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-   -   Transient 3D calulations (http://www.cfd-online.com/Forums/fluent/27499-transient-3d-calulations.html)

G. Berntsen February 17, 2000 05:18

Transient 3D calulations
 
Hi everyone.

I'm trying to do a cavitation calculation in a hydroturbine impeller using FLUENT5. This means that I have to use the transient solver. Test calculations, with the cavitation model activated, resulted in extremely unphysical results. This lead me to try the transient solver without the cavitation model invoked. This also resulted in strange solutions.

The way I have done this is by first calculating a steady-state solution (which seems to be a correct solution), and then starting the transient solver. The impeller movement is set up with the moving reference frame model.

Am I missing an option in FLUENT somewhere, or is it just impossible to do this kind of calculation?

Has anyone got any experience with this kind of problem? I would be very grateful for any recommandations concerning boundary conditions, discretization schemes, number of iterations pr. time step etc.

Thanks.

G. Berntsen.

Kuochen Tsai February 24, 2000 10:20

Re: Transient 3D calulations
 
Rotational reference frame is meaningful for steady-state solutions.

Jonas Larsson February 24, 2000 10:41

Re: Transient 3D calulations
 
Eh, it is also meaningful for transient simulations... Rotating cavities is a typical example.

Kuochen Tsai February 24, 2000 10:47

Re: Transient 3D calulations
 
Yes, for rotating cavity it is OK, but not for impellers or solid boundaries with relative boundary movment.


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