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Old   August 18, 2009, 05:33
Default Y+ problem
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pipin
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Hello,

I've a problem with my mesh, i have Y+ > 1000 in a nozzle.
With the non equilibrium law (30<Y+<300) what do you think about the wall treatment in this condition?
thanks for reply
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Old   August 19, 2009, 23:34
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Sean Delfel
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Hi Pipin,

I believe you should refine your mesh in the areas with y+ over 300 -- the turbulence model assumes a "shape" of the velocity profile below the first grid point, which is why it is important to get it in the right location. My suggestion would be to check the y+ value using contours -> turbulence -> wall y+ in fluent and then refine your grid in gambit (or whichever preprocessor you're using). You can also use the adaption tools in fluent, but I generally don't like the changes they make and end up with convergence problems. That could be because I'm not using them properly, though.

Cheers,
-sean
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Old   August 20, 2009, 16:10
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U must refine mesh at wall as your turbulence model.
It is very inportant, because viscousity calculation near wall seriously depends on wall grid condition.
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Old   August 20, 2009, 20:59
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feng
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you can also use the near-wall model in fluent if you want to get the accurate representation of the flow in the near-wall region.
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