How can I set wall roughness?
 

From Fluent User's Guide, I saw there's a possiblity to set wall roughness on the wall Boundary Condition panel. But I cannot find the roughness options in my wall panel. Could someone please tell me what the problem may be?

Thanks a lot.

Re: How can I set wall roughness?
 

This is possible only if you are using Turbulent model. Then average surface roughness can be specified. For laminar ( default ) model the roughness height can't be specified. Use Define->Models->Viscous-> k.e model, then if you try to apply bc on walls you would see the roughness height etc. Ashutosh

Re: How can I set wall roughness?
 

Thank you, Ashutosh. But I am using turbulent model (RNG K-e model), and can't find the roughness option in the wall bc panel. In the user's guide, there's a "optional" notation after the available wall roughness model. Does that mean some fluent version may not have this option? I really appreciate your help.

Re: How can I set wall roughness?
 

I am using Version 5.4.8, in which the wall panel shows the two factors for roughness, 1)Roughness height 2) Roughness constant. Earlier versions I don't have knowledge. What variables are you solving?

Ashutosh

Re: How can I set wall roughness?
 

I just checked that my version is also 5.4.8. I'm simulating how the air flow behaves when going through a narrow channel into a much larger chamber, and I plan to set roughness on the channel walls. I'm using RNG k-e model and check the velocity vectors of the flow.

Could you tell me the basic setup of your problem or BC's of which your wall panel shows the roughness options?

Thank you very much.

Ellen

Re: How can I set wall roughness?
 

(1). If you can't find it, then it is not there for that model.