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a problem about user define scalars(uds)

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Old   June 24, 2012, 04:32
Question a problem about user define scalars(uds)
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chenxizhong
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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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Old   June 27, 2012, 07:40
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akm
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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.


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Originally Posted by chenxizh View Post
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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Old   June 29, 2012, 08:44
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chenxizhong
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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.
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Originally Posted by akm View Post
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.
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