how to decide viscosity for DNS

January 21, 2003, 23:54

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

January 22, 2003, 01:33

Hi,

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

Chai

January 22, 2003, 04:16

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

January 22, 2003, 09:13

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.

January 21, 2003, 23:54	how to decide viscosity for DNS	#1
Jen Guest Posts: n/a	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

January 22, 2003, 01:33	Re: how to decide viscosity for DNS	#2
Chai Guest Posts: n/a	Hi, If it is DNS, viscosity should be based upon physics rather than "chosen", IMHO. Hope it helps. Chai

January 22, 2003, 04:16	Re: how to decide viscosity for DNS	#3
Tom Guest Posts: n/a	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

January 22, 2003, 09:13	Re: how to decide viscosity for DNS	#4
Praveen Guest Posts: n/a	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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