About the nut and nusgs

TangYuanzhe · April 9, 2018, 23:21

Hi

I have a question about the nut and nusgs files in the /0 .
In the Openfoam 2.3.0 ,there is still nusgs file in the 0/.But in the Openfoam 4.0.0,the nusgs file is replaced by nut file.
As I think，the physical meaning of both file is different.
Q:
why nusgs file can be replaced by nut file?Does that mean the boundary condition of both file is same?

clapointe · April 10, 2018, 14:43

The way that subgrid scale (SGS) viscosity is treated/named has changed for the newer OF releases. Old versions (eg 2.x) used nuSgs (see eg https://github.com/OpenFOAM/OpenFOAM...es/pitzDaily/0). The newer versions simply refer to the SGS viscosity as nut. Previous OF releases distinguished between nuSgs/muSgs for incompressible/compressible solvers. This is done behind the scenes in newer OF releases. Check out the tutorials for various ways to set boundary conditions for nut.

Caelan

April 9, 2018, 23:21	About the nut and nusgs	#1
TangYuanzhe New Member Join Date: Aug 2017 Posts: 9 Rep Power: 8	Hi I have a question about the nut and nusgs files in the /0 . In the Openfoam 2.3.0 ,there is still nusgs file in the 0/.But in the Openfoam 4.0.0,the nusgs file is replaced by nut file. As I think，the physical meaning of both file is different. Q: why nusgs file can be replaced by nut file?Does that mean the boundary condition of both file is same?

April 10, 2018, 14:43		#2
clapointe Senior Member Join Date: Aug 2015 Posts: 494 Rep Power: 14	The way that subgrid scale (SGS) viscosity is treated/named has changed for the newer OF releases. Old versions (eg 2.x) used nuSgs (see eg https://github.com/OpenFOAM/OpenFOAM...es/pitzDaily/0). The newer versions simply refer to the SGS viscosity as nut. Previous OF releases distinguished between nuSgs/muSgs for incompressible/compressible solvers. This is done behind the scenes in newer OF releases. Check out the tutorials for various ways to set boundary conditions for nut. Caelan Neshat and hhu_lulu like this.