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-   -   one problem about stagnation boundary (http://www.cfd-online.com/Forums/cd-adapco/53372-one-problem-about-stagnation-boundary.html)

Lee July 3, 2003 05:00

one problem about stagnation boundary
 
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!

Lee

jing July 4, 2003 02:23

Re: one problem about stagnation boundary
 
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: http://www.adapco-online.com/feature_arts/ Paper name: compressible Flows. There are some way to solve the problem.

Good luck.



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