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 maximus January 4, 2004 10:41

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 log-law 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.

 Nicola January 5, 2004 06:31

Re: how to deal with the surface roughness?

K-omega model by Wilcox provides a simple method to include roughness effect by prescribing a Dirichlet-type 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, 1299-1310. Best regards,

Nicola

 maximus January 5, 2004 07:57

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, 1299-1310,????).And i wonder if it is diffcult to include the roughness effect in k-e model.Because I use the k-e model in my codes,I am trying to find a method to include the roughness effect in k-e model. thanks. maximus.

 Nicola January 7, 2004 05:35

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 k-e model is concerned, I can only tell you that in the case of the Star-CD 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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