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-   -   comparison with DNS (http://www.cfd-online.com/Forums/main/101947-comparison-dns.html)

hars88 May 17, 2012 19:18

comparison with DNS
 
I have been trying to perform CFD analysis of isotropic turbulence using LES like scheme. In order to compare my results with DNS,should I be finding the parameters like intergral length scale(to find turn over time) from my scheme or take the DNS value. Thanks a lot......

FMDenaro May 18, 2012 04:17

Quote:

Originally Posted by hars88 (Post 361746)
I have been trying to perform CFD analysis of isotropic turbulence using LES like scheme. In order to compare my results with DNS,should I be finding the parameters like intergral length scale(to find turn over time) from my scheme or take the DNS value. Thanks a lot......

compare the statistics (RMS, energy spectra), also total energy decaying (if your case is not forced) in time

hars88 May 18, 2012 17:44

Hi, thanks a lot for the reply.... when i want to plot the total energy for example, the time axis is generally non-dimensionalized which involves a length scale(integral length scale). should i obtain this value from a DNS or calculate from my code?... thnx a lot

FMDenaro May 19, 2012 04:16

in homogeneous isotropic flows the characteristic lenght scale is generally the Taylor micro-scale lambda, on whcih the Reynolds number of the computation is based too. Use information from DNS as in LES you have a cut-off of the smallest scales (only scales in the inertial range are computed) and you cannot compute the Taylor length.

hars88 May 21, 2012 18:37

thanks a lot for clarifying......


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