Advanced near-wall heat transfer modeling for in-cylinder flows
|
|
- Jesse Barton
- 6 years ago
- Views:
Transcription
1 International Multidimensional Engine Modeling User s Group Meeting at the SAE Congress April 20, 2015 Detroit, MI S. Šarić, B. Basara AVL List GmbH Advanced near-wall heat transfer modeling for in-cylinder flows 1 Abstract Most of the existing wall heat transfer models employed for in-cylinder flow simulations are not capable of predicting the history and peak value of the heat flux. More comprehensive models that account for density and property variations rely mainly on the standard or low-reynolds number variants of k-ε turbulence model. Presently applied mesh resolutions already allow for first near-wall computational cells reaching the buffer or locally even viscous/conductive sublayer, thus increasing importance of more sophisticated modeling of near-wall transport phenomena. The present approach relies on the k-ζ-f turbulence model which is capable of capturing turbulent stress anisotropy near wall and predicting heat transfer with more fidelity. A compressible wall function of Han and Reitz is formulated in the framework of hybrid wall treatment. The model is validated against spark ignition (SI) engine heat transfer measurements. Predicted wall heat flux evolutions on the cylinder head exhibit very good agreement with the experimental data, being superior to similar numerical predictions available in the published literature. 2 Introduction The existing wall heat transfer models (temperature wall functions) for in-cylinder flows are usually employed in conjunction with standard or low-reynolds number variants of k-ε turbulence model. Irrespective of complexity of the heat transfer model, its performance strongly depends on capability of the underlying turbulence model to capture near-wall transport phenomena. Numerous engine simulations, however, still employ a standard modelling approach for turbulence (e.g. standard k-ε) and wall heat transfer (e.g. temperature wall function of Jayatilleke (1969)) models which do not account for near-wall effects (viscous and non-viscous), variable properties and increase of the turbulent Prandtl number. Consequently, this results in substantial under-predictions (log-law region) or over-predictions (viscous/conductive sub-layer) of wall heat transfer. The previous work pertinent to engine heat transfer modeling is scrutinized in the publications of Rakopoulos et al. (2010) and Nuutinen et al. (2014). Rakopoulos et al. (2010) have evaluated the most popular heat transfer formulations used in commercial and research computational fluid dynamics (CFD) codes. Under-predictions of the measured heat flux peak values by 35-50% revealed weakness of incompressible temperature wall functions, whereas the 1
2 model of Han and Reitz (1997) was found to be the best compromise between simplicity and accuracy. Apart from variable density effects already observed by Han and Reitz (1997) and Angelberger et al. (1997), Nuutinen at al. (2014) incorporated combined variable properties effects on heat transfer and near-wall turbulence modifications in their imbalance wall function. The present work is based on more advanced, k-ζ-f turbulence model which allows integration to the wall, with incorporated molecular and wall-blocking modifications (Hanjalić et al., 2004). Consequently, the model is capable of capturing turbulent stress anisotropy near wall and predicting heat transfer with more fidelity. Hybrid wall treatment in AVL FIRE (2013) is extended to the temperature wall function of Han and Reitz. Predictive capability of the hybrid approach is validated against the spark-ignition (SI) engine heat transfer measurements of Alkidas and Myers (1982). 3 Modeling Approach The k-ζ-f RANS model employed in the present work relies on the elliptic relaxation concept providing a continuous modification of the homogeneous pressure-strain process as the wall is approached to satisfy the wall conditions, thus avoiding the need for any wall topology parameter. The variable ζ represents the ratio v 2 / k ( v 2 is a scalar property in the Durbin s v2 f model (1991), which reduces to the wall-normal stress in the near-wall region) providing more convenient formulation of the equation for ζ and especially of the wall boundary conditions for the elliptic function f. Hanjalić et al. (2004) demonstrated that the model is numerically very robust and more accurate compared to the simpler two-equation eddy viscosity models. Readers are referred to the original publications of Hanjalić et al. (2004), Popovac and Hanjalić (2007) and Basara (2006) for more specific details about the model developments. Han and Reitz (1997) derived the compressible wall function T = 2.1ln y (1) + + used to model the wall heat flux as q w * T ρcpu T ln Tw = + 2.1ln y Note that the published model formulation was recommended for both turbulent and laminar regimes, i.e. irrespective of y +. Accordingly, among other authors, Rakopoulos et al. (2010) in their evaluation of the existing heat transfer models, point out validity of the wall function of Han and Reitz for all y +. Due to some ambiguities in the original publication, this model (T + ) is practically used irrespective of y +, relying on the advanced near-wall treatment applied only to the momentum and turbulent equations. Consistent implementation of the model would require consideration of the near-wall formulation of the temperature wall function. As discussed by Šarić and Basara (2015), the following two-layer formulation T = 7.415arctan(0.089 y 0.093) (3) + + nw is used as a reference (Figure 1) for the model implementation in the framework of hybrid wall treatment. (2) 2
3 Figure 1: Hybrid formulation of the temperature wall function This method blends the integration up to the wall (exact boundary conditions) with the high- Reynolds number wall functions, enabling well-defined boundary conditions irrespective of the position of the wall-closest computational node. The hybrid wall treatment employed here represents a somewhat simplified approach (AVL FIRE, 2013). Whereas the original compound wall treatment of Popovac and Hanjalić (2007) includes the tangential pressure gradient and convection terms, a simpler approach utilizing the standard wall functions as the upper bound is used presently. Another departure from the original formulation is pertinent to the calculation of the dissipation rate as proposed by Basara (2006). Regarding a wavy profile in Figure 1 the blending function could certainly be tuned to yield smoother distribution in the buffer layer (e.g. Γ mod = 0.003( y + ) 4 / (1+ y + )). However, the same blending principle of Kader (1981) is intentionally retained and now extended to the compressible wall function of Han and Reitz which is implemented implicitly via effective enthalpy diffusion coefficients (µy + /T + ). The hybrid model depicted in Figure 1 can be expressed as follows: Γ + hyb Pr (2.1ln 2.5) Γ T = y e + y + e (4) with the blending coefficient (Kader,1981) as a function of the normalized distance to the wall: + 4 (Pr y ) Γ = 0.01 (5) Pr y 4 Results The hybrid model is validated against the experimental measurements of by Alkidas and Myers (1982) who investigated heat transfer in a premixed charge spark ignition (SI) engine. Employing the total enthalpy formulation for energy equation and using the ECFM3Z model (Colin and Benkenida, 2004, AVL FIRE, 2013) to model combustion phenomena, a simple SI engine geometry was simulated (Šarić and Basara, 2015). In many practical engine simulations, the wall function of Jayatilleke (1969) is employed, moreover, this isothermal/incompressible wall function is often also used in conjunction with the standard k-ɛ turbulence model. Although the mean cylinder pressure can be reproduced (Figure 2a), heat transfer is substantially under-predicted as illustrated in Figure 2b. In this particular case, more advanced turbulence modeling and wall 3
4 treatment (k-ζ-f-jt-hyb) brings certain benefit, however, the measured wall heat flux is still underpredicted by almost 50%. Interestingly, if the same modeling is applied outside its applicability range (e.g. on meshes with y + <10, Figure 3a), one can observe better agreement with the measured data in Figure 3b. However, this behavior is fortuitous, resulting actually from turbulence and heat transfer over-predictions. This is caused by improper near-wall turbulence modeling (standard k-ɛ) and deficiency of the wall function of Jayatilleke which cannot account for increase of the turbulent Prandtl number close to the wall (y + <10). (a) Figure 2: (baseline mesh) Captured mean cylinder pressure (a) and under-predictions of the measured wall heat fluxes by the incompressible temperature wall function of Jayatilleke (a) Figure 3: (refined mesh) Evolution of local y+ at the cylinder head surface (a) and fortuitously better predictions of the measured wall heat fluxes by the standard k-ɛ Jayatilleke model For the sake of illustration, Figure 4a compares the wall heat flux history predicted by the present model to the available experimental data at the radial location r=37.3mm. Clearly, the hybrid model outperforms the standard Han and Reitz wall function. This behavior is expected if one examines the evolution of the near-wall y + at this measuring location (Figure 4b), indicating that y + resides in the buffer layer for CA larger than 0. Since heat transfer is governed by temperature gradient and the enthalpy diffusion coefficient, being inversely proportional to T + hyb, the results are consistent with the non-dimensional temperature profiles displayed in Figure 1. Although the twolayer formulation yields improved results as well, for the reasons explained before it is used here only as a reference in order to verify the hybrid model implementation. The present hybrid model 4
5 is evidently superior to the standard Han and Reitz wall function for cases involving fine mesh resolutions with non-dimensional wall distance y + ranging from the buffer region down to the viscous/conduction sub-layer. Predicted wall heat flux evolutions on the cylinder head exhibit very good agreement with the experimental data as documented in Figure 5. Figure 4: Comparative assessment of different model formulations on the cylinder head surface at radial position r=37.3mm (a) with the evolution of local y + at the cylinder head surface (a) Figure 5: Improved predictions of wall heat fluxes employing the hybrid model formulation 5
6 5 Conclusions The underlying hybrid wall treatment in AVL FIRE was extended to the model of Han and Reitz and validated against the spark-ignition (SI) engine heat transfer measurements. The resulting hybrid model is superior to the standard Han and Reitz wall function for cases involving meshes with y + ranging from the buffer region down to the viscous/conduction sub-layer. Predicted wall heat flux evolutions on the cylinder head exhibit very good agreement with the experimental data, clearly demonstrating potential advantages of the hybrid wall heat transfer approach in conjunction with the advanced turbulence model. 6 References [1] Jayatilleke C. The influence of Prandtl number and surface roughness on the resistanceof the laminar sublayerto momentum and heat transfer. Prog Heat Mass Transfer 1: , 1969 [2] Rakopoulos, C.,D., Kosmadakis, G.M., and Pariotis, E.G.: "Critical evaluation of current heat transfer models used in CFD in-cylinder engine simulations and establishment of a comprehensive wall-function formulation", Journal of Applied Energy, Vol. 87, pp , 2010 [3] Nuutinen, M.A., Kaario, O.T., Vuorinen, V.A., Nwosu, P.N., and Larmi, M.: Imbalance wall functions with density and material property variation effects applied to engine heat transfer computational fluid dynamics simulations, Int. J. of Engine Research, Vol. 15(3), pp , 2014 [4] Han, R. and Reitz, R.: A temperature wall function formulation for variable-density turbulent flows with application to engine convective heat transfer modeling, Int. J. Heat Mass Transfer Vol. 40, No 3, pp , 1997 [5] Angelberger, C, Poinsot, T, and Delhay, B.: Improving near-wall combustion and wall heat transfer modeling in SI engine computations. SAE technical paper , pp ,1997 [6] Hanjalić, K., Popovac, M., and Hadžiabdić, M.: A robust near-wall elliptic relaxation eddy-viscosity turbulence model for CFD. Int. J. Heat and Fluid Flow, Vol. 25, pp , 2004 [7] AVL List GmbH: Main Program, FIRE version 2013 manual, Graz, Austria, [8] Alkidas, A.C. and Myers, J.P.: Transient heat-flux measurements in the combustion chamber of a sparkignition engine. J. Heat Transfer: T ASME Vol. 104, pp , 1982, [9] Durbin, P.A.: Near-Wall Turbulence Closure Modelling Without Damping Functions, Theoret. Comput. Fluid Dynamic., Vol. 3, pp. 1-13, 1991 [10] Popovac, M. and Hanjalić, K.: Compound Wall Treatment for RANS Computation of Complex Turbulent Flows and Heat Transfer, Flow, Turbulence and Combustion, Vol. 78, pp , 2007 [11] Basara, B.: An Eddy Viscosity Transport Model Based on Elliptic Relaxation Approach, AIAA Journal, Vol. 44, pp , 2006 [12] Šarić.S and Basara, B.: A Hybrid Wall Heat Transfer Model for IC Engine Simulations," SAE Int. J. Engines 8(2):2015,doi: / [13] Kader, B.A.: Temperature and Concentration Profiles in Fully Turbulent Boundary Layers, Int. J. Heat and Mass Transfer, Vol. 24, pp , 1981 [14] Colin, O. and Benkenida, A.: The 3-Zones Extended Coherent Flame Model (ECFM3Z) for computing Premixed/Diffusion Combustion, Oil & Gas Science and Technology Rev IFP, Vol. 59, No. 6,pp ,
A Comprehensive Method for the Characterization of Engine Heat Rejection
A Spin-Off Company of A Comprehensive Method for the Characterization of Engine Heat Rejection Giuseppe Cicalese Stefano Fontanesi Fabio Berni Genesis of the methodology Methodology guidelines In-Cylinder
More informationJournal of Asian Scientific Research THE FLAME PROPAGATION OF VARIOUS FUELS IN A PARTICULAR COMBUSTION CHAMBER OF 4.-VALVE ENGINES
Journal of Asian Scientific Research ISSN(e): 2223-1331/ISSN(p): 2226-5724 URL: www.aessweb.com THE FLAME PROPAGATION OF VARIOUS FUELS IN A PARTICULAR COMBUSTION CHAMBER OF 4.-VALVE ENGINES Zoran Jovanovic
More informationTransported PDF Calculations of Combustion in Compression- Ignition Engines
International Multidimensional Engine Modeling User s Group Meeting at the SAE Congress Detroit, MI 15 April 2013 Transported PDF Calculations of Combustion in Compression- Ignition Engines V. Raj Mohan
More informationA NOVEL VLES MODEL FOR TURBULENT FLOW SIMULATIONS
June 30 - July 3, 2015 Melbourne, Australia 9 7B-4 A NOVEL VLES MODEL FOR TURBULENT FLOW SIMULATIONS C.-Y. Chang, S. Jakirlić, B. Krumbein and C. Tropea Institute of Fluid Mechanics and Aerodynamics /
More informationA NUMERICAL ANALYSIS OF COMBUSTION PROCESS IN AN AXISYMMETRIC COMBUSTION CHAMBER
SCIENTIFIC RESEARCH AND EDUCATION IN THE AIR FORCE-AFASES 2016 A NUMERICAL ANALYSIS OF COMBUSTION PROCESS IN AN AXISYMMETRIC COMBUSTION CHAMBER Alexandru DUMITRACHE*, Florin FRUNZULICA ** *Institute of
More informationROBUST EDDY VISCOSITY TURBULENCE MODELING WITH ELLIPTIC RELAXATION FOR EXTERNAL BUILDING FLOW ANALYSIS
August 11 13, ROBUST EDDY VISCOSITY TURBULENCE MODELING WITH ELLIPTIC RELAXATION FOR EXTERNAL BUILDING FLOW ANALYSIS Mirza Popovac AIT Austrian Institute of Technology Österreichisches Forschungs- und
More informationDetailed Chemical Kinetics in Multidimensional CFD Using Storage/Retrieval Algorithms
13 th International Multidimensional Engine Modeling User's Group Meeting, Detroit, MI (2 March 23) Detailed Chemical Kinetics in Multidimensional CFD Using Storage/Retrieval Algorithms D.C. Haworth, L.
More informationMODELLING TURBULENT HEAT FLUXES USING THE ELLIPTIC BLENDING APPROACH FOR NATURAL CONVECTION
MODELLING TURBULENT HEAT FLUXES USING THE ELLIPTIC BLENDING APPROACH FOR NATURAL CONVECTION F. Dehoux Fluid Mechanics, Power generation and Environment Department MFEE Dept.) EDF R&D Chatou, France frederic.dehoux@edf.fr
More informationWall treatments and wall functions
Wall treatments and wall functions A wall treatment is the set of near-wall modelling assumptions for each turbulence model. Three types of wall treatment are provided in FLUENT, although all three might
More informationEVALUATION OF FOUR TURBULENCE MODELS IN THE INTERACTION OF MULTI BURNERS SWIRLING FLOWS
EVALUATION OF FOUR TURBULENCE MODELS IN THE INTERACTION OF MULTI BURNERS SWIRLING FLOWS A Aroussi, S Kucukgokoglan, S.J.Pickering, M.Menacer School of Mechanical, Materials, Manufacturing Engineering and
More informationNumerical Methods in Aerodynamics. Turbulence Modeling. Lecture 5: Turbulence modeling
Turbulence Modeling Niels N. Sørensen Professor MSO, Ph.D. Department of Civil Engineering, Alborg University & Wind Energy Department, Risø National Laboratory Technical University of Denmark 1 Outline
More informationA TURBULENT HEAT FLUX TWO EQUATION θ 2 ε θ CLOSURE BASED ON THE V 2F TURBULENCE MODEL
TASK QUARTERLY 7 No 3 (3), 375 387 A TURBULENT HEAT FLUX TWO EQUATION θ ε θ CLOSURE BASED ON THE V F TURBULENCE MODEL MICHAŁ KARCZ AND JANUSZ BADUR Institute of Fluid-Flow Machinery, Polish Academy of
More information3. FORMS OF GOVERNING EQUATIONS IN CFD
3. FORMS OF GOVERNING EQUATIONS IN CFD 3.1. Governing and model equations in CFD Fluid flows are governed by the Navier-Stokes equations (N-S), which simpler, inviscid, form is the Euler equations. For
More informationINVESTIGATION OF THE FLOW OVER AN OSCILLATING CYLINDER WITH THE VERY LARGE EDDY SIMULATION MODEL
ECCOMAS Congress 2016 VII European Congress on Computational Methods in Applied Sciences and Engineering M. Papadrakakis, V. Papadopoulos, G. Stefanou, V. Plevris (eds.) Crete Island, Greece, 5 10 June
More informationOn the transient modelling of impinging jets heat transfer. A practical approach
Turbulence, Heat and Mass Transfer 7 2012 Begell House, Inc. On the transient modelling of impinging jets heat transfer. A practical approach M. Bovo 1,2 and L. Davidson 1 1 Dept. of Applied Mechanics,
More informationMODELLING OF INFLUENCE OF TURBULENT TRANSITION ON HEAT TRANSFER CONDITIONS KRZYSZTOF BOCHON, WŁODZIMIERZ WRÓBLEWSKI
TASK QUARTERLY 12 No 3, 173 184 MODELLING OF INFLUENCE OF TURBULENT TRANSITION ON HEAT TRANSFER CONDITIONS KRZYSZTOF BOCHON, WŁODZIMIERZ WRÓBLEWSKI AND SŁAWOMIR DYKAS Institute of Power Engineering and
More informationStudies on flow through and around a porous permeable sphere: II. Heat Transfer
Studies on flow through and around a porous permeable sphere: II. Heat Transfer A. K. Jain and S. Basu 1 Department of Chemical Engineering Indian Institute of Technology Delhi New Delhi 110016, India
More informationSteady state operation simulation of the Francis- 99 turbine by means of advanced turbulence models
Journal of Physics: Conference Series PAPER OPEN ACCESS Steady state operation simulation of the Francis- 99 turbine by means of advanced turbulence models To cite this article: A Gavrilov et al 2017 J.
More informationHeat Transfer from An Impingement Jet onto A Heated Half-Prolate Spheroid Attached to A Heated Flat Plate
1 nd International Conference on Environment and Industrial Innovation IPCBEE vol.35 (1) (1) IACSIT Press, Singapore Heat Transfer from An Impingement Jet onto A Heated Half-Prolate Spheroid Attached to
More informationOpenFOAM selected solver
OpenFOAM selected solver Roberto Pieri - SCS Italy 16-18 June 2014 Introduction to Navier-Stokes equations and RANS Turbulence modelling Numeric discretization Navier-Stokes equations Convective term {}}{
More informationDevelopment of an In-Cylinder Heat Transfer Correlation for Reciprocating Compressors
Purdue University Purdue e-pubs International Compressor Engineering Conference School of Mechanical Engineering 2012 Development of an In-Cylinder Heat Transfer Correlation for Reciprocating Compressors
More informationProbability density function (PDF) methods 1,2 belong to the broader family of statistical approaches
Joint probability density function modeling of velocity and scalar in turbulence with unstructured grids arxiv:6.59v [physics.flu-dyn] Jun J. Bakosi, P. Franzese and Z. Boybeyi George Mason University,
More informationProcess Chemistry Toolbox - Mixing
Process Chemistry Toolbox - Mixing Industrial diffusion flames are turbulent Laminar Turbulent 3 T s of combustion Time Temperature Turbulence Visualization of Laminar and Turbulent flow http://www.youtube.com/watch?v=kqqtob30jws
More informationTurbulent Boundary Layers & Turbulence Models. Lecture 09
Turbulent Boundary Layers & Turbulence Models Lecture 09 The turbulent boundary layer In turbulent flow, the boundary layer is defined as the thin region on the surface of a body in which viscous effects
More informationEffect of near-wall treatments on airflow simulations
Proceedings of 29 International Conference on Computational Methods for Energy Engineering and Environment: ICCM3E. Sousse, Tunisia, 2-22 November, 29, pp. Effect of near-wall treatments on airflow simulations
More informationA SEAMLESS HYBRID RANS/LES MODEL WITH DYNAMIC REYNOLDS-STRESS CORRECTION FOR HIGH REYNOLDS
A SEAMS HYBRID RANS/ MODEL WITH DYNAMIC REYNOLDS-STRESS CORRECTION FOR HIGH REYNOLDS NUMBER FLOWS ON COARSE GRIDS P. Nguyen 1, J. Uribe 2, I. Afgan 1 and D. Laurence 1 1 School of Mechanical, Aerospace
More informationLarge-eddy simulation of an industrial furnace with a cross-flow-jet combustion system
Center for Turbulence Research Annual Research Briefs 2007 231 Large-eddy simulation of an industrial furnace with a cross-flow-jet combustion system By L. Wang AND H. Pitsch 1. Motivation and objectives
More informationNUMERICAL SIMULATION OF LDI COMBUSTOR WITH DISCRETE-JET SWIRLERS USING RE-STRESS MODEL IN THE KIVA CODE
NUMERICAL SIMULATION OF LDI COMBUSTOR WITH DISCRETE-JET SWIRLERS USING RE-STRESS MODEL IN THE KIVA CODE S. L. Yang, C. Y. Teo, and Y. K. Siow Department of Mechanical Engineering Engineering Mechanics
More informationComputation of Incompressible Flows: SIMPLE and related Algorithms
Computation of Incompressible Flows: SIMPLE and related Algorithms Milovan Perić CoMeT Continuum Mechanics Technologies GmbH milovan@continuummechanicstechnologies.de SIMPLE-Algorithm I - - - Consider
More informationPrinciples of Convection
Principles of Convection Point Conduction & convection are similar both require the presence of a material medium. But convection requires the presence of fluid motion. Heat transfer through the: Solid
More informationDEVELOPMENT OF CFD MODEL FOR A SWIRL STABILIZED SPRAY COMBUSTOR
DRAFT Proceedings of ASME IMECE: International Mechanical Engineering Conference & Exposition Chicago, Illinois Nov. 5-10, 2006 IMECE2006-14867 DEVELOPMENT OF CFD MODEL FOR A SWIRL STABILIZED SPRAY COMBUSTOR
More informationComputation of turbulent natural convection with buoyancy corrected second moment closure models
Computation of turbulent natural convection with buoyancy corrected second moment closure models S. Whang a, H. S. Park a,*, M. H. Kim a, K. Moriyama a a Division of Advanced Nuclear Engineering, POSTECH,
More informationThere are no simple turbulent flows
Turbulence 1 There are no simple turbulent flows Turbulent boundary layer: Instantaneous velocity field (snapshot) Ref: Prof. M. Gad-el-Hak, University of Notre Dame Prediction of turbulent flows standard
More informationNumerical simulations of heat transfer in plane channel flow
Numerical simulations of heat transfer in plane channel flow Najla EL GHARBI 1, 3, a, Rafik ABSI 2, b and Ahmed BENZAOUI 3, c 1 Renewable Energy Development Center, BP 62 Bouzareah 163 Algiers, Algeria
More informationSimulating Drag Crisis for a Sphere Using Skin Friction Boundary Conditions
Simulating Drag Crisis for a Sphere Using Skin Friction Boundary Conditions Johan Hoffman May 14, 2006 Abstract In this paper we use a General Galerkin (G2) method to simulate drag crisis for a sphere,
More informationMOMENTUM TRANSPORT Velocity Distributions in Turbulent Flow
TRANSPORT PHENOMENA MOMENTUM TRANSPORT Velocity Distributions in Turbulent Flow Introduction to Turbulent Flow 1. Comparisons of laminar and turbulent flows 2. Time-smoothed equations of change for incompressible
More informationNumerical investigation of swirl flow inside a supersonic nozzle
Advances in Fluid Mechanics IX 131 Numerical investigation of swirl flow inside a supersonic nozzle E. Eslamian, H. Shirvani & A. Shirvani Faculty of Science and Technology, Anglia Ruskin University, UK
More informationCalculations on a heated cylinder case
Calculations on a heated cylinder case J. C. Uribe and D. Laurence 1 Introduction In order to evaluate the wall functions in version 1.3 of Code Saturne, a heated cylinder case has been chosen. The case
More informationCFD analysis of the transient flow in a low-oil concentration hydrocyclone
CFD analysis of the transient flow in a low-oil concentration hydrocyclone Paladino, E. E. (1), Nunes, G. C. () and Schwenk, L. (1) (1) ESSS Engineering Simulation and Scientific Software CELTA - Rod SC-41,
More informationIntroduction to Heat and Mass Transfer. Week 12
Introduction to Heat and Mass Transfer Week 12 Next Topic Convective Heat Transfer» Heat and Mass Transfer Analogy» Evaporative Cooling» Types of Flows Heat and Mass Transfer Analogy Equations governing
More informationThe mean shear stress has both viscous and turbulent parts. In simple shear (i.e. U / y the only non-zero mean gradient):
8. TURBULENCE MODELLING 1 SPRING 2019 8.1 Eddy-viscosity models 8.2 Advanced turbulence models 8.3 Wall boundary conditions Summary References Appendix: Derivation of the turbulent kinetic energy equation
More informationLecture 8 Laminar Diffusion Flames: Diffusion Flamelet Theory
Lecture 8 Laminar Diffusion Flames: Diffusion Flamelet Theory 8.-1 Systems, where fuel and oxidizer enter separately into the combustion chamber. Mixing takes place by convection and diffusion. Only where
More informationProspects for High-Speed Flow Simulations
Prospects for High-Speed Flow Simulations Graham V. Candler Aerospace Engineering & Mechanics University of Minnesota Support from AFOSR and ASDR&E Future Directions in CFD Research: A Modeling & Simulation
More informationTOPICAL PROBLEMS OF FLUID MECHANICS 97
TOPICAL PROBLEMS OF FLUID MECHANICS 97 DOI: http://dx.doi.org/10.14311/tpfm.2016.014 DESIGN OF COMBUSTION CHAMBER FOR FLAME FRONT VISUALISATION AND FIRST NUMERICAL SIMULATION J. Kouba, J. Novotný, J. Nožička
More informationLecture 9 Laminar Diffusion Flame Configurations
Lecture 9 Laminar Diffusion Flame Configurations 9.-1 Different Flame Geometries and Single Droplet Burning Solutions for the velocities and the mixture fraction fields for some typical laminar flame configurations.
More informationPressure-velocity correction method Finite Volume solution of Navier-Stokes equations Exercise: Finish solving the Navier Stokes equations
Today's Lecture 2D grid colocated arrangement staggered arrangement Exercise: Make a Fortran program which solves a system of linear equations using an iterative method SIMPLE algorithm Pressure-velocity
More informationNumerical analysis of fluid flow and heat transfer in 2D sinusoidal wavy channel
Numerical analysis of fluid flow and heat transfer in 2D sinusoidal wavy channel Arunanshu Chakravarty 1* 1 CTU in Prague, Faculty of Mechanical Engineering, Department of Process Engineering,Technická
More informationOptimizing calculation costs of tubulent flows with RANS/LES methods
Optimizing calculation costs of tubulent flows with RANS/LES methods Investigation in separated flows C. Friess, R. Manceau Dpt. Fluid Flow, Heat Transfer, Combustion Institute PPrime, CNRS University
More informationProblem 4.3. Problem 4.4
Problem 4.3 Problem 4.4 Problem 4.5 Problem 4.6 Problem 4.7 This is forced convection flow over a streamlined body. Viscous (velocity) boundary layer approximations can be made if the Reynolds number Re
More informationFluid Mechanics. Chapter 9 Surface Resistance. Dr. Amer Khalil Ababneh
Fluid Mechanics Chapter 9 Surface Resistance Dr. Amer Khalil Ababneh Wind tunnel used for testing flow over models. Introduction Resistances exerted by surfaces are a result of viscous stresses which create
More informationElliptic relaxation for near wall turbulence models
Elliptic relaxation for near wall turbulence models J.C. Uribe University of Manchester School of Mechanical, Aerospace & Civil Engineering Elliptic relaxation for near wall turbulence models p. 1/22 Outline
More informationModel Studies on Slag-Metal Entrainment in Gas Stirred Ladles
Model Studies on Slag-Metal Entrainment in Gas Stirred Ladles Anand Senguttuvan Supervisor Gordon A Irons 1 Approach to Simulate Slag Metal Entrainment using Computational Fluid Dynamics Introduction &
More informationEMISSION PREDICTIONS IN DIESEL ENGINES USING A NON-EQUILIBRIUM TURBULENCE DISSIPATION CORRECTION FOR THE k-ε MODEL
Twelfth International Multidimensional Engine Modeling Meeting at the SAE Congress March 3, 2002, Detroit, Michigan EMISSION PREDICTIONS IN DIESEL ENGINES USING A NON-EQUILIBRIUM TURBULENCE DISSIPATION
More informationInsights into Model Assumptions and Road to Model Validation for Turbulent Combustion
Insights into Model Assumptions and Road to Model Validation for Turbulent Combustion Venke Sankaran AFRL/RQR 2015 AFRL/RQR Basic Research Review UCLA Jan 20, 2015 AFTC PA Release# 15011, 16 Jan 2015 Goals
More informationNumerical Heat and Mass Transfer
Master Degree in Mechanical Engineering Numerical Heat and Mass Transfer 19 Turbulent Flows Fausto Arpino f.arpino@unicas.it Introduction All the flows encountered in the engineering practice become unstable
More informationADAPTATION OF THE REYNOLDS STRESS TURBULENCE MODEL FOR ATMOSPHERIC SIMULATIONS
ADAPTATION OF THE REYNOLDS STRESS TURBULENCE MODEL FOR ATMOSPHERIC SIMULATIONS Radi Sadek 1, Lionel Soulhac 1, Fabien Brocheton 2 and Emmanuel Buisson 2 1 Laboratoire de Mécanique des Fluides et d Acoustique,
More informationRANS simulations of rotating flows
Center for Turbulence Research Annual Research Briefs 1999 257 RANS simulations of rotating flows By G. Iaccarino, A. Ooi, B. A. Pettersson Reif AND P. Durbin 1. Motivation and objectives Numerous experimental
More informationPHYSICAL MECHANISM OF CONVECTION
Tue 8:54:24 AM Slide Nr. 0 of 33 Slides PHYSICAL MECHANISM OF CONVECTION Heat transfer through a fluid is by convection in the presence of bulk fluid motion and by conduction in the absence of it. Chapter
More informationρ t + (ρu j ) = 0 (2.1) x j +U j = 0 (2.3) ρ +ρ U j ρ
Chapter 2 Mathematical Models The following sections present the equations which are used in the numerical simulations documented in this thesis. For clarity, equations have been presented in Cartesian
More informationThermo Mechanical Analysis of AV1 Diesel Engine Piston using FEM
Journal of Advanced Engineering Research ISSN: 2393-8447 Volume 2, Issue 1, 2015, pp.23-28 Thermo Mechanical Analysis of AV1 Diesel Engine Piston using FEM Subodh Kumar Sharma 1, *, P. K. Saini 2, N. K.
More informationDARS overview, IISc Bangalore 18/03/2014
www.cd-adapco.com CH2O Temperatur e Air C2H4 Air DARS overview, IISc Bangalore 18/03/2014 Outline Introduction Modeling reactions in CFD CFD to DARS Introduction to DARS DARS capabilities and applications
More informationExplicit algebraic Reynolds stress models for internal flows
5. Double Circular Arc (DCA) cascade blade flow, problem statement The second test case deals with a DCA compressor cascade, which is considered a severe challenge for the CFD codes, due to the presence
More informationLES modeling of heat and mass transfer in turbulent recirculated flows E. Baake 1, B. Nacke 1, A. Umbrashko 2, A. Jakovics 2
MAGNETOHYDRODYNAMICS Vol. 00 (1964), No. 00, pp. 1 5 LES modeling of heat and mass transfer in turbulent recirculated flows E. Baake 1, B. Nacke 1, A. Umbrashko 2, A. Jakovics 2 1 Institute for Electrothermal
More informationIntroduction of compressible turbulence
Introduction of compressible turbulence 1 Main topics Derive averaged equations for compressible turbulence Introduce a math. technique to perform averaging in presence of density variation Favre average
More informationA Numerical Study of Convective Heat Transfer in the Compression Chambers of Scroll Compressors
Purdue University Purdue e-pubs International Compressor Engineering Conference School of Mechanical Engineering 2012 A Numerical Study of Convective Heat Transfer in the Compression Chambers of Scroll
More informationA PARAMETRIC DESIGN OF COMPACT EXHAUST MANIFOLD JUNCTION IN HEAVY DUTY DIESEL ENGINE USING COMPUTATIONAL FLUID DYNAMICS CODES
THERMAL SCIENCE, Year 011, Vol. 15, No. 4, pp. 103-1033 103 A PARAMETRIC DESIGN OF COMPACT EXHAUST MANIFOLD JUNCTION IN HEAVY DUTY DIESEL ENGINE USING COMPUTATIONAL FLUID DYNAMICS CODES by Hessamedin NAEIMI
More informationUNIT II CONVECTION HEAT TRANSFER
UNIT II CONVECTION HEAT TRANSFER Convection is the mode of heat transfer between a surface and a fluid moving over it. The energy transfer in convection is predominately due to the bulk motion of the fluid
More informationColloquium FLUID DYNAMICS 2012 Institute of Thermomechanics AS CR, v.v.i., Prague, October 24-26, 2012 p.
Colloquium FLUID DYNAMICS 212 Institute of Thermomechanics AS CR, v.v.i., Prague, October 24-26, 212 p. ON A COMPARISON OF NUMERICAL SIMULATIONS OF ATMOSPHERIC FLOW OVER COMPLEX TERRAIN T. Bodnár, L. Beneš
More informationSimplified Model of WWER-440 Fuel Assembly for ThermoHydraulic Analysis
1 Portál pre odborné publikovanie ISSN 1338-0087 Simplified Model of WWER-440 Fuel Assembly for ThermoHydraulic Analysis Jakubec Jakub Elektrotechnika 13.02.2013 This work deals with thermo-hydraulic processes
More informationME 144: Heat Transfer Introduction to Convection. J. M. Meyers
ME 144: Heat Transfer Introduction to Convection Introductory Remarks Convection heat transfer differs from diffusion heat transfer in that a bulk fluid motion is present which augments the overall heat
More informationAN UNCERTAINTY ESTIMATION EXAMPLE FOR BACKWARD FACING STEP CFD SIMULATION. Abstract
nd Workshop on CFD Uncertainty Analysis - Lisbon, 19th and 0th October 006 AN UNCERTAINTY ESTIMATION EXAMPLE FOR BACKWARD FACING STEP CFD SIMULATION Alfredo Iranzo 1, Jesús Valle, Ignacio Trejo 3, Jerónimo
More informationImpact of numerical method on auto-ignition in a temporally evolving mixing layer at various initial conditions
Journal of Physics: Conference Series PAPER OPEN ACCESS Impact of numerical method on auto-ignition in a temporally evolving mixing layer at various initial conditions To cite this article: A Rosiak and
More informationTurbulence Modeling I!
Outline! Turbulence Modeling I! Grétar Tryggvason! Spring 2010! Why turbulence modeling! Reynolds Averaged Numerical Simulations! Zero and One equation models! Two equations models! Model predictions!
More informationTurbulence Modeling. Cuong Nguyen November 05, The incompressible Navier-Stokes equations in conservation form are u i x i
Turbulence Modeling Cuong Nguyen November 05, 2005 1 Incompressible Case 1.1 Reynolds-averaged Navier-Stokes equations The incompressible Navier-Stokes equations in conservation form are u i x i = 0 (1)
More informationAccommodating LES to high Re numbers: RANS-based, or a new strategy?
Symposium on Methods 14-15 July 2005, FOI, Stockholm, Sweden, Accommodating LES to high Re numbers: RANS-based, or a new strategy? K. Hanjalić Delft University of Technology, The Netherlands Guest Professor,
More informationComparison of Turbulence Models in the Flow over a Backward-Facing Step Priscila Pires Araujo 1, André Luiz Tenório Rezende 2
Comparison of Turbulence Models in the Flow over a Backward-Facing Step Priscila Pires Araujo 1, André Luiz Tenório Rezende 2 Department of Mechanical and Materials Engineering, Military Engineering Institute,
More information4.2 Concepts of the Boundary Layer Theory
Advanced Heat by Amir Faghri, Yuwen Zhang, and John R. Howell 4.2 Concepts of the Boundary Layer Theory It is difficult to solve the complete viscous flow fluid around a body unless the geometry is very
More informationThe effect of geometric parameters on the head loss factor in headers
Fluid Structure Interaction V 355 The effect of geometric parameters on the head loss factor in headers A. Mansourpour & S. Shayamehr Mechanical Engineering Department, Azad University of Karaj, Iran Abstract
More informationTransactions on Engineering Sciences vol 5, 1994 WIT Press, ISSN
Heat transfer at the outer surface of a rotating cylinder in the presence of axial flows R. Smyth & P. Zurita Department of Mechanical and Process Engineering, University of Sheffield, f. 0. Boz #00, Moppm
More informationMostafa Momen. Project Report Numerical Investigation of Turbulence Models. 2.29: Numerical Fluid Mechanics
2.29: Numerical Fluid Mechanics Project Report Numerical Investigation of Turbulence Models Mostafa Momen May 2015 Massachusetts Institute of Technology 1 Numerical Investigation of Turbulence Models Term
More informationSimulation of Turbulent Lifted Flames and their Transient Propagation
25 th ICDERS August 2-7th, 2015 Leeds, UK Simulation of Turbulent Lifted Flames and their Transient Propagation S. Ruan, Z. Chen, N. Swaminathan University of Cambridge Cambridge, UK 1 Introduction Turbulent
More informationA first investigation on using a species reaction mechanism for flame propagation and soot emissions in CFD of SI engines
A first investigation on using a 1000+ species reaction mechanism for flame propagation and soot emissions in CFD of SI engines F.A. Tap *, D. Goryntsev, C. Meijer, A. Starikov Dacolt International BV
More informationTable of Contents. Foreword... xiii. Preface... xv
Table of Contents Foreword.... xiii Preface... xv Chapter 1. Fundamental Equations, Dimensionless Numbers... 1 1.1. Fundamental equations... 1 1.1.1. Local equations... 1 1.1.2. Integral conservation equations...
More informationCFD ANALYSIS OF TURBULENT THERMAL MIXING OF HOT AND COLD AIR IN AUTOMOBILE HVAC UNIT
ISTP-6, 005, PRAGUE 6 TH INTERNATIONAL SYMPOSIUM ON TRANSPORT PHENOMENA CFD ANALYSIS OF TURBULENT THERMAL MIING OF HOT AND COLD AIR IN AUTOMOBILE HVAC UNIT Hideo Asano ((, Kazuhiko Suga (3, Masafumi Hirota
More informationNONLINEAR FEATURES IN EXPLICIT ALGEBRAIC MODELS FOR TURBULENT FLOWS WITH ACTIVE SCALARS
June - July, 5 Melbourne, Australia 9 7B- NONLINEAR FEATURES IN EXPLICIT ALGEBRAIC MODELS FOR TURBULENT FLOWS WITH ACTIVE SCALARS Werner M.J. Lazeroms () Linné FLOW Centre, Department of Mechanics SE-44
More informationOn modeling pressure diusion. in non-homogeneous shear ows. By A. O. Demuren, 1 M. M. Rogers, 2 P. Durbin 3 AND S. K. Lele 3
Center for Turbulence Research Proceedings of the Summer Program 1996 63 On modeling pressure diusion in non-homogeneous shear ows By A. O. Demuren, 1 M. M. Rogers, 2 P. Durbin 3 AND S. K. Lele 3 New models
More informationCHAPTER 7 SEVERAL FORMS OF THE EQUATIONS OF MOTION
CHAPTER 7 SEVERAL FORMS OF THE EQUATIONS OF MOTION 7.1 THE NAVIER-STOKES EQUATIONS Under the assumption of a Newtonian stress-rate-of-strain constitutive equation and a linear, thermally conductive medium,
More informationChemical and Biomolecular Engineering 150A Transport Processes Spring Semester 2017
Chemical and Biomolecular Engineering 150A Transport Processes Spring Semester 2017 Objective: Text: To introduce the basic concepts of fluid mechanics and heat transfer necessary for solution of engineering
More information6.2 Governing Equations for Natural Convection
6. Governing Equations for Natural Convection 6..1 Generalized Governing Equations The governing equations for natural convection are special cases of the generalized governing equations that were discussed
More informationOn the numerical modelling of impinging jets heat transfer
THESIS FOR THE DEGREE OF LICENTIATE OF ENGINEERING in Thermo and Fluid Dynamics On the numerical modelling of impinging jets heat transfer M I R K O B O V O Department of Applied Mechanics CHALMERS UNIVERSITY
More information1. INTRODUCTION TO CFD SPRING 2019
1. INTRODUCTION TO CFD SPRING 2019 1.1 What is computational fluid dynamics? 1.2 Basic principles of CFD 1.3 Stages in a CFD simulation 1.4 Fluid-flow equations 1.5 The main discretisation methods Appendices
More informationA Computational Investigation of a Turbulent Flow Over a Backward Facing Step with OpenFOAM
206 9th International Conference on Developments in esystems Engineering A Computational Investigation of a Turbulent Flow Over a Backward Facing Step with OpenFOAM Hayder Al-Jelawy, Stefan Kaczmarczyk
More informationExercises in Combustion Technology
Exercises in Combustion Technology Exercise 4: Turbulent Premixed Flames Turbulent Flow: Task 1: Estimation of Turbulence Quantities Borghi-Peters diagram for premixed combustion Task 2: Derivation of
More informationModeling of Humidification in Comsol Multiphysics 4.4
Modeling of Humidification in Comsol Multiphysics 4.4 Indrajit Wadgaonkar *1 and Suresh Arikapudi 1 1 Tata Motors Ltd. Pimpri, Pune, India, 411018. *Corresponding author: Indrajit Wadgaonkar, Tata Motors
More informationCombustion MATHEMATICAL MODEL FOR TRANSIENT. S. M. Frolov Λ,F.S.Frolov Λ, and B. Basara y
Combustion MATHEMATICAL MODEL FOR TRANSIENT DROPLET VAPORIZATION S. M. Frolov Λ,F.S.Frolov Λ, and B. Basara y Λ N. N. Semenov Institute of Chemical Physics Russian Academy of Sciences Moscow, Russia y
More informationEffects of Variation of the Flame Area and Natural Damping on Primary Acoustic Instability of Downward Propagating Flames in a Tube
5 th ICDERS August 7, 015 Leeds, UK Effects of Variation of the Flame Area and Natural Damping on Primary Acoustic Instability of Downward Propagating Flames in a Tube Sung Hwan Yoon and Osamu Fujita Division
More informationTURBULENT FLOW ACROSS A ROTATING CYLINDER WITH SURFACE ROUGHNESS
HEFAT2014 10 th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics 14 16 July 2014 Orlando, Florida TURBULENT FLOW ACROSS A ROTATING CYLINDER WITH SURFACE ROUGHNESS Everts, M.,
More informationNear-wall Reynolds stress modelling for RANS and hybrid RANS/LES methods
Platzhalter für Bild, Bild auf Titelfolie hinter das Logo einsetzen Near-wall Reynolds stress modelling for RANS and hybrid RANS/LES methods Axel Probst (now at: C 2 A 2 S 2 E, DLR Göttingen) René Cécora,
More informationANALYSIS OF FLOW IN A CONCENTRIC ANNULUS USING FINITE ELEMENT METHOD
Nigerian Journal of Technology (NIJOTECH) Vol 35, No 2, April 2016, pp 344 348 Copyright Faculty of Engineering, University of Nigeria, Nsukka, Print ISSN: 0331-8443, Electronic ISSN: 2467-8821 wwwnijotechcom
More informationExplicit algebraic Reynolds stress models for boundary layer flows
1. Explicit algebraic models Two explicit algebraic models are here compared in order to assess their predictive capabilities in the simulation of boundary layer flow cases. The studied models are both
More information