CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   Main CFD Forum (http://www.cfd-online.com/Forums/main/)
-   -   mesh resolution for DNS with high prandtl number (http://www.cfd-online.com/Forums/main/128395-mesh-resolution-dns-high-prandtl-number.html)

hnemati January 10, 2014 11:14

mesh resolution for DNS with high prandtl number
 
Dears
I am doing DNS with high prandtle number fluid (Pr=15).
1- Could someone tell me the best resolution for DNS.
2- For high Pr number I should go finer mesh, Could someone tell me what is the relation between Pr and factor of mesh resolution.
Bests

FMDenaro January 10, 2014 11:39

Quote:

Originally Posted by hnemati (Post 469473)
Dears
I am doing DNS with high prandtle number fluid (Pr=15).
1- Could someone tell me the best resolution for DNS.
2- For high Pr number I should go finer mesh, Could someone tell me what is the relation between Pr and factor of mesh resolution.
Bests


Just consider the Peclet number = Re*Pr in the energy equation as the same way as you consider only the Re number in the momentum

beer January 11, 2014 00:40

I think I remember from University that the resolution should be the kolmogorov length.

http://en.wikipedia.org/wiki/Kolmogorov_microscales

It is not alway ease to find the right epsilon. You can try to estimate it due to Reynolds number and boundary condition or run a coarse grid simulation with k-e turbulence.
How do you want to run a DNS anyway. I remember running some LES-code at University for several weeks on clusters (and DNS can be factors of magnitude more expensive).

Anyway, good luck and fun


All times are GMT -4. The time now is 22:02.