how to deal with the surface roughness?
I have to consider the roughness effect on heat transfer in the flow near the rough wall.and I find the traditional method is to use the boundary layer integration which can include the roughess effect by using the roughness Renolds number.Another method is to modify the loglaw of velocity near the wall.here my question is if there is a turbulence model or a wall funtion which can include the roughness effect. thanks.

Re: how to deal with the surface roughness?
Komega model by Wilcox provides a simple method to include roughness effect by prescribing a Dirichlettype boundary condition at wall for omega. For the details, see the Chima's report at www.grc.nasa.gov/WWW/5810/webpage/docs/kw6.pdf. You can also refer to the paper of Wilcox himself: Reassessment of the scale determining equation for advanced turbulence models, AIAA Journal, 26, 12991310. Best regards,
Nicola 
Re: how to deal with the surface roughness?
hi,Nicola,I am very appreciate for your advice.I've got the first paper you told me,but Can you tell me the exact year of the second paper in AIAA Journal(AIAA Journal, 26, 12991310,????).And i wonder if it is diffcult to include the roughness effect in ke model.Because I use the ke model in my codes,I am trying to find a method to include the roughness effect in ke model. thanks. maximus.

Re: how to deal with the surface roughness?
Maximus, I'm sorry for the late answer. The exact reference is Vol. 26 No. 11 November 1988. As far as the ke model is concerned, I can only tell you that in the case of the StarCD code, roughness effects are taken into account by wall functions, but I don't know if there is some other method. I suggest you a careful search using google. Best regards,
Nicola 
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