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Old   February 6, 2012, 14:04
Post species transport
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Cecília Mageski
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Hello
I need simulated a species transport. Oxygen in water, with mass fraction and diffusion coefficient, but i don't know how to do.
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Old   February 6, 2012, 20:01
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Glenn Horrocks
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Have you done the tutorials on additional variables, multicomponent and multiphase flows?
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Old   February 7, 2012, 09:04
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Yes, for multicomponent. But when I put the mass fraction of oxygen as multicomponent, the oxygen disappear in my geometry from one position. My geometry is followed by a contraction and expansion after expansion there is no oxygen in the fluid. I wonder if the CFX imposes zero mass fraction at the exit.
For additional variable, i din't understand very well the what is and din't found what tutorial . Send the name of tutorial this part talk about this exactly.
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Old   February 7, 2012, 17:16
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Can you describe what you are modelling? What is the oxygen doing in the water?
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Old   February 8, 2012, 08:23
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yes of course. I transporting oxygen through the water to find the concentration close to the wall and to estimate the corrosion according to the concentration of oxygen near the wall. but when using multicomponent transport oxygen after expansion tends to zero, oxygen is not the entire flow. The water have a saturation of the oxygen em mg/L free in water, and the oxygen a coefficient diffusion in water.
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Old   February 8, 2012, 08:24
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yes of course. I transporting oxygen through the water to find the concentration close to the wall and to estimate the corrosion according to the concentration of oxygen near the wall. but when using multicomponent transport oxygen after expansion tends to zero, oxygen is not the entire flow.
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Old   February 8, 2012, 17:44
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I would consider using an additional variable rather than a multi component mixture. Multi component mixtures are designed for multi-component gases, not gases dissolved in liquids.
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Old   February 9, 2012, 12:12
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Ok thank you. I will test.
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Old   February 15, 2012, 06:08
Thumbs up wall permeability in species transport
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Hi all,
I want to find the concentration distribution of a species in a region. The model has two zones. The distribution is being calculated in single zone only. How to include the permeability of the wall in between so that we can find the species distribution in the other zone also.

Thanks for your help.
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Old   February 15, 2012, 06:27
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Make the porous wall an interface and put a resistance coefficient on it.
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Old   February 15, 2012, 06:27
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Hi cfdplayer!
If I got you right then you have 2 (connected) domains for your problem and you want the flow to go from one to the other?
If this is your problem you must use / set up the domain interface. Chapter 13 in the cfx_pre.pdf help files of CFX.
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