# k-e turbulence

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 June 2, 2005, 18:43 k-e turbulence #1 hung Guest   Posts: n/a Hi everyone! Now I'm modeling a turbulence flow over the spheroid by Fluent, and I used K-epsilon model. But my result ( Cf, Cp....) are quite difference to the results in the paper. I used the K-epsilon, but I'm not sure about the coefficients in this model, for example k, epsilon.... Somebody can recommand to me, how to simulate it to get a better result. Thanks a lot! pah

 June 2, 2005, 21:02 Re: k-e turbulence #2 zxaar Guest   Posts: n/a read the discussion "Which do you prefer? 6.1 or6.2?" on this page, there what ever i have said is applicable to the case you are talking about.

 June 3, 2005, 01:09 Re: k-e turbulence #3 hung Guest   Posts: n/a Thanks for your reply! I'm doing with the Prolate spheroid 6:1 and it has angle of attach 10, 20 deg at Re=4.2*1e6. And I did with k=0.1, epsilon=0.1. But the result so bad. Somebody, Plz recommand to me the way to simulate it. Thanks one more! PAH

 June 3, 2005, 02:14 Re: k-e turbulence #4 zxaar Guest   Posts: n/a did you read the discussion i suggested to read,

 June 3, 2005, 02:46 Re: k-e turbulence #5 hung Guest   Posts: n/a Hi zxaar! I did, that's great and detail guiding. But my problem now is Turbulence models only. Because I want to complete turbulence model at the Steaty state case first, if it's true then I go to unsteady case. Therefore, I'm considering the Tur coefficients. Could you recommand some ideas about it to me! Thanks a lot! PAH

 June 3, 2005, 03:25 Re: k-e turbulence #6 zxaar Guest   Posts: n/a see if you have to stik to steady state calculations of k-e type, the best results you get with k-e realisable, and if u can have yplus near to 1, use enhanced wall functions, but with k-e type models you will need prism mesh near to walls of your body. and using yplus near to 1 is your best bet. i suppose RSM should also give good results but i haven't tried it yet. note using prism near to walls gives best pressure coefficient predictions.

 June 3, 2005, 03:46 Re: k-e turbulence #7 hung Guest   Posts: n/a Thanks for your recommand! I use the k-e model and my grid on the wall is hex, because the hybrid grid is used in my model in some blocks. And then, at the Models is set up with k-e realisable. But in the Inlet BC, we need to set up K, epsilon. In here, I'm trouble. I just set them as I mentioned. Thanks ! PAH

 June 3, 2005, 03:52 Re: k-e turbulence #8 zxaar Guest   Posts: n/a use intensity and lengh scale instead, read what manual has to say about it, in the boundary conditions part, then judge what you want to set,

 June 3, 2005, 05:38 Re: k-e turbulence #9 hung Guest   Posts: n/a I want to set the dimensionless model of flow over the spheroid, and then I use the Velocity inler is U=1 with the long axe a=1. Do you have some ideas about dimensionless in Fluent? Thanks a lot, Zxaaz! PAH

 June 3, 2005, 06:34 Re: k-e turbulence #10 zxaar Guest   Posts: n/a nope i never tried that

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