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Old   July 14, 2011, 16:53
Question Turbulence boundary conditions
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Ammar Tareen
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Hello World,

I created a half laval nozzle geometry and run air through it from one side to the other. Initially I ran a laminar simulation and found out that results tend to get quite turbulent. I'm now at the stage where I want to implement the k-epsilon model for turbulence.

The trouble I'm having is that when I run the simulation I start to get nonsensical velocity, pressure and temperature profiles e.g. I start getting negative pressures and velocities as high has 10^24 m/s. This is because I don't understand the K-epsilon boundary conditions well enough.

I am attaching my case file, can anybody give me any pointers as to how I should change the boundary conditions file to get reasonable results? The files P,T,U are ok, it's the rest of them that I don't understand. It's quite possible that I put the wrong bc's.
I should point out that in the laminar case, I specify high pressure at the inlet and lower pressure at the velocity, and that's how flow develops.

I am also attaching a picture of the results from the laminar simulation just so you know what the profiles look like. Any help would be greatly appreciated.

Regards,
Ammar.
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File Type: zip testTurb.zip (37.2 KB, 10 views)
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Old   July 16, 2011, 03:43
Default k-epsilon bc settings
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Namsu
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Hi
I am working on the impinging jets and also facing the same problem that I donít really know how to set the k-epsilon boundary conditions, how to calculate the k, omega, epsilon, kqwallfunction, omegawallfunction, nutwallfuction. I appreciate if somebody gives a detailed answer so that a basic understanding would be developed.
Regards.
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Old   July 17, 2013, 08:02
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Marcus
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Hello,

i simulate with k-omega sst Modell, but this also interests me and that is why i've found some files for this.
Here are the files compressed...maybe it helps you.
For this topic, you must only write this in your browser to find the master thesis:

www.tfd.chalmers.se/~hani/pdf.../AISwithOF.pdf‎

I hope it helps...
best regards

Marcus
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