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Problem with Accurate flux integration using Darcy's law module

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Hi,

I have a problem about "Computing Accurate Fluxes" using Darcy's law module. According to the help document "Computing Accurate Fluxes", I used the "reacf(u)" way and integrate on the boundaries.

Attached is a simple model to illustrate my problem.

A rectangular geometry, three boundaries are set to Pressure "P0 = 0", while the right side boudary is set to "Zero flux/Symmetry".

If we check the model, first integrate the source term "Qs = 1" in the subdomain,
Result: Value of integral: 1 [m^2], Expression: 1, Subdomain: all the value is "1".

Integrate "reacf(p)" for all the boundaries,
Result: Value of sum: -1, Expression: reacf(p), Boundaries: all

Which means that the total source term integration in the subdomain equals the flowout flux. There is no problem to this step.



My problem is: When integrate only the zeroflux boudary "4", shouldn't be zero. But the results is not zero.
Value of sum: -0.010335, Expression: reacf(p), Boundary: 4

Could someone help me to explain the reason? Thanks a lot in advance.


0 Replies Last Post Jan 25, 2010, 3:25 a.m. EST
COMSOL Moderator

Hello Xiaogai Li

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