What is the Avearage in dynSmargrinsky model

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 July 12, 2010, 02:57 What is the Avearage in dynSmargrinsky model #1 Senior Member   wayne.zhang Join Date: Mar 2009 Location: Shanghai, Shanghai, P.R.China Posts: 307 Rep Power: 9 Dear everyone: So far as I know, in dynamic smargrinsky model, the original way to calculated cD is unstable , so ensemble average is introduced to resovle the problem such as negetive value of cD. so you can find in http://foam.sourceforge.net/doc/Doxy...agorinsky.html : cD=/, which is intead of cD=L.M/M.M, where < > means ensemble average. But I don`t know what is the " average " in the source code ? it seems like that it is the "Arithmetic average:" for the field if that the cD is not the funtion of space.as original idea for dynamic model is to make the cD to be the function of time and space--cD=cD(x,t) so if anyone can tell me where is the code of the original function type for the average here in the code Thanks 00052 00053 dimensionedScalar dynSmagorinsky::cD(const volSymmTensorField& D) const 00054 { 00055 volSymmTensorField LL = dev(filter_(sqr(U())) - (sqr(filter_(U())))); 00056 00057 volSymmTensorField MM = 00058 sqr(delta())*(filter_(mag(D)*(D)) - 4*mag(filter_(D))*filter_(D)); 00059 00060 dimensionedScalar MMMM = average(magSqr(MM)); 00061 00062 if (MMMM.value() > VSMALL) 00063 { 00064 return average(LL && MM)/MMMM; 00065 } 00066 else 00067 { 00068 return 0.0; 00069 } 00070 } 00071

 January 24, 2011, 09:54 average(volScalarField) -> implementation? #2 Member   Bernhard Grieser Join Date: Mar 2010 Location: Zurich, Switzerland Posts: 30 Rep Power: 7 I'd like to know that as well. How's average(volScalarField) implemented?

 January 24, 2011, 22:48 Hope this helps! #3 Member   Charlie Join Date: Dec 2010 Location: 415 Kinross Dr. Newark, DE 19711 Posts: 78 Rep Power: 6 Hi, See the source file about average(): http://foam.sourceforge.net/doc/Doxy...8C_source.html you can see some useful field functions( including average(),pow() etc) there

January 25, 2011, 04:24
#4
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Bernhard Grieser
Join Date: Mar 2010
Location: Zurich, Switzerland
Posts: 30
Rep Power: 7
Quote:
 Originally Posted by cheng1988sjtu See the source file about average(): http://foam.sourceforge.net/doc/Doxy...8C_source.html you can see some useful field functions( including average(),pow() etc) there
Thank you very much, Cheng!

Regards,
Bernhard

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