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Help on COMSOL Mathematics interface

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Dear all,

I need to solve a Poisson equation in which the right hand side (RHS) equals a function containing a conditional statement in terms of the solution itself. To summarize everything, it's the equation for elasto-plastic torsion of prismatic bars. However, because the RHS is lengthy, I choose to give a similar (but simplified) example of the equation as follows;

Laplacian(u) = f0+f1 over a square domain (0<=x<=1, 0<=y<=1), where f0 is a constant and
f1=du/dx+du/dy when u<c0
f1=(du/dx+du/dy)^2 when u>=c0
where c0 is a constant.
Note: In the first iteration, I need to apply small value for f0 while keeping f1 = 0. After solving for u, I will then need to add an increment to f0 and use the previous value of u as my c0 in the current step. This is how I need to continue until the final value of f0 is reached.

Please how should I define such a condition in the PDE interface in COMSOL to solve the equation?
Thank you in advance for your anticipated help.

Best regards,
Faisal

0 Replies Last Post Oct 21, 2016, 10:14 a.m. EDT
COMSOL Moderator

Hello F. Mukhtar

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