Mr Yeru Shang - PDF document

1 Ctt Contact: MYSh Mr Yeru Shang g P
Ctt Contact: MYSh Mr Yeru Shang g PhDStudentandAssociateTutor ThEtfSGSMdlthLEdd PhD Student and Associate Tutor TheEectofSGSModelsontheLargeEddy Thermo FluidMechanics ect of SGS Models on the Large Eddy Thermo Fluid Mechanics gy ResearchCentre(TFMRC) Research Centre (TFMRC) onofaCorrugatedChannelFlow UiitfS onofaCorrugatedChannelFlow University of Sussex on of a Corrugated Channel Flow yf +44(0)1273876706 +44 (0) 1273 876 706 Yerushang@sussexacuk Yeru.shang@sussex.ac.uk GOAL: MOTIVATION: GOAL: MOTIVATION: AnalysetheeectofdierentSub gridScale(SGS)modelsontheLarge Theexisngresearchesinacademiaonmulplecaviesorcorrugated Analyse the eect of dierent Sub grid Scale (SGS) models on the Large The exisng researches in academia on mulple cavies or corrugated y g()g EddSil(LES)fhlidhl llfiilid/idlidAlhh EddySimulaon(LES)oftherealisccorrugatedchannel wallarefocusingonsimplied/idealisedgeometryAlthoughreports Eddy Simulaon (LES) of the realisc corrugated channel ow. wall are focusing on simplied/idealised geometry. Although reports showmanySGSmodelsperformwellontheseidealisedgeometries show many SGS models perform well on these idealised geometries, ypg, hifdi theiraccuracyofpredicononmorerealisccorrugatedgeometryhas Realis Academia their accuracy of predicon on more realisc corrugated geometry has Realis Academia notbeensystemacallyevaluated not been systemacally evaluated. yy h CurrentResearch Current Research CASEINTRODUCTION: CASE INTRODUCTION: Thegeometryisa2Drepresentaonofawidelyusedcommercialstain The geometry is a 2D representaon of a widely used commercial stain lesssteelexpipe(heatexchanger)withacircularcross onthe less steel ex pipe (heat exchanger) with a circular cross secon. the pp(g) omwallhasawavyshapewithperiodicgrooveswhereastopwall om wall has a wavy shape with periodic grooves, whereas top wall andtwosidewallsarebothatplates and two sidewalls are both at plates. p NUMERICALSETUPS NUMERICAL SETUPS: PeriodicBoundaryCondion(BC)isappliedtobothinletandoutletSpaalinterpolaonofconveconanddiusionterms is basedon2ndordercen Periodic Boundary Condion (BC) is applied to both inlet and outlet. Spaal interpolaon of convecusion terms is based on 2nd order cen y()pppp traldierencingschemeTimemarchingisapproximatedby2ndorderbackwardsdi fv elocityandpres tral dierencing scheme. Time marching is approximated by 2nd order backwards dierencing implicit scheme. The decoupling o f v elocity and pres ibidbPISOlihililldbdi( i hl sureintheequaonisobtainedbyPISOalgorithmievelocitycomponentsarecalculatedbyonemomentumpredictorstep(u sin gsmoothsolvers sure in the equaon is obtained by PISO algorithm, i.e. velocity components are calculated by one momentum predictor step (u sin g smooth solvers withsymmetricGauss Seidelsmoother)andpressureeldiscorrectedtwice(bygeneralisedgeometric algebraicmul grid(GAMG )solver)with with symmetric Gauss Seidel smoother) and pressure eld is corrected twice (by generalised geometric algebraic mul grid (GAMG ) solver) with y )p(ygg g g( )) Gauss Seidelsmootherfortherstcorrectorstepanddiagonalincomplete Cholesky/LUwithGauss Seidel(DICGaussSeidel)forth esecondone Gauss Seidel smoother for the rst corrector step and diagonal incomplete Cholesky/LU with Gauss Seidel (DICGaussSeidel) for th e second one. MESHDETAILS: CALCULATIONPROCEDURE: MESH DETAILS: CALCULATION PROCEDURE: ThttdhhdlhidittdThhdit Aflldldldith The structured hexahedral mesh is used in current study. The mesh density A fully developed yy yp increasesasapproachingthewallTherstlayerdistanceonthecorrugated SMAG+VDisusedasinialcondionforall increases as approaching the wall. The rst layer distance on the corrugated SMAG+VD is used as inial condion for all llilh0005llilh0006did ihhSGSdlAll wallislessthan0005mmontopwallislessthan0006mmandonside caseswithotherSGSmodelsAllcasesare wall is less than 0.005 mm, on top wall is less than 0.006 mm and on side cases with other SGS models. All cases are wallsislessthan006mmAposterioranalysisshowsthaty+valueforthe allowedforafurther1ssimulaontoen walls is less than 0.06 mm. A posterior analysis shows that y+ value for the allowed for a further 1s simulaon to en pyy corrugatedwallislessthan025withameanvalueof004fortopwallitis suretheoninducedbythechange corrugated wall is less than 0.25 with a mean value of 0.04, for top wall it is sure the on induced by the change lh016ihlf011fidlliilh24ih fSGSdlbldflldb lessthan016withameanvalueof011forsidewallsitislessthan24with ofSGSmodeltobeseledfollowedbyan less than 0.16 with a mean value of 0.11, for sidewalls it is less than 2.4 with of SGS model to be seled, followed by an ameanvalueof072jusfyingtheuseofno slipwallboundarycondi averagingwindowof8sFloweldbecame a mean value of 0.72, jusfying the use of no slip wall boundary condi averaging window of 8s. Flow eld became ,jyg py gg Thetotalnumberofmeshcellsforeachcorrugaonis09million callysteadybeforedataprocessing The total number of mesh cells for each corruga cally steady before data processing. RESULTSANDFUTURESTUDIES RESULTSANDFUTURESTUDIES: RESULTS AND FUTURE STUDIES: (c) AllSGSdlttdithttddith (c) AllSGSmodelstestedinthecurrentstudycanpredictacha All SGS models tested in the current study can predict a cha o dimensionalandunstableeld(Figa)Vortex c, 3 dimensional and unstable eld (Fig. a). Vortex , (g) Evoluonandhydrodynamicsobservedintheexperiment Evoluon and hydrodynamics observed in the experiment (f) bddbllSGSdliLES(Fib)Thit (f) canbereproducedbyallSGSmodelsinLES(Fig.b).Thesuit () can be reproduced by all SGS models in LES (Fig. b). The suit a b l e c h a n n e l l e n g t h i s 1 6 c o r r u g a o n s ( F i g c ) a n d t h e c u r r e n t a b l e c h a n n e l l e n g t h i 1 6 c o r r u g a o n s ( F i g . c ) a n d t h e c u r r e n t g g ( g ) gridisadequatelyne(Figd)Theresultssuggestthatthe grid is adequately ne (Fig. d). The results suggest that the iiitthltdSGSdlfbth onisinsensivetotheselectedSGSmodelsforboth (d) on is insensive to the selected SGS models for both (d) meanvelocityprole(Fige)andturbulenceintensity(Figf () mean velocity prole (Fig. e) and turbulence intensity (Fig. f yp(g)y(g h)dlblllbd h)InnextstagedierentinletturbulenceBCswillbetested h). In next stage, dierent inlet turbulence BCs will be tested. (g) (g) (a) (a) () (e) (e) () (b) (b) (b) (h) (h)