Species Transport: How to determine the mass flux from concentration gradients?

Zaphod'sSecondHead · August 12, 2013, 11:44

Dear members,

I am modeling steady state diffusion using the species transport model for two species A & B. The geometry is a cube of air of 1 cubic centimeter with an orifice at the center of one face. The opposite face has been set as an inlet vent with defined mass fraction of species A (greater), and the lower surface of a bounded cavity beyond the orifice is set as an outlet vent to a lower mass fraction of species A (lesser).

After running the simulation, I have obtained a reasonably realistic concentration distribution of species A in the volume, i.e. I have the values of the concentration of species A at every point in the volume.

My problem is, how do I calculate the resultant rate of mass diffusion across the cavity in terms of [M][T]^(-3)?

Please help me.

seanread · January 9, 2016, 04:12

Did you have any luck with this? I'm tackling more or less the same problem at the moment...

Zaphod'sSecondHead · January 9, 2016, 09:16

I had to switch to writing my own code, as Fluent couldn't offer multicomponent multiphase diffusion with ionic interactions.

August 12, 2013, 11:44	Species Transport: How to determine the mass flux from concentration gradients?	#1
Zaphod'sSecondHead New Member Saumitra Joshi Join Date: Dec 2012 Posts: 14 Rep Power: 14	Dear members, I am modeling steady state diffusion using the species transport model for two species A & B. The geometry is a cube of air of 1 cubic centimeter with an orifice at the center of one face. The opposite face has been set as an inlet vent with defined mass fraction of species A (greater), and the lower surface of a bounded cavity beyond the orifice is set as an outlet vent to a lower mass fraction of species A (lesser). After running the simulation, I have obtained a reasonably realistic concentration distribution of species A in the volume, i.e. I have the values of the concentration of species A at every point in the volume. My problem is, how do I calculate the resultant rate of mass diffusion across the cavity in terms of [M][T]^(-3)? Please help me.

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January 9, 2016, 04:12		#2
seanread Member sean read Join Date: Sep 2014 Location: Melbourne, Australia Posts: 41 Rep Power: 12	Did you have any luck with this? I'm tackling more or less the same problem at the moment...

January 9, 2016, 09:16		#3
Zaphod'sSecondHead New Member Saumitra Joshi Join Date: Dec 2012 Posts: 14 Rep Power: 14	I had to switch to writing my own code, as Fluent couldn't offer multicomponent multiphase diffusion with ionic interactions.