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Aerodynamic roughness length to equivalent sand-grain roughness?

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Old   July 12, 2019, 01:51
Default Aerodynamic roughness length to equivalent sand-grain roughness?
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Shannon Kieran
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Hi,

I am carrying out a Fluent simulation for a city block. In order to set the appropriate surface roughness for the wall boundary condition for the ground surface, I need to specify the sand-grain roughness height (Ks). However, because it is an atmospheric boundary layer problem, not a pipe system, the surface roughness parameters I do have are the aerodynamic roughness length (zo), and also approximate drag cofficient (Cd).

I've had a look at the theory guide, user guide and also various textbooks but haven't had any luck finding out how I can convert zo or Cd to an equivalent approximate Ks.

Any assistance would be appreciated!
(I am a university student)
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Old   July 12, 2019, 04:17
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Alexander
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you may try to find something here
https://www.sciencedirect.com/search...rtBy=relevance

best regards
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Old   August 19, 2019, 21:01
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Shannon Kieran
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Just thought I would post the following in case anyone has the same question later on.


I eventually found the answer to my question in this article:


Blocken B, Stathopoulos T, Carmeliet J. 2007. CFD simulation of the atmospheric boundary layer:– wall function problems. Atmospheric Environment 41(2): 238-252. Elsevier 2007.
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