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-   -   Re: supersonic free jet nonphysical solution?? (http://www.cfd-online.com/Forums/phoenics/52304-re-supersonic-free-jet-nonphysical-solution.html)

Patti October 23, 2008 21:12

Re: supersonic free jet nonphysical solution??
 
I had a problem with the underexpanded free jet in the Case Library - I believe it's case 911. This gives the correct shock structure in 2-dimensions. When I change this into a three dimensional case (by adding circumferential grid points), and change all the objects (inlets, outlets, inits) to 3-D, it begins to experience very strong inflows at points next to the axis at the outlet. I tried: - dramatically increasing relaxations - decreasing the "snap" distance setting on the grid (maybe some of the points were degenerate?) - increasing the "coefficient" setting of the inlet

I don't know what else to try. I have occasionally experienced nonphysical behavior in cylindrical coordinates before and wonder if that's a hazard from the convergence of circumferential points near the axis, or if it's a problem with the solver? Thank You!!!!!!!!!!!!


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