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How are pointwise constraints implemented?

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Hello,

I understand how we can add weak constraints by explicitly adding Lagrange multipliers and multiplying by the constraint expression. I also understand how mathematically we can constrain a degree of freedom by modifying the matrix column attached to it, but I do not think that is what Comsol is doing.

In the Comsol documentation, it states that in the pointwise constraint, the Lagrange multipliers are implicitly defined and eliminated with the degrees of freedom. What is meant by implicitly defined and eliminated?

Thank you,

Alex


1 Reply Last Post Jun 17, 2020, 11:40 a.m. EDT

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Posted: 4 years ago Jun 17, 2020, 11:40 a.m. EDT
Updated: 4 years ago Jun 18, 2020, 4:05 a.m. EDT

Just found a very interesting Comsol blog explaining the difference between pointwise and weak constraints:

https://www.comsol.com/blogs/implementing-the-weak-form-with-a-comsol-app/#equation1

Cheers,

Alex

Just found a very interesting Comsol blog explaining the difference between pointwise and weak constraints: Cheers, Alex

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