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turbulent viscosity ratio for jet

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Old   January 14, 2006, 17:49
Default turbulent viscosity ratio for jet
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serpil
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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.

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Old   January 17, 2006, 11:23
Default Re: turbulent viscosity ratio for jet
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J. Kim
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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.

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Old   January 17, 2006, 13:51
Default Re: turbulent viscosity ratio for jet
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serpil
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Dear Kim, thanks a lot for your comments. I will consider your advice.
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Old   September 19, 2014, 06:19
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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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