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-   -   Why do some streamlines converge to one? (http://www.cfd-online.com/Forums/main/4956-why-do-some-streamlines-converge-one.html)

peter.zhao July 23, 2002 01:40

Why do some streamlines converge to one?
 
I am calculating a scramject combustor with seven species and eight-step H2-O2 reactions. The air with some H2O flows in the combustor, and H2 is injected from some injectors at wall at the normal direction to the wall. I use MUSCL TVD and LU-SGS to solve one temperature nonequilibrium chemical reaction N-S equations with B-L turbulence model.

After more than 10000 iterations under CFL number 0.5, the flow field seems OK. However, following the increasing iterations, the program diverges. Some streamlines converge to one, and sinks or sources appear in the flow field.

Can any one give me some suggestions?

All comments are warmly welcomed!

Thanks in advance!

soupy August 26, 2002 22:34

Re: Why do some streamlines converge to one?
 
It sounds like your solution is either diverging, or getting ready to. This may be related to your chemistry modeling... You might try turning all your chemical reactions off and see if your solution converges. And/or you might try decreasing your CFL and see if the same problem arises.

peter.zhao August 27, 2002 22:18

Re: Why do some streamlines converge to one?
 
Soupy,Thank you very much!! As you said, the solution diverges after some stream lines converge to one. However, if turn off chemical reaction, the solution behaves very well. I will check my program again.


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