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-   -   How much does a skewed element effect a solution ? (http://www.cfd-online.com/Forums/cfx/18910-how-much-does-skewed-element-effect-solution.html)

joseph April 5, 2002 09:44

How much does a skewed element effect a solution ?
 
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

Neale April 5, 2002 23:43

Re: How much does a skewed element effect a soluti
 
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

steve April 7, 2002 17:10

Re: How much does a skewed element effect a soluti
 
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.

joseph April 8, 2002 00:21

thank you steve and Neale
 
hi,

thanks for your valuable comments.

Joseph


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