|February 24, 2012, 15:45||
Join Date: Feb 2012
Posts: 6Rep Power: 6
I am trying to get a better understanding of what the "Wall Roughness" box is (in the wall boundary layer box) referring to.
Is this the height found on standard charts? (see http://www.engineeringtoolbox.com/su...cts-d_209.html).
i.e. If I was to use Stainless Steel than the Roughness Height would be k=5E-5ft.
Is the roughness constant the number calculated (relative roughness).
i.e. Using the hydraulic diameter (d=23.5in), and k. Equation is r=k/d == having a value of 26E-6.
Can someone please help?
|February 24, 2012, 15:57||
Join Date: Oct 2010
Posts: 993Rep Power: 17
You are right for the roughness height, but roughness constant isn't relative roughness: fluent uses this parameter to specify uniformity of roughness: since there is no indication on how to calculate it, you have to try and see if your simulation results approximate your experimental results; roughness constant=0,5 indicates a uniformal roughness; use values between 0,5 and 1 to specify non uniformal roughness.
Last edited by ghost82; February 25, 2012 at 03:44.
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