a problem about user define scalars(uds)

chenxizh · June 24, 2012, 05:32

Hi, all. Recently I want to use Fluent's user define scalars(uds) in a multiphase problem . I find that the uds in multiphase has the following formulation

So I have a problem about the diffusion term. When I input the value "uds diffsivity" In "Create /Edit Material " should I multiply by the density and the voidage myself ? Or Fluent will auto multiply the voidage of the phase?
Can anybody help me? thanks.

akm · June 27, 2012, 08:40

As you can see in the uds equation, diffusivity $\Gamma^{k}_{l}$ should be given to Fluent in the form $ML^{-1}T^{-1}$ -- same units as dynamic viscosity (Pa.s).

Fluent takes care of multiplying by voidage itself.

Quote:

Originally Posted by chenxizh

Hi, all. Recently I want to use Fluent's user define scalars(uds) in a multiphase problem . I find that the uds in multiphase has the following formulation

So I have a problem about the diffusion term. When I input the value "uds diffsivity" In "Create /Edit Material " should I multiply by the density and the voidage myself ? Or Fluent will auto multiply the voidage of the phase?
Can anybody help me? thanks.

chenxizh · June 29, 2012, 09:44

Hi, So you mean that I should give the value "density multiply the diffusivity coefficention" and ignore the voidage thing, Did I get it? thanks.

Quote:

Originally Posted by akm

As you can see in the uds equation, diffusivity $\Gamma^{k}_{l}$ should be given to Fluent in the form $ML^{-1}T^{-1}$ -- same units as dynamic viscosity (Pa.s).

Fluent takes care of multiplying by voidage itself.

June 24, 2012, 05:32	a problem about user define scalars(uds)	#1
chenxizh Member chenxizhong Join Date: Feb 2012 Posts: 30 Rep Power: 14	Hi, all. Recently I want to use Fluent's user define scalars(uds) in a multiphase problem . I find that the uds in multiphase has the following formulation So I have a problem about the diffusion term. When I input the value "uds diffsivity" In "Create /Edit Material " should I multiply by the density and the voidage myself ? Or Fluent will auto multiply the voidage of the phase? Can anybody help me? thanks.

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