DynaflowC.F.D. conference

Transcription

1 DynaflowC.F.D. conference Lattce Boltzmann Smulatons and Applcaton to Multphase Flow Sacha Jelc, Senor C.F.D. Thermal Engneer Exa GmbH January 13th 2011

2 Agenda Company Overvew Current Applcatons Overvew Lattce Boltzmann Background PowerFLOW Smulaton Process Lattce-Boltzmann for Multphase Flow Multphase Applcatons Dscusson 2

3 Agenda Company Overvew Current Applcatons Overvew Lattce Boltzmann Background PowerFLOW Smulaton Process Lattce-Boltzmann for Multphase Flow Multphase Applcatons Dscusson 3

4 About the Company Developmentof Lattce-BoltzmannbasedCFD Technology Company founded n 1992 Based on research by founders at MIT Corporate Headquarters Burlngton, MA 180 employees (90+ PhD) Worldwde Support Centers USA: Boston, Detrot, San Francsco Europe: Stuttgart, Pars, Munch, London, Torno Asa: Tokyo, Seoul Current Sales Focus on Ground Transportaton 4

5 Automotve Customers 5

6 Aerospace/Defense Customers 6

7 Agenda Company Overvew Current Applcatons Overvew Lattce Boltzmann Background PowerFLOW Smulaton Process Lattce-Boltzmann for Multphase Flow Multphase Applcatons Dscusson 7

8 Man Automotve Applcatons Aerodynamcs Thermal Aeroacoustcs 8

9 Aerodynamcs 110% Drag Hstory Drag By Quadrants Drag Hstory (%CD) 105% 100% 95% Aero Baselne Tme-averaged Drag 90% Tme (sec) Aerospace Isosurfaces of Total Pressure Solng 9

10 Aeroacoustcs: Wnd Nose 10

11 Thermal Management Full 3D heat transfer analyss Underhood Surface Temperature Radaton, Convecton, Conducton Heat exchanger model for 2D coolant calculaton Radator Ar Recrculaton General Flow Structure Around Vehcle 11

12 Flud Structure nteracton Aeroelastc response of a hgh-aspect rato wng Hgh Lft teratvely 2-way coupled Results Publshed Flow 12

13 Agenda Company Overvew Current Applcatons Overvew Lattce Boltzmann Background PowerFLOW Smulaton Process Lattce-Boltzmann for Multphase Flow Multphase Applcatons Dscusson 13

14 Lattce Boltzmann Background Lattce gas automata (LGA): Hardy et al, Space dvded n cells, tme s dscrete. - Mcroscopc model for flud. - Mass and momentum conserved durng collson. t = 10 Collson Propagaton phase: 14

15 Lattce Boltzmann Background Lattce gas automata (LGA): Hardy et al, Space dvded n cells, tme s dscrete. - Dscrete mcroscopc model for flud. - Mass and momentum conserved durng collson. t = 21 Propagaton Collson phase: 15

16 Lattce Boltzmann Background Lattce Boltzmann equaton (LBE): McNamara and Zanett, Partcles are substtuted by partcle dstrbuton r r functons f ( t, x, e ), to reduce nose. r r r r f ( t + t, x + e t ) f ( t, x ) = Ω ( f ( t, x )) f r r ( t, x, e e r Ω ( f ) Advecton wth constant v Collson Operator ) Partcle dstrbuton functon Mcroscopc velocty Collson operator 16

17 17 (,, ) (,, ) t f x v t v f x v t + = Ω r r r r r Advecton wth constant v Collson Operator )), ( ( ), ( ), ( x t f x t f t e x t t f r r r r Ω = + + Contnues Boltzmann equaton Lattce Boltzmann equaton Lattce Boltzmann Background 0 = + α α ρ ρ x u t 0 ) ( = + + αβ β α β α ρ ρ D u u x t u Naver Stokes equatons

18 Lattce Boltzmann Background Collson operator: BGK approxmaton 1 (eq ) Ω = ( f τ f ) τ f (eq) Sngle relaxaton tme Soluton for unform gas, r r functon of ρ( t, x), u( t, x),... Lattce Boltzmann equaton: f f ( t r + t, x + r 1 ( t, x) ( f τ r e t) = r ( t, x) f ( eq) ( t, r x)) 18

19 19 Macroscopc quanttes Densty: Velocty Stress Tensor ), ( ), ( t x f x t r r = ρ β α αβ ρ β α u u x t f e e x t D = ), ( ), ( r r r r e t x f x t x t u r r r r r ), ( ), ( 1 ), ( = ρ Lattce Boltzmann Background

20 Lattce Boltzmann Background Assumng: c = t = x =1 Speed of Sound 1 c S = 3 c Pressure Vscosty p = υ = 1 c 3 c 2 ρ τ ( t ) Stablty: υ > 0 or τ > 1/ 2 20

21 Lattce Boltzmann Background Macroscopc conservaton equatons Mass: Momentum: Energy: ψ =1 0 ψ, ψ ( 1 2, ψ 3) 2 ψ = e r 4 = e r r r r r ψ [ f ( t + t, x + e t) f ( t, x) Ω ( f ( t, x))] = 0 Lattce Boltzmann equaton Mass: ρ + t ρu x α α = 0 Momentum: ρu t α + x β ( ρu u + D ) = α β αβ 0 21

22 Lattce Boltzmann Boundary Condtons Slp BC: No slp or bounce back BC: Perodc BC, nflow/outflow, Intal condtons. Wall model defnes turbulent flow propertes n 1 st cell centre. Cell-boundary ntersectons, curved surfaces [Fllpova and Hänel, 1998] 22

23 PowerFLOW External / Internal aerodynamcs DNS Heat transfer Porous meda Newtonan flud Instatonary Turbulence Modelng(RNG k-ε) Grd refnement wth VR-regons: 23

24 Postprocessng 24

25 WhyLattceBoltzmann? Hghest level of accuracy Inherently transent Low numercal dsspaton Ease of complex geometry handlng No smplfcatons necessary Guaranteed stablty Very fast turnaround tmes Days v. months Hgh scalabltyup to 1000 cores Exa s busness model: strong partnershps Jont valdaton& Methodology 25

26 Agenda Company Overvew Current Applcatons Overvew Lattce Boltzmann Background PowerFLOW Smulaton Process Lattce-Boltzmann for Multphase Flow Multphase Applcatons Dscusson 26

27 PowerFLOW5G Next generaton lattce Boltzmann solver Hgher order LB models Multphase Hgh Mach numbers. Current status Prototype has been completed Lookng for ndustral partners to gude further development 27

28 Multphase Lattce Boltzmann Key Prncple: Modelng Physcs not Phenomena Multphase s natural extenson of dscrete partcle approach Physcs of phase nteracton can be modeled more ntutvely Bothat theboundaryand n thebulkof theflud Key advantageovernaver-stokesbasedmethods: no requrement to track nterface front Interface fronts emerge from partcle nteractons 28

29 Multphase Lattce Boltzmann Multphase Model n PowerFLOW: Model nteracton force (Shan-Chen* Model) Model phase transtons through non deal gas sngle dstrbuton functon, van der Waals theory Enables very large densty ratos Any number of components can be modeled Each component s represented by st own dstrbuton functon σ r r σ σ r σ σ r f ( t + t, x + e t ) f ( t, x ) = Ω ( f ( t, x )) Interacton force between partcles and neghborng stes of dfferent speces 29 * Hudong Chen: Chef Scentst, Exa Corp. Xaowen Shan: Drector Advanced Physcs, Exa Corp.

30 Interacton modelng Defne nteracton force between molecules at x and x : Increment momentum n collson: ρ u = τf Macroscopc level: non-deal gas Equaton of State: 30

31 Capabltes & Lmtatons Capabltes Mult-phase Mult-component Phase transtons Cavtaton, condensaton, evaporaton,. Chemcal reactons Current lmtatons Low Reynolds number Heattransfer 31

32 Agenda Company Overvew Current Applcatons Overvew Lattce Boltzmann Background PowerFLOW Smulaton Process Lattce-Boltzmann for Multphase Flow Multphase Applcatons Dscusson 32

33 ApplcatonExamples Fuelcells Pumps Mult-phase Rotatng geometry Rock physcs Absolute & relatve permeabltes, capllary pressures Chemcal processng Separaton and fltraton Mxers Ppelne Flows Trbology Dropletflows. 33

34 Smulaton of water n gas dffuson layer Geometry: Scan of teflon-coated paper Smulaton condtons Frctonless sde walls and perodc nlet-outlet boundares condton The densty rato water/ar s order 1000 The Re number based on the porous structure heght and averaged termnal velocty of the water phase s 30 The Ca number s

35 Multphase ApplcatonExample: Dam Break Hgh Wettablty Low Wettablty 35

36 Dam Break: Comparsonto Experments Heght of leadng edge v. tme Locaton of leadng edge v. tme 36

37 Multphase ApplcatonExample: DropletBreakup Smulaton of water droplets n contnuous haxedecane phase Denstyrato~ 1 Knematc vscosty rato Experments show that generaton of daughter droplets can be controlled through passve breakup Depends on extenson and capllary number 37

38 DropletBreakup: Comparsonto Experment Smlar trend for splttng/no-splttng regons Crtcal Ca number s dfferent Maybedueto dfferencen denstyand dynamc vscosty ratos(knematc vscosty rato was matched) Contact angle: droplets n smulaton are non-wettng 38

39 Chemcal ReactonsApplcaton: Bosensors Applcaton: mcrodevce to screen drugs nhbtng AI-2 synthess Results shown n terms of Peclet and Damköhler nr. Hgh Pe: small converson of reactants, hgh overall flux of products Hgh Da: fast saturaton of converson of reactants Rght tradeoffpev. Da dependson applcaton Pe = 33 Pe =

40 Bosensor Converson of reactants as functon of Pe Converson of reactants as functon of Da Producton of new speces at the wall 40

41 Questons 41