question for CFD developer's
 

Hello all,

why in such CFD code, they treat turbulence equation in different way that the Navier Stokes equations. for example the number of internal iterations for the Navier Stokes equations within a cycle is more bigger then the corresponding turbulent equations.
the CFD codes which have multigrid iterate Navier Stokes equations through the whole levels but they treat turbulence equation just in the finest level

best regards.

I don't really have a good answer, other than to say experience has shown that this approach is acceptable. Of course this decoupled approach is also easier to implement. However, I suspect that if a more coupled approach was taken the solution would converge faster. At least coupling it for an implicit solver. However, that is a challenging task.