Literature on Calculating the resolved and unresolved TKE
 

Hey Guys,

I found in this forum a link to the Ansys CFX Support Forum, in which a definition for the resolved and unresolved Turbulent Kinetic Energy is found:

https://forum.ansys.com/discussion/2...kinetic-energy

Im interested in this calculation, but i cant find any literature to support this definition of the TKE. Does someone know a good source?

The reference I use for most turbulence calculations is "Turbulence Modelling for CFD" by Wilcox.

I have taken a look, but there i only find the resolved TKE formulation, like i most of the time do when im searching for this topic. LES ist listed in this book under "New Horizons", I think its to old to have information of the energy of the unresolved part? Do you know another literature regarding this topic? :)

If you don't like my reference then you can find your own. Doing a literature study is an important skill for a researcher, so it is time to get some practise.

I really dont have anything against your literature, in fact im referencing myself often this literature. I just think it doenst provide any answer to the above mentioned question, or am getting something wrong here? This might be the case!

Im really having trouble to understand the formulation in the forum post. I think its just a modification of the eddy viscosity in the smagorinsky model: v_t=(C_s*(dxdydz)^(1/3))^2*|bar(S)|. But I really dont find any literature, giving a context between |bar(S)| and (1/3)*ShearStrainRate ?

Would you mind sharing how you would compute the turbulent kinetic energy for the Smagorinsky LES model regardless of CFD software being used?

I found two sources which helped me to figure it out.

In "Nonequilibrium energy spectrum in the subgrid-scale one-equation model in large-eddy simulation" by Horiuti and "Sub-grid Scale Modeling in Large Eddy Simulation with Variable Eddy-Viscosity Coefficient" are in my opionen two very good derivations. But I still dont get the 1/0.3 pre-factor in the equation from the official ansys forum :confused: