how to set nut and nuTilda?
 

What does it mean nut and nuTilda in the ras model?
What formula can get nut and nuTilda?

Greetings Aiyu and welcome to the forum!

With the help of Google and the source code documentation ( http://foam.sourceforge.net/docs/cpp/index.html ), here's what I found:

• nut: turbulence viscosity
• nuTilda: http://www.cfd-online.com/Forums/ope...t-nutilda.html

I suggest that you study the tutorials that OpenFOAM provides, where there are several examples of how "nut" and "nuTilda" are defined. You can find these tutorials by running:

Best regards,
Bruno