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y+ vbalues in transient simulations

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Old   September 16, 2009, 11:25
Default y+ values in transient simulations
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Chris Turner
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Hi!

I am running a transient simulation that involves sending a pulse down a pipe and into a diffusing cone. The problem I am having is that the range of y+ values on the wall of the cone is between 5 and 450 throughout the simulation.

My computational facilities will not allow me to resolve the model to obtain y+ values of below 5 for all walls (this would put the model in excess of 5 million cells and currently at 400,000 it already takes days to solve).

Has anyone ever had this problem of a large range of y+ values? What can be done?

I was thinking pick the highest pressure seen in the pulse and run a steady state solution using that pressure as in inlet boundary, then resolving the mesh to obtain y+ between 30 and 300 for wall functions, almost like a worst case scenario. But then when a lower pressure is placed in the simulation, the low y+ values willl end up in the buffer region (5-30).

Sorry for the long post...

Thanks for any advice!

Chris

Last edited by chrisoturner; September 17, 2009 at 05:36. Reason: spelling errors
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