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Time Step Information

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Hi,

my question is maybe very simple, but i didnt find a solution here yet.

In my simulation the density of my solid material changes with an chemical reaction in time, like this:

rho(t(n))=rho(t(n-1)) - (m_r/C1*C2) ; n=timesteps

where C1&C2 are constants and m_r is the reaction rate where rho(t(n-1)) is included.

I´m new to comsol and i just don´t know how to implement this code.

Thx for the help

Reiner

1 Reply Last Post 27 dic 2009, 04:36 GMT-5
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 27 dic 2009, 04:36 GMT-5
Hi

when I read your formula I see an equation developped for an iterative analysis, it's not expressed as a PDE, hence not strait pluggable into COMSOL that is first of all a PDE solver.

I would suggest that you rewrite your formula somewhat, one way is to move the density expressions to the left and consider this step difference as the first time derivative of the density, and then correct the right side, search trough the chemistry modul documentation to identify the correct application mode and try to plug the data in then.

There are a few interesting books secially on chemistry, out there too, see www.comsol.com/academic/books/

Good luck
Ivar
Hi when I read your formula I see an equation developped for an iterative analysis, it's not expressed as a PDE, hence not strait pluggable into COMSOL that is first of all a PDE solver. I would suggest that you rewrite your formula somewhat, one way is to move the density expressions to the left and consider this step difference as the first time derivative of the density, and then correct the right side, search trough the chemistry modul documentation to identify the correct application mode and try to plug the data in then. There are a few interesting books secially on chemistry, out there too, see http://www.comsol.com/academic/books/ Good luck Ivar

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