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.

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?

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.