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ati_ros61 January 23, 2011 06:05

Turbulence model
 
Hi Dears
I want to simulate the undular hydraulic jump (hydraulic jump with stationary wave).In first step, I did the model with laminar flow. In next step I want to study the turbulence model in this area.
When I active k-e or RNG model, the simulation is terminated after a minute.
What should I do for the simulation?

Regards

Davahue January 24, 2011 00:27

Quote:

Originally Posted by ati_ros61 (Post 291755)
Hi Dears
I want to simulate the undular hydraulic jump (hydraulic jump with stationary wave).In first step, I did the model with laminar flow. In next step I want to study the turbulence model in this area.
When I active k-e or RNG model, the simulation is terminated after a minute.
What should I do for the simulation?

Regards

What diagnostic did you get?
May be you are using an implicit model for viscosity. I mean, RNG and k-eps are turbulence models based on a dissipation and a transport equation. In this kind of models (which involve a transport equation), viscous diffusion terms are always aproximated explicitly.

Hope it helps

ati_ros61 January 25, 2011 23:42

Quote:

Originally Posted by Davahue (Post 291817)
What diagnostic did you get?
May be you are using an implicit model for viscosity. I mean, RNG and k-eps are turbulence models based on a dissipation and a transport equation. In this kind of models (which involve a transport equation), viscous diffusion terms are always aproximated explicitly.

Hope it helps

Dear Davahue
Thank you for reply.
I used explicit model for viscousity when I do with K-e or RNG but I got same result .
I received this message from Flow3D:

============= mentor tip ===============
persistent f-packing location at t= 0.52021E+01
x= 0.99991E+01, y= 0.00000E+00, z=-0.33636E-01
i=5495, j= 2, k= 5
f= 0.96045E+00
recommend reducing cfpk by factor of 10
========================================

I change cfpk to 10 or 20 but the procedure did not change.

Regards
Ati

Davahue January 26, 2011 01:36

try with some Vof Lagrangian model and/or no F-Packing at the beginning of the simulation at least


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