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Transport of Diluted Species (TDS): Determine the concentration that is flowing out a boundary

Posted 5 lug 2017, 14:13 GMT-4 1 Reply

Gustavo Dacanal
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Please, I need your help for a simple question for aplication in drying systems.
In TDS problems the total concentration of a specie C can be calculated by integration of C over the domain.
However, I want to compute the Flux on a boudary and compute the concentration that is flowing out the domain. This Flux must be integrate over the time to obtain that same values computed by direct domain integration of C. In other words, I want determine the concentration that is flowing out the boundary by integration of the Flux over the time.

Can you help me with this question?!
Thanks,
Gustavo
1 Reply Last Post 6 lug 2017, 02:02 GMT-4
Lasse Murtomäki
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Posted: 7 years ago 6 lug 2017, 02:02 GMT-4
Sure you can integrate the flux over a boundary. But your question is how to calculate the amount of material passed across the boundary over a period of time. There is a means - unfortunately I am not able to give the thread where this was discussed - that is based on defining a global integration variable. It worked, in principle, but was rather inaccurate and slowed down the computation significantly. My solution was to intergrate the flux at each time point, move the table to Excel and calculate the accumulation of material there. This kind of calculations are essential to check the mass balance in the system, as you probably are trying to do.

Best wishes
Lasse
Sure you can integrate the flux over a boundary. But your question is how to calculate the amount of material passed across the boundary over a period of time. There is a means - unfortunately I am not able to give the thread where this was discussed - that is based on defining a global integration variable. It worked, in principle, but was rather inaccurate and slowed down the computation significantly. My solution was to intergrate the flux at each time point, move the table to Excel and calculate the accumulation of material there. This kind of calculations are essential to check the mass balance in the system, as you probably are trying to do. Best wishes Lasse

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