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how to deal with the surface roughness?

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Old   January 4, 2004, 10:41
Default how to deal with the surface roughness?
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maximus
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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.
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Old   January 5, 2004, 06:31
Default Re: how to deal with the surface roughness?
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Nicola
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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
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Old   January 5, 2004, 07:57
Default Re: how to deal with the surface roughness?
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maximus
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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.
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Old   January 7, 2004, 05:35
Default Re: how to deal with the surface roughness?
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Nicola
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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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