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January 24, 2006, 14:40 |
Hi everybody,
I am a beginn
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#1 |
New Member
Magnus Åberg
Join Date: Mar 2009
Posts: 11
Rep Power: 17 |
Hi everybody,
I am a beginner OpenFOAM user with a wish of doing an investigation of the acoustics generated by a transonic jet through a nozzle. For this I tried rhoSonicFoam with initial conditions for the velocity field given by an incompressible solution of the same case. I then start the compressible case using a really low Courant number. After some 6000 iterations the calculation still looks good but then blows up very quickly. This is the case both when i use higher order vanLeer but also when I tried the upwind scheme. As I am a beginner user maybe this is not the right solver that I have choosen. Does anybody have ideas/suggestions of what I can do? Thanks for your kind answers! /Magnus |
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January 25, 2006, 04:20 |
It is usually something physic
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#2 |
Senior Member
Mattijs Janssens
Join Date: Mar 2009
Posts: 1,419
Rep Power: 26 |
It is usually something physical happening that causes this blowing up after such a long time of stable running. Check the solution just before it blows up. Maybe there is something happening (inflow?) at the outlet? Is the initial shock (from starting from an incompatible solution) reaching the outlet. Or is the solution finally going supersonic?
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January 25, 2006, 04:38 |
IC and BC should always be an
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#3 |
New Member
Shiuh-Hwa Shyu (Steven)
Join Date: Mar 2009
Location: Taiwan
Posts: 17
Rep Power: 17 |
IC and BC should always be an issue. A bad IC might eventially kills your calculation. But sometimes, the code might get survived and give you final solution. This would depend on the physical problem. As for BC, it would either give you a wrong solution, or just blow up. In my experience, the FDM tends to survive for quite a long period of time before it blows up, or gives you wrong solution. As for the spectral-like method, it would diverge quite quickly. This is a good thing though.
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January 25, 2006, 11:17 |
Many Thanks for your input!
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#4 |
New Member
Magnus Åberg
Join Date: Mar 2009
Posts: 11
Rep Power: 17 |
Many Thanks for your input!
I restarted my calculations, using first order schemes, with zero for pressure and velocity in the interior. I can see that the problem comes from the inlet patch I looked throught my boundary conditions and I found that maybe I misunderstand the meaning of pressureInletVelocity. What is the value i need to specify there? I want to specify totalpressure and totaltemperature what is the correct velocity BC for this setup? /Magnus |
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January 25, 2006, 11:19 |
Many Thanks for your input!
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#5 |
New Member
Magnus Åberg
Join Date: Mar 2009
Posts: 11
Rep Power: 17 |
Many Thanks for your input!
I restarted my calculations, using first order schemes, with zero for pressure and velocity in the interior. I can see that the problem comes from the inlet patch I looked throught my boundary conditions and I found that maybe I misunderstand the meaning of pressureInletVelocity. What is the value i need to specify there? I want to specify totalpressure and totaltemperature what is the correct velocity BC for this setup? /Magnus |
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February 1, 2006, 12:54 |
Hi,
I realize that what i w
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#6 |
New Member
Magnus Åberg
Join Date: Mar 2009
Posts: 11
Rep Power: 17 |
Hi,
I realize that what i wanted to do is not implemented. So I ask instead if somebody can give me a suggestion of which solver to use for a transonic turbulent jet with moving shocks. The inlet is subsonic and I whish to use LES for closure. Thank you /Magnus |
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February 1, 2006, 13:23 |
coodles with
"transonic true
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#7 |
Senior Member
Eugene de Villiers
Join Date: Mar 2009
Posts: 725
Rep Power: 21 |
coodles with
"transonic true;" added to the PISO subdictionary. No way it will capture shocks properly though. |
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February 11, 2006, 15:57 |
Could I modify sonicFoam (merg
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#8 |
New Member
Thomas Hauser
Join Date: Mar 2009
Posts: 1
Rep Power: 0 |
Could I modify sonicFoam (merge with coodles) to create a LES solver for compressible flow with shocks? Or are there better ways?
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June 14, 2006, 03:43 |
I have the same question as wh
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#9 |
Member
Dihao Tang
Join Date: Mar 2009
Posts: 78
Rep Power: 17 |
I have the same question as what Magnus asked:
"I want to specify totalpressure and totaltemperature what is the correct velocity BC for this setup?" I also use coodles, hope somebody can give me the answer, thanks! |
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