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Any idea on how to obtain Yplus value for interior cells?

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Old   April 11, 2012, 02:00
Default Any idea on how to obtain Yplus value for interior cells?
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Joshua
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Although C_Wall_Dist can calculate the distance between a cell and the nearest wall, we could not identify this wall and thus can not get the wall shear stress, which is required for the calculation of Yplus.

I have searched, through the entire google, for this problem without a solution. Do you have any idea to share with us?

Regards,
Joshua Zhu
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Old   August 18, 2013, 09:18
Default calculation of y+ for interior points?
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Quote:
Originally Posted by g0800276 View Post
Although C_Wall_Dist can calculate the distance between a cell and the nearest wall, we could not identify this wall and thus can not get the wall shear stress, which is required for the calculation of Yplus.

I have searched, through the entire google, for this problem without a solution. Do you have any idea to share with us?

Regards,
Joshua Zhu
Quote:
Originally Posted by om3ro View Post
I'm trying to implement the Chien model with OpenFoam, but I have some general doubts on the description of y+.

The Chien model uses y+ for the definition of the damping factors.

Suppose to describe a 2D duct flow in with the following configuration:

HTML Code:
<pre>

     /\  y
      |
      |
      |
      ------------>  x

____________________________________________
->                                                                    ->
->                                                                    ->
->                                                     *             ->
->_________            _ ,       .________,*________->
                  |         |  |         |                
                  |____ _|  |___ __|


</pre>
y+ is defined as: y+ = (U_t * y) / nu

and U_t(x) = sqrt(tau_w(x) / rho)

y+, U_t, tau_w are functions of x!!!

It is necessary to define for each point (x,y) of the numerical domain the x coordinate in which define y+, U_t and tau_w.

An example:

In both points identified with " * ", tau_w must be evaluated in " , ".
But in the point " ", shall tau_w be associated with " , " or with " . " ?

Does anybody have experience on this aspect? What is the principle to adopt in this task?

Marco

Hi,
The Chien model uses y+ for the definition of the damping functions.
Does anybody have knowledge about calculation of y+ for interior points?

Best Regards,
AtiCFD
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