turbulent viscosity ratio for jet
 

Hi everybody, I try to model an axisymmetric jet behind a turbofan exhaust. The problem is that with RANS the turbulent vicosity ratio is on the order of 10e4 which seems to be high physically. There exist two stream; one with Mach 0.4, and corresponding 10% turbulent intensity, and the other with mach 0.2 and 6%turbulence intensity. Is that much turbulent viscosity physical? If not, what can be the reason for that?

Thanking to everyone in advance for time and consideration.

Re: turbulent viscosity ratio for jet
 

You may have some answers through searching this website.

My suggestion is as follows:

Test your problem by reducing the jet velocity (around 1/100 scale). If you still have the same problem, insert more meshes. or Remesh your domain.

You may try the following schemes together;

Lower relaxation factors, Use different initialization values, Start unsteady simulation at first.

Re: turbulent viscosity ratio for jet
 

Dear Kim, thanks a lot for your comments. I will consider your advice.

Hi serpil..........i am doing simulations for normal shock at Mach = 2 at high altitudes. But i am not able to find what the value of turbulent viscosity ratio would be at such high altitudes and high reynolds number. Can u give some reference for find the value of turbulent viscosity ratio.

Also how u got this value " with RANS the turbulent vicosity ratio is on the order of 10e4". Thanks