Learning Forum

[sachintom1992]

For transient flow boiling simulations (time step size ~ O(10^-4 s) using the Eulerian model which is the better choice for pressure velocity coupling? nIs the Phase coupled SIMPLE algorithm or Coupled algorithm?Regards,nJosephn

[Rahul Kumar]

Hello, nI would suggest the coupled solver. n

[sachintom1992]

Sir,n Any specific reason?n I have seen in forums for transient case simulations with small-time step size phase coupled SIMPLE is preferred whereas for steady state case and transient cases with large time step size only coupled solver is preferrable. Is it right?.Regards,nJosephn

[Amine Ben Hadj Ali]

All solvers should result, when converged, in the same results. That is the ideal! However each schemes might be prone to some issues.nFor long transients I usually prefer using SIMPLEC or PISO because they are cheaper than Coupled but the Coupled solver is usually the way to go: that is the solver which I apply with closed eyes. n

[Amine Ben Hadj Ali]

For multiphase the coupling is bit tough: for that reason I usually rely on Phase Coupled Simple in Fluent. In CFX I rely more on Fully Coupled: this is based on my experience with the solvers.n

[sachintom1992]

Sir,n Thanks for your reply.nCan you please clarify this?nI want to write a UDF for the interphase drag coefficient for the bubbly flow regime in ANSYS Fluent 2021 R1.n what is the actual term that has to go into the Fluent code for drag coefficient?nIs It Ai*Cd?nWhere Ai: Interfacial Area and Cd: Drag coefficientnRegards,nJosephn

[Amine Ben Hadj Ali]

It is Kpq.n