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Fluid/Structure Coupling (FSI)

For the flu­id struc­ture in­ter­ac­tion, a loose­ly cou­pling method is used. For the flu­id part, the CE/­SE method is used based on Euler­ian frame and the struc­ture  is treat­ed as an em­bed­ded mov­ing bound­ary, while in the struc­ture, a FEM solver is em­ployed based on La­grangian frame. Both flu­id and struc­ture mesh­es are in­de­pen­dent (more ac­cu­rate if the flu­id mesh size is small­er than the struc­tur­al mesh size).

The in­ter­face bound­ary lo­ca­tions and ve­loc­i­ties are dic­tat­ed by the La­grangian struc­ture. That in­for­ma­tion will be used by the flu­id solver as the in­ter­face con­di­tions at each time step, and it will feed back the flu­id pres­sures (forces) on the struc­tur­al in­ter­face as ex­te­ri­or forces for the struc­ture solver.

In the fu­ture, when the au­to­mat­ic vol­ume mesh­er op­tion was im­ple­ment­ed, all FSI bound­aries will be La­grangian and de­form with the struc­ture al­low­ing ex­act im­po­si­tion of bound­ary con­di­tions.