CFD Online Discussion Forums

CFD Online Discussion Forums (
-   FLUENT (
-   -   Turbulent Kinetic Energy (

Olga October 8, 2002 09:42

Turbulent Kinetic Energy
I have been working with internal flows involving different types of turbulence promoters ("turbs"). For such flows it is very difficult to judge, if it is in a laminar or turbulent regime - traditional Reynolds numbers values do not work for those geometries. It is always flow separations, recirculations, vortices, even for very low Reynolds numbers. I was suggested to solve the problem as turbulent and check out the Turbulence Kinetic Energy values, in order to make sure, whether there is a turbulent regime or laminar. I am wondering, is there any border values for Turbulent Kinetic Energy in order to judge which model to use - turbulent or laminar? Is there any other checks for that? Thank you very much for your help.

Chetan Kadakia October 9, 2002 18:57

Re: Turbulent Kinetic Energy
I would say that if the flow is completely laminar then k should equal zero. But if you are in transition, then it is difficult.

Are the vortices in your problem of great concern? If so, then I might recommend LES if you have the computational power to run a fine mesh with small time step. Do you?

Olga October 11, 2002 15:05

Re: Turbulent Kinetic Energy
Thank you very much for your response.

No, we don't have the computational power to run LES.

My problem is - I am not sure which viscous model to use - laminar or turbulent. In fact, when I define viscous model as turbulent in Fluent, k is never equal to 0. Even though velocities and Re numbers are very low, there are always some local vortices, when modeling the flow for turbulence promoters.

Thanks again.

All times are GMT -4. The time now is 10:19.