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Lagrange Multipliers, Laplace equation
Posted Mar 6, 2019, 6:56 a.m. EST 0 Replies
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Dear,
I am trying to understand how COMSOL use Lagrange multiplier for boundary condition for the corrosion. which is the resolution of Laplace equation, with imposing a current at the boundary.
For that I did a bar element (edge element) with 2 nodes. The first node is imposing a current (or we can do current density), at the second node is imposing a function of current density vs. potential.
We have no value of essential boundary condition (potential).
In COMSOL it works.
At the 1st node side COMSOL impose the enforce the condition:
Constraint Constraint force Shape function
siec.phil0-phil test(siec.phil0-phil) Lagrange (Linear)
siec.phil0 is Electrolyte potential on boundary.
Shape functions
Name Shape function Unit Description Shape frame Selection
siec.phil0_ic1 ODE V Electrolyte potential on boundary Global
-I tried a hand computation in attached file : newton.png, but it does'n't give the COMSOL results. Please, Can you help if you have a another point of view? Thanks, Gali
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Hello Gali Mourni
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