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roughness length vs roughness height

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Old   November 2, 2020, 09:25
Default roughness length vs roughness height
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Sereff
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Hi All,

During my use of OpenFOAM, when ever I was to simulate a wall-bounded flow, I found it very hard to understand some of the terms used in wall-modeled boundary conditions, in particular, "roughness length" and "roughness height".

I understand that roughness height, often noted as z_0, which is the a fixed property of the system depending on the placement, shape, size of the roughness elements. And roughness height (K_s) on the other hand is a very loose concept. I read in a post on this furom, that it is around 20-30 times of z_0. Could anyone point me some more concrete material on how this term is defined?


Kind regards,
Sereff
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Old   March 15, 2021, 03:32
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Hi!I ran into the same problem,I suggest you read this artical: 《On the use of the k– model in commercial CFD software to model the neutral atmospheric boundary layer》
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