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heat transfer probs by transonic flow

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Old   March 19, 2010, 14:05
Default heat transfer probs by transonic flow
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Hi all,

I am simulating the heat transfer between a sphere and its environment by subsonic and supersonic incident flow in 2D. Furthermore the flow shall be compressible.

Here some key data:
- sphere BC: wall, no slip and constant temperature
- inlet BC: pressure far field
- outlet BC: pressure outlet
- density based solver steady state

Now, I'm dealing some problems by simulating the transonic flow (0.8<M<1.4). Despite of good convergence (except of M=1.3 and M=1.4) the contour plot of velocity magnitude is really strange. The other ranges like 0.4<M<0.8 and M>1.4 meet my expectations both in convergence and contour plots.

So what am I doing wrong? Should I maybe run the simulation now unsteady or do I have to take sth. else into account??

Any suggestions and answers are welcome! Thanks in advance!! :-)
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Old   March 19, 2010, 14:29
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Turbulence?
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Old   March 20, 2010, 07:01
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oh sorry, I forgot to mention: No, it's laminar...
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Old   March 20, 2010, 09:22
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Quote:
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oh sorry, I forgot to mention: No, it's laminar...
I'm no expert, but can a transsonic flow be laminar?
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Old   March 20, 2010, 16:57
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why not? I am not an expert as well, but I was thinking that there is no problem running a transonic and laminar simulation...
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Old   March 20, 2010, 17:43
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Quote:
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why not? I am not an expert as well, but I was thinking that there is no problem running a transonic and laminar simulation...
Depends on your Reynolds number. Can you tell us what it is?
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Old   March 20, 2010, 18:11
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well, since the sphere has a diameter of 5µm, the Reynolds number is definitly below 100 (in between of 60 and 80)..
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Old   March 21, 2010, 04:24
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Ok, this is laminar. I have no further ideas, what may be wrong.
And your solution is good in medium and high Mach numbers?
Strange ...
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Old   March 21, 2010, 06:31
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right, low and high Mach numbers are ok, but the transonic range... :-/
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