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Time integration inaccuracy

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I implemented time integration of the convective diffusion flux, as I learned from this forum. It works as supposed, but it is rather inaccurate, mass balance deviates ca. 10%. Then I integrated the flux out of the system (surface integration of the total flux magnitude), exported the table in Excel where I made time integration manually. Now, the mass balance agrees with less than 1% accuracy. Hence, can I improve the time integration somehow in Comsol? It would save a lot of time.

2 Replies Last Post Jan 6, 2012, 3:28 a.m. EST
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago Jan 5, 2012, 10:16 a.m. EST
Hi

are you talking about the new v4.2a "timeint(t1,t2,expr,tol,minlen)" (see the latest help) ?

I'm using it, but I haven't really tested it carefully, as currently I do not have an easy way to check. Another way would be to new dependent variable, as per KB explanations

--
Good luck
Ivar
Hi are you talking about the new v4.2a "timeint(t1,t2,expr,tol,minlen)" (see the latest help) ? I'm using it, but I haven't really tested it carefully, as currently I do not have an easy way to check. Another way would be to new dependent variable, as per KB explanations -- Good luck Ivar

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Posted: 1 decade ago Jan 6, 2012, 3:28 a.m. EST
No, I am not using 4.2a because my model built in 4.2 does not work in the new version. Mapped mesh causes an error message.

The method I use is to define an integration coupled variable and a global ODE, a note which I found here earlier.
No, I am not using 4.2a because my model built in 4.2 does not work in the new version. Mapped mesh causes an error message. The method I use is to define an integration coupled variable and a global ODE, a note which I found here earlier.

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