Roughness height
I am working on tube flow with L = 1000 mm, D = 19 mm and tube thickness = 0.5 mm. I am using SST k-w model.
Now I want to use Wall Roughness case. There are two input needed. These are 1. Roughness height 2. Roughness constant. I set Roughness constant = 0.5. It means uniform roughness along the tube. But what is called Roughness height? How to calculate this? Any suggestions pls? |
Did you already consult the manual?
The description of the wall-roughness model is quite complete. The roughness height is the equivalent sand-grain roughness. There are formulas relating this parameter to roughness units used in engineering nowadays. |
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Now I want to know, what's the relation between relative roughness and roughness height? How to setup this in Fluent? I am really confused. Thanks |
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I am not validating Fluent roughness model. What I want to know first, what is the correct input of roughness height in fluent? Then I will validate the moody chart to make sure that I am heading towards right way and then I will apply this model for another application. |
This is my view. But honestly I cant think of any other way to interpret this equation with only 3 variables.
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I believe, I am not the first one who is doing work on rough surface for tube. I am really interested to know, how other user of fluent handling this problem. Many thanks for your time. I will let you know the outcomes. Thanks |
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Thanks |
fluent manual: 7.3.14 Wall Boundary Conditions the Roughness Height, Ks in fluent boundary conditions: Roughness Height (m) so this has to be the same as the Ks in the sand-grain roughness Table. for copper, it has to be 0.0000015 m |
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