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convergence criteria by lift and drag coefficent

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Old   March 17, 2011, 06:37
Default convergence criteria by lift and drag coefficent
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Hello,

I have modelled a flow over an airfoil in cfx which works fine so far. Futhermore i have created monitorpoints for lift- and drag-coefficent.
What i want to do now is to set a interrupt control condition in cfx pre so that the actual value of the coefficent is compared to the one ten iterations before. If the difference is under a defined limit (let's say 0.1%) the simulation should be stoped.
My problem is that I don't know the CEL-Syntax to get a value at a certain iteration.

Maybe somebody knows how to program that.

Thanks
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Old   March 18, 2011, 07:44
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This cannot be done easily in CEL.

You will probably find a residual convergence tolerance to correspond to your coefficient convergence. Then you could just use a simple residual convergence tolerance.

If you insist on using your coefficients to judge convergence then I would have a cron job running in the background (ie outside of CFX) which monitors the monitor point output files and when it senses convergence it runs the cfx5stop command.
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Old   March 18, 2011, 07:50
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Thanks for the reply. I think I'll go with the normal residuals so far. I had a phoncall with the CFX-Support yesterday and they told me the same. Maybe when I have more time I'll try to pragramm some tool to monitor the coeffiecents and stop the solver run.
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Old   March 18, 2011, 15:38
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The service send me an user fortran example, which stores older values, some time ago. I am not permitted to distribute further, however you may get it if you ask.
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