Dynamicfluid-solidinteractionsarewidelyfoundinchemicalengineering,suchasinparticle-ladenflows,whichusuallycontaincomplexmovingboundaries.Theimmersedboundarymethod(IBM)isaconvenientapproachtohandlefluid-solidinteractionswithcomplexgeometries.Inthiswork,Uhlmann’sdirect-forcingIBMisimprovedandimplementedonasupercomputerwithCPU-GPUhybridarchitecture.Thedirect-forcingIBMismodifiedasfollows:thePoisson’sequationforpressureissolvedbeforeevaluationofthebodyforce,andtheforceisonlydistributedtotheCartesiangridsinsidetheimmersedboundary.Amultidirectforcingschemeisusedtoevaluatethebodyforce.Thesemodificationsresultinapergence-freeflowfieldinthefluiddomainandtheno-slipboundaryconditionattheimmersedboundarysimultaneously.Thismethodisimplementedinanexplicitfinite-differencefractional-stepscheme,andvalidatedby2Dsimulationsoflid-drivencavityflow,Couetteflowbetweentwoconcentriccylindersandflowoveracircularcylinder.Finally,themethodisusedtosimulatethesedimentationoftwocircularparticlesinachannel.Theresultsagreeverywellwithpreviousexperimentalandnumericaldata,andaremoreaccuratethantheconventionaldirect-forcingmethod,especiallyinthevicinityofamovingboundary.
