[Shanny]

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)

[AlexanderZ]

you may try to find something here
https://www.sciencedirect.com/search...rtBy=relevance

best regards

[Shanny]

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.

[mimarilker]

I have read this article for numerous times, but it does not offer an exact solution. Could you please share how you solved your problem?

[mz_uon]

This paper offers a direct solution to equivalent sand grain height, as is needed to be input in Fluent for ABL simulation

http://www.cobee2018.net/assets/pdf/p/063.pdf

[MoaMD]

Originally Posted by mz_uon

This paper offers a direct solution to equivalent sand grain height, as is needed to be input in Fluent for ABL simulation

http://www.cobee2018.net/assets/pdf/p/063.pdf

the link is broken, could you please provide the title of the paper? thanks in advance