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Old   March 10, 2012, 06:32
Default Problem with supersonic flow
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Bastian Schammann
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Hello together,

iŽve got a problem with the Fluent solver that don`t converg. IŽam simulating a radial turbine blade and want to show the pressure field with the shock waves.

I tried the following:

- different mesh to exclude that the error is caused by the mesh
- reduced courant number (0.1 ; 0.01 etc.)
- solution steering with supersonic flow in the "run calculation" settings
- velocity inlet instead of pressure far field in the boundary conditions
- w-cycle, v-cycle, F-cycle in the "advanced solution controls"

I always used the density based solver. Inviscid and energy equation is enabled.

Does anyone have an idea of how I can make the solver converge?

Kind regards
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Old   March 11, 2012, 12:51
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Does no one have an Idea?
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Old   March 12, 2012, 12:48
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What are the boundary conditions that you specify? How is your domain shaped?

Also, but this is just my curiosity, why have you chosen euler solver?

Rob
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Old   March 12, 2012, 12:59
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I used the euler equation after I have used the k-epsilon. I just wanted to simplifie the problem as a test because the solver didn't converge with turbulence model.

I mesh the geometrie with triangle or submap in Gambit.

Boundaries are:

INLET (pressure far field)
- Mach 1.9
- 140000 Pa absolute

OUTLET (pressure outlet)
- 20000 Pa absolut

After 3 days of try and fail I got greate improvements with the hybrid initialization (first I always tried standard initialization)
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Old   March 12, 2012, 14:02
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Why do you initialize the inlet as a pressure far field? I would try with pressure inlet.
Instead of using the hybrid initialization try to initialize the problem using fmg initialization (in the Fluent console you can find it under 'solve/initialize/FMG initialization').

Hope it helps,

Rob
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Old   March 12, 2012, 14:31
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Bastian Schammann
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Dear Rob,

thanks a lot for your reply. IŽll try out your suggestions.

Concerning pressure far field:

I found a tutorial in wich they used the pressure far field. So thatŽs why I used it too
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Old   March 12, 2012, 14:39
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Pretty curious, but it depends also on how is geometrically designed your domain.
Let me know if it works, normally FMG initialization solved many of my divergence problems.
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