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dirac delta function

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Hi,
I am beginner in comsol and I am trying to solve a problem with a dirac delta function at the boundary domain. I am dealing with a bidimensional convection diffusion problem, with a source in x = 0 (the left boundary) described by: u(0,y) = delta(y-y0), with y0 the source height.
Besides, can I put it at the strong form, or I must use the weak form of the equation?
thanks in advance,
Joana.

2 Replies Last Post 4 feb 2014, 14:29 GMT-5

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Posted: 1 decade ago 17 ott 2013, 05:43 GMT-4
I would cheat a little by drawing two points very close to each other at x = 0 and y = y0, y = y0+0.001. The define that tiny bar of the length 0.001 as the inlet. In real life you do not have point sources. I wish I understood your problem correct ;)

Lasse
I would cheat a little by drawing two points very close to each other at x = 0 and y = y0, y = y0+0.001. The define that tiny bar of the length 0.001 as the inlet. In real life you do not have point sources. I wish I understood your problem correct ;) Lasse

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Posted: 1 decade ago 4 feb 2014, 14:29 GMT-5
You can simulate Dirac Delta Function by a (Gaussian pulse), which is a built-in function in COMSOL.

You can define the Gaussian pulse function as follow:
right click (Global Definitions) ==> choose (Functions) ==> Choose (Gaussian pulse)
You can simulate Dirac Delta Function by a (Gaussian pulse), which is a built-in function in COMSOL. You can define the Gaussian pulse function as follow: right click (Global Definitions) ==> choose (Functions) ==> Choose (Gaussian pulse)

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