changing model constants in k-e turbulence model

October 2, 2006, 16:20

Hi, I would like to know if there is a way to change the Turbulent Prandtl number in CFX when I am using k-e model. This is the Pr_T ( = 1) and Pr_E (= 1.3) in the model equations. There is an option to change ce1 (1.44) and ce2 (1.92), but I cannot find one for the other constants.

Thanks

rockzh · October 2, 2006, 17:46

Dear Sunil,

Did you check under TURBULENCE MODEL/Advanced Control/K COEFFCIENTS/TURBULENT FLUX CLOSURE?

Good luck, Opaque

October 3, 2006, 10:55

Thanks for the reply. I did check that and I think it is not the same as what I am looking for. flux closure has option to change the turbulent Schmidt number which I believe is not the same as turbulent Prandtl number

October 3, 2006, 12:12

Dear Sunil,

It is just a matter of semantics..Prandtl and Schmidt numbers naming is used both ways in the turbulence community..

My personal view is that Prandtl naming is only for heat transfer. Schmidt was meant for mass transfer; however, it is the name for generalized ratio between momemtum transfer/<your physics transfer>

That is the correct parameter.. Be aware that the default value shown in the GUI is not correct.

Good luck, Opaque..

October 2, 2006, 16:20	changing model constants in k-e turbulence model	#1
Sunil Guest Posts: n/a	Hi, I would like to know if there is a way to change the Turbulent Prandtl number in CFX when I am using k-e model. This is the Pr_T ( = 1) and Pr_E (= 1.3) in the model equations. There is an option to change ce1 (1.44) and ce2 (1.92), but I cannot find one for the other constants. Thanks

October 2, 2006, 17:46	Re: changing model constants in k-e turbulence mod	#2
opaque Guest Posts: n/a	Dear Sunil, Did you check under TURBULENCE MODEL/Advanced Control/K COEFFCIENTS/TURBULENT FLUX CLOSURE? Good luck, Opaque rockzh likes this.

October 3, 2006, 10:55	Re: changing model constants in k-e turbulence mod	#3
Sunil Guest Posts: n/a	Thanks for the reply. I did check that and I think it is not the same as what I am looking for. flux closure has option to change the turbulent Schmidt number which I believe is not the same as turbulent Prandtl number

October 3, 2006, 12:12	Re: changing model constants in k-e turbulence mod	#4
opaque Guest Posts: n/a	Dear Sunil, It is just a matter of semantics..Prandtl and Schmidt numbers naming is used both ways in the turbulence community.. My personal view is that Prandtl naming is only for heat transfer. Schmidt was meant for mass transfer; however, it is the name for generalized ratio between momemtum transfer/<your physics transfer> That is the correct parameter.. Be aware that the default value shown in the GUI is not correct. Good luck, Opaque..

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