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Andrew Garrard January 20, 2005 13:20

Hello friends,

I am trying to model a convection/diffusion system using a UDS and a UDF. I am trying to model this:

del( vel * conc ) - D del[del(conc)] = 0

I am using a standard UDS with the UDF:

DEFINE_UDS_FLUX ( name, f, t, i)

{ return(F_FLUX{f, thread)/1000) }

I ran the model agains fluents standard surface reaction and mass transport model and the results came out the same. However, the results do not match with the expected results from an experiment. Is there something I am missing with the F_FLUX marco?

The part that worries me is this:

!! Note also that [psi][A] must have units of mass flow rate in SI (i.e., kg/s).

Also, as an aside, dose anyone know the difference between advection and convection? The fluent manual would suggest that advection is the transfer of a property by the motion of a fluid, but says that is to do with horizontal motion...

759599290 October 28, 2012 03:57

may be you can try this code:

DEFINE_UDS_FLUX ( name, f, t, i)

return(F_FLUX(f, t)/1000)

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