Turbulence models

Breivik · May 19, 2012, 08:36

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.

May 19, 2012, 08:36	Turbulence models	#1
Breivik New Member Breivik Join Date: Mar 2012 Location: Norway Posts: 10 Rep Power: 14	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

May 23, 2012, 11:54		#6
abdul099 Senior Member Join Date: Oct 2009 Location: Germany Posts: 636 Rep Power: 21	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. __________________ We do three types of jobs here: GOOD, FAST AND CHEAP You may choose any two!

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May 20, 2012, 01:39		#2
sanjay Member aerosapien Join Date: Sep 2010 Posts: 59 Rep Power: 15	i HAD USED K-EPSILON FOR SIMULATING TUNNEL HULL. RESULTS ARE A QUITE GOOD best regards www.aerosapien.blogspot.com

May 21, 2012, 06:54		#3
siara817 Senior Member siamak rahimi ardkapan Join Date: Jul 2010 Location: Copenhagen, Denmark Posts: 220 Rep Power: 17	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

May 21, 2012, 09:21		#4
sanjay Member aerosapien Join Date: Sep 2010 Posts: 59 Rep Power: 15	siara817 what u said is very much right best regards www.aerosapien.blogspot.com

May 23, 2012, 03:43		#5
Breivik New Member Breivik Join Date: Mar 2012 Location: Norway Posts: 10 Rep Power: 14	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.