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convergence criteria by lift and drag coefficent |
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March 17, 2011, 06:37 |
convergence criteria by lift and drag coefficent
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#1 |
New Member
Join Date: Feb 2011
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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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March 18, 2011, 07:44 |
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#2 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,854
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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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March 18, 2011, 07:50 |
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#3 |
New Member
Join Date: Feb 2011
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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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March 18, 2011, 15:38 |
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#4 |
Senior Member
Join Date: Mar 2009
Location: Europe
Posts: 169
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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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Tags |
cel expression, coefficient, convergence, drag, lift |
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