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How much does a skewed element effect a solution ?

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Old   April 5, 2002, 09:44
Default How much does a skewed element effect a solution ?
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joseph
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HI

How much does a skewed hexahedral element effect a solution in CFX 5.5 ?(structured grid),especially in a MFR problem

what is the least angle recomended by CFX 5.5. from 0-90 deg?

thanks

joseph
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Old   April 5, 2002, 23:43
Default Re: How much does a skewed element effect a soluti
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Neale
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CFX-5 can handle fairly bad skew angles, say >10-20 deg. The quality of the solution is going to rely mainly on how many you have. If 50% of your elements are skewed, then your going to have a tough time, and you will probably get a bad answer. If 5% are skewed, then you might be OK.

Neale
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Old   April 7, 2002, 17:10
Default Re: How much does a skewed element effect a soluti
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steve
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It depends a lot on where the cells are, i.e. in the far-field where the flow is roughly constant the solver will have little problem with highly skewed cells. However in the boundary layer or in the vicinity of a shock you should have orthogonal cells.

The best way to check if skewed cells are degrading the solution is to perform a grid convergence test - i.e. double the grid resolution and see if the results change. You should also plot the residuals in post and see if the largest residuals are in the highly skewed cells.
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Old   April 8, 2002, 00:21
Default thank you steve and Neale
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joseph
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hi,

thanks for your valuable comments.

Joseph
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