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-   -   pisoFoam, pimpleFoam - Fluent user's questions (http://www.cfd-online.com/Forums/openfoam-solving/123088-pisofoam-pimplefoam-fluent-users-questions.html)

RodriguezFatz September 4, 2013 04:26

pisoFoam, pimpleFoam - Fluent user's questions
 
Hi all,

Again I have some beginner's questions about the solver...
After mastering the steady-state simulation ;) I now want to run a time-dependent SAS simulation.
I am playing around with the two solvers pisoFoam and pimpleFoam.
1) I am not quite sure that I understood pisoFoam correctly, but what I think is, that it does not iterate the nonlinear terms, is that correct? So momentum equation is solved at the beginning, all other iterations are just used to solve for continuity equation?
2) When does that make sense? Time-steps have to be really small right? What about a bluff body / vortex simulation. Let's say, I have maybe 20-50 time steps per period. Do you think that is a case, where I can use pisoFoam?
3) For me it looks like that the solver pimpleFoam is, what Fluent calls "Piso", because outer iterations are introduced to pisoFoam, where the nonlinear terms are interated. Can somebody confirm that?

4) A somehow different topic: When I use "omegaWallFunction" as boundary condition in a fine y+=1 grid, the solver asks me to set an additional "value" anyway. But why? Is this just for initialization?

Thanks for any help,
Philipp.


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