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-   -   Compressor Simulation using rhoPimpleDyMFoam (https://www.cfd-online.com/Forums/openfoam-solving/143340-compressor-simulation-using-rhopimpledymfoam.html)

 vasava December 1, 2014 01:41

Quickly, if I were you I would not use fixedValue for inlet velocity if I am specifying pressure at the inlet. Instead use pressureInletOutletVelocity.

Also you are using fixed temperature at the outlet. Do you already know the temperature or you want openfoam to calculate the temperature? I would use fixed temperature at inlet and inletOutlet at outlet for temperature.

Please provide error messages, material properties and boundary files in the /0 folder.

 maHein December 2, 2014 02:58

I would specify total pressure and temperature at the inlet and static pressure at the outlet. Most of the time, defining a uniform velocity profile at the inlet is rather nonphysical.

You could use pressureInletOutletVelocity for the U at the boundarie.

 crixman December 2, 2014 09:39

thank you for the replies.
As you recommended, I specified the temperature at inlet and inletOutlet at outlet, and pressureInletVelocity for U at inlet.

If someone is interested, the same BCs do not converge on rhoSimpleFoam if I refine the mesh!

 maHein December 2, 2014 09:43

Have you tried lowering the relaxation factors when using the finer mesh?

 crixman December 3, 2014 07:04

Not really - I should check it, but I think it's more a SIMPLE algorithm problem than a matter of relaxation factors

 Tobi December 3, 2014 07:23

Quote:
 Originally Posted by crixman (Post 522275) Not really - I should check it, but I think it's more a SIMPLE algorithm problem than a matter of relaxation factors
Relaxation and SIMPLE is like a married couple (:
Without relaxation you will not can run SIMPLE in complex cases. This is due to some missing terms in the pressure prediction (see also Ferziger and Peric).

 crixman December 6, 2014 06:59

You are right - I meant it is possibly due to the fact that it is a very unsteady case and is probably not the best case to use SIMPLE - I am having good results with PIMPLE solvers so I'll stick to that for now

 crixman December 9, 2014 13:38

I am having AMI floating point exception problems when restarting the simulation from latestTime.
I got the same problem first when running renumberMesh in parallel after decomposePar - running rhoPimpleDyMFoam after decomposePar solved the problem.
Any ideas on how to solve this AMI issue at restart? Maybe someone had the same problem!

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