segragated solver vs couple solver

Ana Herrero · September 21, 2020, 14:34

Hi!
quick question. Should I expect different results if I run one same geometry with segregated solver and couple solver?? So the only difference between both run would be the solver (turbulence model, mesh, etc the same for both cases), and of course, assuming that both cases converge.
Why is the coupled solver recommended for external aero cases, even if it is an incompressible simulation??
Thank you very much in advance!!

sbaffini · September 22, 2020, 07:51

It depends, coupled solvers typically need different convection schemes. And even for equal schemes the coupling plays a relevant role.

So, in general, you can only expect similar results within the respective accuracies (equal to the naked eye). But as the equations are non linear, you can't exclude that, in certain cases, some effects of one solver will drive the solution away from the other.

September 21, 2020, 14:34	segragated solver vs couple solver	#1
Ana Herrero New Member Ana Join Date: Sep 2020 Posts: 10 Rep Power: 5	Hi! quick question. Should I expect different results if I run one same geometry with segregated solver and couple solver?? So the only difference between both run would be the solver (turbulence model, mesh, etc the same for both cases), and of course, assuming that both cases converge. Why is the coupled solver recommended for external aero cases, even if it is an incompressible simulation?? Thank you very much in advance!!

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September 22, 2020, 07:51		#2
sbaffini Senior Member Paolo Lampitella Join Date: Mar 2009 Location: Italy Posts: 2,151 Blog Entries: 29 Rep Power: 39	It depends, coupled solvers typically need different convection schemes. And even for equal schemes the coupling plays a relevant role. So, in general, you can only expect similar results within the respective accuracies (equal to the naked eye). But as the equations are non linear, you can't exclude that, in certain cases, some effects of one solver will drive the solution away from the other.