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serpil January 14, 2006 18:49

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.


J. Kim January 17, 2006 12:23

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.


serpil January 17, 2006 14:51

Re: turbulent viscosity ratio for jet
 
Dear Kim, thanks a lot for your comments. I will consider your advice.

rachitsigh11 September 19, 2014 06:19

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


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