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one problem about stagnation boundary

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Old   July 3, 2003, 05:00
Default one problem about stagnation boundary
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I created a round pipe model,the inflow boundary I set the stagnation boundary,and the other outflow boundary I gave a pressure boundary,because the mode is a axisymmetry model,so I just simulate one quarter of it,then I have set another symmetry boundary at the symmetric planes. The stagnation pressure was set to vary with the time,but when I run the model,star-cd often gave a warning message: " *** WARNING #061 *** RATIO OF STAGNATION PRESSURE AND STATIC PRESSURE AT REGION 1 CELL xxx LESS THEN 1. TEMPORARILY SET TO 1."

And I checked the results I found it was wrong,so I think maybe it is caused by the stagnation boundary,but I must set the inflow boundary as a stagnation boundary,so whether are there guides to help me out this problem? What is the reason to cause the problem?

Your help is great appreciated!

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Old   July 4, 2003, 02:23
Default Re: one problem about stagnation boundary
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It is because that stagnation pressure is not a variable in equaitons in StarCD. The solver solves pressure directly, and deduce the stagnation pressure based on corrected velocity. If the initial flow field is not in on a right way, the stagnation pressure will be smaller that the static pressure. This is what the error message means.

Please check the paper: Paper name: compressible Flows. There are some way to solve the problem.

Good luck.

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