K-episilon viscous model----Constant value.

August 13, 2001, 22:54

If I use K-episilon model, there are two values to set for boudary conditions: Turb. Kinetic Energy and Turb.dissipation Rate. Both of the default values are one ( constant value).

How will they influence the convergence?

August 14, 2001, 01:54

I always use the hydraulic diameter. I think it is more easy. Because you can estiamte the diameter from your geometry. And use for heavy turbulence 10 % turbulence intensity.

Armin

August 14, 2001, 07:28

Hi all,

Yes, I use hydraulic diameter and turbulent intensity, mainly because I know the hydraulic diameter roughly.

Can anyne point me in the direction of papers dealing with boundary condition values for k and epsilon for pumps. I would like to see some typical values. Also, do my INITIAL condition k and epsilon radically effect the solution? I don't think they do (from testing), but I'm wondering if they should...at least in a significant way !! ?? Thanks.

August 16, 2001, 11:55

But I use air as the fluid to calculate. And can you tell me haw much the values are?

August 13, 2001, 22:54	K-episilon viscous model----Constant value.	#1
Jie Guest Posts: n/a	If I use K-episilon model, there are two values to set for boudary conditions: Turb. Kinetic Energy and Turb.dissipation Rate. Both of the default values are one ( constant value). How will they influence the convergence?

August 14, 2001, 01:54	Re: K-episilon viscous model----Constant value.	#2
Armin Gips Guest Posts: n/a	I always use the hydraulic diameter. I think it is more easy. Because you can estiamte the diameter from your geometry. And use for heavy turbulence 10 % turbulence intensity. Armin

August 14, 2001, 07:28	Re: K-episilon viscous model----Constant value.	#3
Question Man. Guest Posts: n/a	Hi all, Yes, I use hydraulic diameter and turbulent intensity, mainly because I know the hydraulic diameter roughly. Can anyne point me in the direction of papers dealing with boundary condition values for k and epsilon for pumps. I would like to see some typical values. Also, do my INITIAL condition k and epsilon radically effect the solution? I don't think they do (from testing), but I'm wondering if they should...at least in a significant way !! ?? Thanks.

August 16, 2001, 11:55	Re: K-episilon viscous model----Constant value.	#4
Jie Guest Posts: n/a	But I use air as the fluid to calculate. And can you tell me haw much the values are?

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