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-   -   Turbulence models (http://www.cfd-online.com/Forums/star-ccm/101999-turbulence-models.html)

Breivik May 19, 2012 08:36

Turbulence models
 
Hi
I'm doing a full scale, calm water simulation of a ship with a free surface. In this case I wolud like to know which of turbulence model, K-epsilon or k-omega, that are best suited to use?
The domain is quite large, with the free surface having a span of 650 x 430 meters.

Any answer would be much appreciated

Breivik

sanjay May 20, 2012 01:39

i HAD USED K-EPSILON FOR SIMULATING TUNNEL HULL. RESULTS ARE A QUITE GOOD


best regards
www.aerosapien.blogspot.com

siara817 May 21, 2012 06:54

I think it can be different for every case. It is nice to search for a literature source to find out which one is proper. Otherwise you need to simulate a simple case similar to your case. Then check the some properties to see if they are realistic. You can use for example streamline and check if the behavior of your fluid is realistic.
Good luck

sanjay May 21, 2012 09:21

siara817 what u said is very much right


best regards
www.aerosapien.blogspot.com

Breivik May 23, 2012 03:43

Actually I have done the simulation with both models, and as far as I can see the water behaviour is quite similar in both cases.
The thing is: The drag coefficient differs slightly (5 - 6 %) after som 30 000 iterations.

So my question still stands
Does anyone here know which of the models that are best suited for a full scale, calm water and implicit unsteady case(the ship has 0 DOF)?
As mentioned before the domain is quite large.

abdul099 May 23, 2012 11:54

Are you sure, all other errors except the turbulence model are small enough? To be able to judge about 5% difference due to the turbulence model, you have to make sure, all other errors are significantly smaller.


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