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-   -   convergence problem (http://www.cfd-online.com/Forums/fluent/32440-convergence-problem.html)

 bylin November 4, 2003 10:57

convergence problem

I use standard k-epsilon model to compute confined jet, it just does not converge.Is this model fit for this problem?

 thomas November 5, 2003 11:07

Re: convergence problem

Hi, I am actually simulating a 'jet'. What solver are you using (VOF, Eulerian)? and could you describe a bit more what you have to model inpinging jet on a wall, jet injection into a water bulk ????? bye thomas

 David November 5, 2003 12:27

Re: convergence problem

have you tried to reduce the under relaxation factors?

pressure, momentum, kinectic energy, turbulence dissipation rate?

have you checked your boundary conditions?

lots of things to verify but please be more accurate in the description of your problem.

thanks

 bylin November 6, 2003 09:42

Re: convergence problem

Oh,thank you,thomas! It's an air round jet flowing into a coaxial surrounding air flow whose velocity is much less than that of the jet.And there is an annulus bluff body surrounding the outlet of the jet.

 bylin November 6, 2003 10:01

Re: convergence problem

Thank you,David.I'm a new comer for CFD,thanks for your advice. Reducing relaxation factors is of no use,and the solution seems to be insensitive to the boundary conditions.I suspect that the grid is not fine enough. So does refinement of the grid help?

 Volker Pawlik November 26, 2003 04:03

Re: convergence problem

See e.g. the user's guide: it is advised to use rke-model for round jets.

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