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Old   March 10, 2013, 23:10
Default meshing in flow separation region
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Joseph Neil
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can anyone help me in my turbulent flow problem with sudden expansion pipe. i am using k-e model with standard wall function in fluent. i ve meshed the geometry in gambit and i didnt get t y+ values along the wall above 12.

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Old   March 11, 2013, 17:14
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Lefteris
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Maybe you could use the Enhanced Wall Treatment.


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Originally Posted by ajneil View Post
can anyone help me in my turbulent flow problem with sudden expansion pipe. i am using k-e model with standard wall function in fluent. i ve meshed the geometry in gambit and i didnt get t y+ values along the wall above 12.

regards
jose
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Old   March 14, 2013, 12:58
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Joseph Neil
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1) can u explain how enhanced wall treatment gives better results?
2) is it very herd to mesh in the flow separation region?
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Old   March 14, 2013, 14:19
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Using standard wall functions means that you ignore the viscous sublayer and that's why you need a y+ >30 (you may want to take a look here: http://www.cfd-online.com/Wiki/Law_of_the_wall).
If y+ is lower than that, Fluent offers the choice to use the enhanced wall treatment whose details you can read here: http://cdlab2.fluid.tuwien.ac.at/LEH...ug/node514.htm

To mesh the flow separation region you need to have some indication as to where this region is. This can be deduced from experimental data or from a simulation on a coarse grid which you refine at the separation region.
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