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Calculation of fluid flux
Posted Feb 15, 2011, 7:46 a.m. EST Version 4.1 2 Replies
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Dear all,
in older versions of comsol, there used to be a variable that one could integrate in order to get the fluid flow across a boundary, which was called something like flux (I can't quite remember its name).
How can I integrate the fluid flow rate (e.g. in Darcy's law module) in m3/sec across a model boundary in version 4.1?
There is no such variable called flux or similar.
Would dl.U be what I need?
Thanks a lot and best regards,
Juergen
in older versions of comsol, there used to be a variable that one could integrate in order to get the fluid flow across a boundary, which was called something like flux (I can't quite remember its name).
How can I integrate the fluid flow rate (e.g. in Darcy's law module) in m3/sec across a model boundary in version 4.1?
There is no such variable called flux or similar.
Would dl.U be what I need?
Thanks a lot and best regards,
Juergen
2 Replies Last Post Jan 7, 2014, 1:49 p.m. EST
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Posted:
1 decade ago
Hi
normally you find the correct variables in the "Results - Derived Values - right click - domain=volume, boundary=surface, ... integration" node >< green/red arrow or justa CNTRL enter in the formula field => then select from list
Unfortunately the units are not shown (before you load the variable) so you must know what you are looking for. When I'm lost, I turn on the equations view (on by default for me) in the preferences, and I scan through the internal variables of COMSOL appearing in the last sub-node
--
Good luck
Ivar
normally you find the correct variables in the "Results - Derived Values - right click - domain=volume, boundary=surface, ... integration" node >< green/red arrow or justa CNTRL enter in the formula field => then select from list
Unfortunately the units are not shown (before you load the variable) so you must know what you are looking for. When I'm lost, I turn on the equations view (on by default for me) in the preferences, and I scan through the internal variables of COMSOL appearing in the last sub-node
--
Good luck
Ivar
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Posted:
1 decade ago
This is an old question now, but here's how to do it. Under definitions, define an integration (Definitions > Component Coupling > Integration), selecting the boundary across you want to integrate. After running the simulation, define a global evaluation (Derived Values > Global Evaluation). Then, integrate for a variable across the boundary by entering an expression with the following form: <name of integration>(<interface name>.<variable>).