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Inegral as boundary condition

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How to solve Poisson's equation (or any) (u is dependent variable) when we have integral as boundary condition, for example int(u)=2 over boundary of domain (or part of boundary).

Equation:
Laplace(u)=f

and BC
int(u)=2.

2 Replies Last Post 2015年10月27日 GMT-4 08:56
Jeff Hiller COMSOL Employee

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Posted: 9 years ago 2015年10月27日 GMT-4 08:31
Hello Tomasz,
Such a problem can easily be ill-posed.
The attached file illustrates one way to set this up, but it also illustrates the risk: there is an infinite number of solutions (one for each alpha).
Best regards,
Jeff
Hello Tomasz, Such a problem can easily be ill-posed. The attached file illustrates one way to set this up, but it also illustrates the risk: there is an infinite number of solutions (one for each alpha). Best regards, Jeff


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Posted: 9 years ago 2015年10月27日 GMT-4 08:56
Thank you!

Such equations and bc govern problem of torsion of multiply connected cross-sections.
Please see: attached file (page 8-9).

Tomasz
Thank you! Such equations and bc govern problem of torsion of multiply connected cross-sections. Please see: attached file (page 8-9). Tomasz

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