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HOW TO APPLY A SIMPLE CONSTRAINT IN COMSOL

Posted 26 lug 2012, 17:19 GMT-4 Chemical Reaction Engineering Version 4.2a, Version 4.3 2 Replies

Dao Trinh (COMSOL)
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This is the simple problem of the precipitation in a solution.
We got a concentration of [A+], and concentration of [B-].

And the constraint in solution is: [A+]*[B-] = Ksp (solubility constant).
Are there any way to apply this constraint, this is not reaction rate (R). It is a condition depending on [A+], and [B-] which vary with time.
2 Replies Last Post 27 lug 2012, 08:09 GMT-4
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 27 lug 2012, 04:32 GMT-4
Hi

what about adding a equation [A+]*[B-] - Ksp = 0 over your domain or bounary ?

--
Good luck
Ivar
Hi what about adding a equation [A+]*[B-] - Ksp = 0 over your domain or bounary ? -- Good luck Ivar
Dao Trinh (COMSOL)
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Posted: 1 decade ago 27 lug 2012, 08:09 GMT-4
Yes. But how to do that Ivar?
In Comsol, when we play with reaction, the equation comes with the reaction rate form.

That means: dc/dt = mass transport + rate

I'm finding the way to implement as the constraint form: [a]*[b] = constant
Yes. But how to do that Ivar? In Comsol, when we play with reaction, the equation comes with the reaction rate form. That means: dc/dt = mass transport + rate I'm finding the way to implement as the constraint form: [a]*[b] = constant

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