More than wall function

ivanwhlau · August 27, 2008, 05:36

Hello,

In my model, I need to have two different wall functions because two walls have significant different roughness. Is it possible?

Thanks,
iL

ngj · August 27, 2008, 07:57

Yes, it is definitely possible, as you just define the two boundaries with another type or different properties than those of the other boundaries.

If such a boundary condition is readily available in OF I do not know. It should be fairly straight forward. Try to look into the k-omega for rough surfaces posted in http://www.cfd-online.com/OpenFOAM_D...es/1/5791.html
but be careful I am advertising for my own work and it has not yet been tested/verified.

Best regards,

Niels

ivanwhlau · August 27, 2008, 12:36

Hi, Niels,

Thanks for your reply. I just looked at your thread.
However, I am actually looking for some simpler solution. Currently, there are variables "kappa and E" under wall function of k-epsilon models. I thought I can simply specify different E (small E for smooth surface and higher E for rough surface). I guess I need to modify the code to achieve this. Am I correct?

Best Regards,
iL

ngj · August 27, 2008, 13:43

I do not know, as I have not used in "build-in" wall function, and thus have not spent time looking into the source.

Best regards,

Niels

August 27, 2008, 05:36	Hello, In my model, I need	#1
ivanwhlau Member Ivan Lau Join Date: Mar 2009 Location: Hong Kong Posts: 56 Rep Power: 17	Hello, In my model, I need to have two different wall functions because two walls have significant different roughness. Is it possible? Thanks, iL

August 27, 2008, 07:57	Yes, it is definitely possible	#2
ngj Senior Member Niels Gjoel Jacobsen Join Date: Mar 2009 Location: Copenhagen, Denmark Posts: 1,900 Rep Power: 37	Yes, it is definitely possible, as you just define the two boundaries with another type or different properties than those of the other boundaries. If such a boundary condition is readily available in OF I do not know. It should be fairly straight forward. Try to look into the k-omega for rough surfaces posted in http://www.cfd-online.com/OpenFOAM_D...es/1/5791.html but be careful I am advertising for my own work and it has not yet been tested/verified. Best regards, Niels __________________ Please note that I do not use the Friend-feature, so do not be offended, if I do not accept a request.

August 27, 2008, 12:36	Hi, Niels, Thanks for your	#3
ivanwhlau Member Ivan Lau Join Date: Mar 2009 Location: Hong Kong Posts: 56 Rep Power: 17	Hi, Niels, Thanks for your reply. I just looked at your thread. However, I am actually looking for some simpler solution. Currently, there are variables "kappa and E" under wall function of k-epsilon models. I thought I can simply specify different E (small E for smooth surface and higher E for rough surface). I guess I need to modify the code to achieve this. Am I correct? Best Regards, iL

August 27, 2008, 13:43	I do not know, as I have not u	#4
ngj Senior Member Niels Gjoel Jacobsen Join Date: Mar 2009 Location: Copenhagen, Denmark Posts: 1,900 Rep Power: 37	I do not know, as I have not used in "build-in" wall function, and thus have not spent time looking into the source. Best regards, Niels __________________ Please note that I do not use the Friend-feature, so do not be offended, if I do not accept a request.

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