Smagorinsky coefficient average on planes parallel to walls

huangxianbei · June 12, 2014, 10:33

Hi,all:
In channel flow LES, the most common way to use dynamic LES is to average Smagorinsky coefficient along the plane parallel to the wall. As OF's structured meshes are not described as i,j,k , it's not so convenient to do this kind of average. In postChannel utility, a typical method to do the average is to set a front face and walk along the normal direction to do the average of each mesh region, so the easiest way to do is like this:
1/ output the cD and cI as OF standard file
2/ call postChannel
3/ set the cD as a function of y, and match the averaged values to all the meshes

My question is： how can I define cD as a function as y and match cD to the mesh at specific y location?
(ps: this method is not efficient at all, I'll appreciate if there is more easier way)
Xianbei

huangxianbei · June 13, 2014, 00:01

Hi,all:
I think there is no need to write cD to a file, just do the collapse and then match cD at each y location. I'm wondering how can I implement this kind of match? Anyone can give me some advices?
ps:using 'if' is not a efficient way, say: if(abs(y-y_(i))<VSMALL) cD=cD(i), I think this will take a lot of time
Best regards
Xianbei

June 12, 2014, 10:33	Smagorinsky coefficient average on planes parallel to walls	#1
huangxianbei Senior Member Huang Xianbei Join Date: Sep 2013 Location: Yangzhou,China Posts: 302 Rep Power: 14	Hi,all: In channel flow LES, the most common way to use dynamic LES is to average Smagorinsky coefficient along the plane parallel to the wall. As OF's structured meshes are not described as i,j,k , it's not so convenient to do this kind of average. In postChannel utility, a typical method to do the average is to set a front face and walk along the normal direction to do the average of each mesh region, so the easiest way to do is like this: 1/ output the cD and cI as OF standard file 2/ call postChannel 3/ set the cD as a function of y, and match the averaged values to all the meshes My question is： how can I define cD as a function as y and match cD to the mesh at specific y location? (ps: this method is not efficient at all, I'll appreciate if there is more easier way) Xianbei

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June 13, 2014, 00:01		#2
huangxianbei Senior Member Huang Xianbei Join Date: Sep 2013 Location: Yangzhou,China Posts: 302 Rep Power: 14	Hi,all: I think there is no need to write cD to a file, just do the collapse and then match cD at each y location. I'm wondering how can I implement this kind of match? Anyone can give me some advices? ps:using 'if' is not a efficient way, say: if(abs(y-y_(i))<VSMALL) cD=cD(i), I think this will take a lot of time Best regards Xianbei