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Old   November 18, 2008, 18:37
Default under relaxation for natural convection
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For natural convection, what are the best practices to set under relaxation parameters? Thanks.
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Old   November 19, 2008, 07:33
Default Re: under relaxation for natural convection
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Hello Jimmy,

In my experience natural convection and mixed convection problems can be hard to converge. Tricks that you can try are:

- reduce the relaxation parameters. (generally never to less than about 20% of the standard setting)

- get a first order upwind solution before switching to second order accuracy.

- Use time steps instead of a steady state solution to get an approximate answer, then possibly return to steady state.

Also be aware of the fact that standard wall functions are not developed to be used in natural convection cases. the options you have here depend on which program you are using. (in case of enhanced wall treatment, check your grid!)

Regards, Wiebe.
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Old   November 19, 2008, 20:30
Default thanks much *NM*
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