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-   -   how to decide viscosity for DNS (http://www.cfd-online.com/Forums/main/5676-how-decide-viscosity-dns.html)

Jen January 21, 2003 23:54

how to decide viscosity for DNS
 
Hi, folks,

I am new to DNS. I try to figure out how to choose viscosity for DNS. I am using pseudospectral method.

Thanks,

Jen

Chai January 22, 2003 01:33

Re: how to decide viscosity for DNS
 
Hi,

If it is DNS, viscosity should be based upon physics rather than "chosen", IMHO. Hope it helps.

Chai

Tom January 22, 2003 04:16

Re: how to decide viscosity for DNS
 
What kind of flow do you want to simulate? In case of channel flow people chose their grid in terms of y^+ units. In case of isotropic turbulence k_max * Kolmogorov length scale should be equal or smaller than one. But that depends also on what kind of statistics you want to compute.

Tom

Praveen January 22, 2003 09:13

Re: how to decide viscosity for DNS
 
It is more natural to decide on a Reynolds number of your interest rather than the viscosity. Then use the equations in the non-dimensional form.


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