 2 Abstract In this paper, we present a local-structure-preserving local discontinuous
More informationA NOTE ON THE LADYŽENSKAJA-BABUŠKA-BREZZI CONDITION
A NOTE ON THE LADYŽENSKAJA-BABUŠKA-BREZZI CONDITION JOHNNY GUZMÁN, ABNER J. SALGADO, AND FRANCISCO-JAVIER SAYAS Abstract. The analysis of finite-element-like Galerkin discretization techniques for the
More informationarxiv: v1 [math.na] 19 Dec 2017
Arnold-Winther Mixed Finite Elements for Stokes Eigenvalue Problems Joscha Gedicke Arbaz Khan arxiv:72.0686v [math.na] 9 Dec 207 Abstract This paper is devoted to study the Arnold-Winther mixed finite
More informationAMS subject classifications. Primary, 65N15, 65N30, 76D07; Secondary, 35B45, 35J50
A SIMPLE FINITE ELEMENT METHOD FOR THE STOKES EQUATIONS LIN MU AND XIU YE Abstract. The goal of this paper is to introduce a simple finite element method to solve the Stokes equations. This method is in
More informationA posteriori error estimates for non conforming approximation of eigenvalue problems
A posteriori error estimates for non conforming approximation of eigenvalue problems E. Dari a, R. G. Durán b and C. Padra c, a Centro Atómico Bariloche, Comisión Nacional de Energía Atómica and CONICE,
More informationA priori error analysis of the BEM with graded meshes for the electric eld integral equation on polyhedral surfaces
A priori error analysis of the BEM with graded meshes for the electric eld integral equation on polyhedral surfaces A. Bespalov S. Nicaise Abstract The Galerkin boundary element discretisations of the
More informationA Hybrid Discontinuous Galerkin Method 2 for Darcy-Stokes Problems 3 UNCORRECTED PROOF
1 A Hybrid Discontinuous Galerkin Method 2 for Darcy-Stokes Problems 3 Herbert Egger 1 and Christian Waluga 2 4 1 Center of Mathematics, Technische Universität München, Boltzmannstraße 3, 85748 5 Garching
More information1. Introduction. The Stokes problem seeks unknown functions u and p satisfying
A DISCRETE DIVERGENCE FREE WEAK GALERKIN FINITE ELEMENT METHOD FOR THE STOKES EQUATIONS LIN MU, JUNPING WANG, AND XIU YE Abstract. A discrete divergence free weak Galerkin finite element method is developed
More informationAn hp-adaptive Mixed Discontinuous Galerkin FEM for Nearly Incompressible Linear Elasticity
An hp-adaptive Mixed Discontinuous Galerkin FEM for Nearly Incompressible Linear Elasticity Paul Houston 1 Department of Mathematics, University of Leicester, Leicester LE1 7RH, UK (email: Paul.Houston@mcs.le.ac.uk)
More informationBUBBLE STABILIZED DISCONTINUOUS GALERKIN METHOD FOR STOKES PROBLEM
BUBBLE STABILIZED DISCONTINUOUS GALERKIN METHOD FOR STOKES PROBLEM ERIK BURMAN AND BENJAMIN STAMM Abstract. We propose a low order discontinuous Galerkin method for incompressible flows. Stability of the
More informationA POSTERIORI ERROR ESTIMATES FOR MAXWELL EQUATIONS
A POSTERIORI ERROR ESTIMATES FOR MAXWELL EQUATIONS JOACHIM SCHÖBERL Abstract. Maxwell equations are posed as variational boundary value problems in the function space H(curl) and are discretized by Nédélec
More informationDiscontinuous Galerkin Methods
Discontinuous Galerkin Methods Joachim Schöberl May 20, 206 Discontinuous Galerkin (DG) methods approximate the solution with piecewise functions (polynomials), which are discontinuous across element interfaces.
More information1. Introduction. We consider the model problem: seeking an unknown function u satisfying
A DISCONTINUOUS LEAST-SQUARES FINITE ELEMENT METHOD FOR SECOND ORDER ELLIPTIC EQUATIONS XIU YE AND SHANGYOU ZHANG Abstract In tis paper, a discontinuous least-squares (DLS) finite element metod is introduced
More informationOn Dual-Weighted Residual Error Estimates for p-dependent Discretizations
On Dual-Weighted Residual Error Estimates for p-dependent Discretizations Aerospace Computational Design Laboratory Report TR-11-1 Masayuki Yano and David L. Darmofal September 21, 2011 Abstract This report
More informationPREPRINT 2010:25. Fictitious domain finite element methods using cut elements: II. A stabilized Nitsche method ERIK BURMAN PETER HANSBO
PREPRINT 2010:25 Fictitious domain finite element methods using cut elements: II. A stabilized Nitsche method ERIK BURMAN PETER HANSBO Department of Mathematical Sciences Division of Mathematics CHALMERS
More informationA LAGRANGE MULTIPLIER METHOD FOR ELLIPTIC INTERFACE PROBLEMS USING NON-MATCHING MESHES
A LAGRANGE MULTIPLIER METHOD FOR ELLIPTIC INTERFACE PROBLEMS USING NON-MATCHING MESHES P. HANSBO Department of Applied Mechanics, Chalmers University of Technology, S-4 96 Göteborg, Sweden E-mail: hansbo@solid.chalmers.se
More informationA PROJECTION-BASED ERROR ANALYSIS OF HDG METHODS BERNARDO COCKBURN, JAYADEEP GOPALAKRISHNAN, AND FRANCISCO-JAVIER SAYAS
A PROJECTION-BASED ERROR ANALYSIS OF HDG METHODS BERNARDO COCBURN, JAYADEEP GOPALARISHNAN, AND FRANCISCO-JAVIER SAYAS Abstract. We introduce a new technique for the error analysis of hybridizable discontinuous
More informationAn A Posteriori Error Estimate for Discontinuous Galerkin Methods
An A Posteriori Error Estimate for Discontinuous Galerkin Methods Mats G Larson mgl@math.chalmers.se Chalmers Finite Element Center Mats G Larson Chalmers Finite Element Center p.1 Outline We present an
More informationMultigrid Methods for Saddle Point Problems
Multigrid Methods for Saddle Point Problems Susanne C. Brenner Department of Mathematics and Center for Computation & Technology Louisiana State University Advances in Mathematics of Finite Elements (In
More informationDifferent Approaches to a Posteriori Error Analysis of the Discontinuous Galerkin Method
WDS'10 Proceedings of Contributed Papers, Part I, 151 156, 2010. ISBN 978-80-7378-139-2 MATFYZPRESS Different Approaces to a Posteriori Error Analysis of te Discontinuous Galerkin Metod I. Šebestová Carles
More informationA posteriori error estimates in FEEC for the de Rham complex
A posteriori error estimates in FEEC for the de Rham complex Alan Demlow Texas A&M University joint work with Anil Hirani University of Illinois Urbana-Champaign Partially supported by NSF DMS-1016094
More informationRecovery-Based A Posteriori Error Estimation
Recovery-Based A Posteriori Error Estimation Zhiqiang Cai Purdue University Department of Mathematics, Purdue University Slide 1, March 2, 2011 Outline Introduction Diffusion Problems Higher Order Elements
More informationASM-BDDC Preconditioners with variable polynomial degree for CG- and DG-SEM
ASM-BDDC Preconditioners with variable polynomial degree for CG- and DG-SEM C. Canuto 1, L. F. Pavarino 2, and A. B. Pieri 3 1 Introduction Discontinuous Galerkin (DG) methods for partial differential
More informationEnhancing eigenvalue approximation by gradient recovery on adaptive meshes
IMA Journal of Numerical Analysis Advance Access published October 29, 2008 IMA Journal of Numerical Analysis Page 1 of 15 doi:10.1093/imanum/drn050 Enhancing eigenvalue approximation by gradient recovery
More informationAn a posteriori error estimator for the weak Galerkin least-squares finite-element method
An a posteriori error estimator for the weak Galerkin least-squares finite-element method James H. Adler a, Xiaozhe Hu a, Lin Mu b, Xiu Ye c a Department of Mathematics, Tufts University, Medford, MA 02155
More informationPhD dissertation defense
Isogeometric mortar methods with applications in contact mechanics PhD dissertation defense Brivadis Ericka Supervisor: Annalisa Buffa Doctor of Philosophy in Computational Mechanics and Advanced Materials,
More informationNumerical approximation of output functionals for Maxwell equations
Numerical approximation of output functionals for Maxwell equations Ferenc Izsák ELTE, Budapest University of Twente, Enschede 11 September 2004 MAXWELL EQUATIONS Assumption: electric field ( electromagnetic
More informationNumerische Mathematik
Numer. Math. (2003) 94: 195 202 Digital Object Identifier (DOI) 10.1007/s002110100308 Numerische Mathematik Some observations on Babuška and Brezzi theories Jinchao Xu, Ludmil Zikatanov Department of Mathematics,
More informationA primer on Numerical methods for elasticity
A primer on Numerical methods for elasticity Douglas N. Arnold, University of Minnesota Complex materials: Mathematical models and numerical methods Oslo, June 10 12, 2015 One has to resort to the indignity
More informationA Finite Element Method Using Singular Functions for Poisson Equations: Mixed Boundary Conditions
A Finite Element Method Using Singular Functions for Poisson Equations: Mixed Boundary Conditions Zhiqiang Cai Seokchan Kim Sangdong Kim Sooryun Kong Abstract In [7], we proposed a new finite element method
More informationIntroduction to finite element exterior calculus
Introduction to finite element exterior calculus Ragnar Winther CMA, University of Oslo Norway Why finite element exterior calculus? Recall the de Rham complex on the form: R H 1 (Ω) grad H(curl, Ω) curl
More informationA posteriori error estimation of approximate boundary fluxes
COMMUNICATIONS IN NUMERICAL METHODS IN ENGINEERING Commun. Numer. Meth. Engng 2008; 24:421 434 Published online 24 May 2007 in Wiley InterScience (www.interscience.wiley.com)..1014 A posteriori error estimation
More informationScientific Computing WS 2018/2019. Lecture 15. Jürgen Fuhrmann Lecture 15 Slide 1
Scientific Computing WS 2018/2019 Lecture 15 Jürgen Fuhrmann juergen.fuhrmann@wias-berlin.de Lecture 15 Slide 1 Lecture 15 Slide 2 Problems with strong formulation Writing the PDE with divergence and gradient
More informationFind (u,p;λ), with u 0 and λ R, such that u + p = λu in Ω, (2.1) div u = 0 in Ω, u = 0 on Γ.
A POSTERIORI ESTIMATES FOR THE STOKES EIGENVALUE PROBLEM CARLO LOVADINA, MIKKO LYLY, AND ROLF STENBERG Abstract. We consider the Stokes eigenvalue problem. For the eigenvalues we derive both upper and
More informationIMPROVED LEAST-SQUARES ERROR ESTIMATES FOR SCALAR HYPERBOLIC PROBLEMS, 1
Computational Methods in Applied Mathematics Vol. 1, No. 1(2001) 1 8 c Institute of Mathematics IMPROVED LEAST-SQUARES ERROR ESTIMATES FOR SCALAR HYPERBOLIC PROBLEMS, 1 P.B. BOCHEV E-mail: bochev@uta.edu
More informationAdaptive Finite Element Methods Lecture 1: A Posteriori Error Estimation
Adaptive Finite Element Methods Lecture 1: A Posteriori Error Estimation Department of Mathematics and Institute for Physical Science and Technology University of Maryland, USA www.math.umd.edu/ rhn 7th
More informationNedelec elements for computational electromagnetics
Nedelec elements for computational electromagnetics Per Jacobsson, June 5, 2007 Maxwell s equations E = jωµh () H = jωεe + J (2) (εe) = ρ (3) (µh) = 0 (4) J = jωρ (5) Only three of the equations are needed,
More informationSchur Complements on Hilbert Spaces and Saddle Point Systems
Schur Complements on Hilbert Spaces and Saddle Point Systems Constantin Bacuta Mathematical Sciences, University of Delaware, 5 Ewing Hall 976 Abstract For any continuous bilinear form defined on a pair
More informationKey words. Incompressible magnetohydrodynamics, mixed finite element methods, discontinuous Galerkin methods
A MIXED DG METHOD FOR LINEARIZED INCOMPRESSIBLE MAGNETOHYDRODYNAMICS PAUL HOUSTON, DOMINIK SCHÖTZAU, AND XIAOXI WEI Journal of Scientific Computing, vol. 40, pp. 8 34, 009 Abstract. We introduce and analyze
More informationDISCRETE EXTENSION OPERATORS FOR MIXED FINITE ELEMENT SPACES ON LOCALLY REFINED MESHES
DISCRETE EXTENSION OPERATORS FOR MIXED FINITE ELEMENT SPACES ON LOCALLY REFINED MESHES MAR AINSWORTH, JOHNNY GUZMÁN, AND FRANCISCO JAVIER SAYAS Abstract. The existence of uniformly bounded discrete extension
More informationEnergy Norm A Posteriori Error Estimation for Mixed Discontinuous Galerkin Approximations of the Stokes Problem
idgenössische Technische Hochschule Zürich cole polytechnique fédérale de Zurich Politecnico federale di Zurigo Swiss Federal Institute of Technology Zurich nergy Norm A Posteriori rror stimation for Mixed
More informationGoal. Robust A Posteriori Error Estimates for Stabilized Finite Element Discretizations of Non-Stationary Convection-Diffusion Problems.
Robust A Posteriori Error Estimates for Stabilized Finite Element s of Non-Stationary Convection-Diffusion Problems L. Tobiska and R. Verfürth Universität Magdeburg Ruhr-Universität Bochum www.ruhr-uni-bochum.de/num
More informationNumerische Mathematik
Numer. Math. (2012) 122:61 99 DOI 10.1007/s00211-012-0456-x Numerische Mathematik C 0 elements for generalized indefinite Maxwell equations Huoyuan Duan Ping Lin Roger C. E. Tan Received: 31 July 2010
More informationEXISTENCE AND REGULARITY OF SOLUTIONS FOR STOKES SYSTEMS WITH NON-SMOOTH BOUNDARY DATA IN A POLYHEDRON
Electronic Journal of Differential Equations, Vol. 2017 (2017), No. 147, pp. 1 10. ISSN: 1072-6691. URL: http://ejde.math.txstate.edu or http://ejde.math.unt.edu EXISTENCE AND REGULARITY OF SOLUTIONS FOR
More informationA POSTERIORI ERROR ESTIMATES OF TRIANGULAR MIXED FINITE ELEMENT METHODS FOR QUADRATIC CONVECTION DIFFUSION OPTIMAL CONTROL PROBLEMS
A POSTERIORI ERROR ESTIMATES OF TRIANGULAR MIXED FINITE ELEMENT METHODS FOR QUADRATIC CONVECTION DIFFUSION OPTIMAL CONTROL PROBLEMS Z. LU Communicated by Gabriela Marinoschi In this paper, we discuss a
More information