Apply flux on circular boundary.

Question

Hi, i am solving concentration problem. I want to apply Flux on the circular boundary.

Note: I cannot use this expression: qinner(J,n)ds

plz help me in applying Flux boundary condition on circular interface.

Thanks

Comments

Hi there,

it would be good to have some more details. What is a circular boundary (a boundary that looks like a circle?) Why can't you use that expression?

Do you have an interface or a boundary?

It would be good to clarify these points.

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Sample Domain is like this, Now i have to apply flux boundary condition on the outer circle.
I have applied like this:
J = Expression (("-1.0x[0]/0.5", "-1.0x1/0.5"), t=0.0)
n = FacetNormal(mesh)
qinner(J,n)ds

where 1.0 is the magnitude of flux i have applied and 0.5 is the radius. But not getting correct boundary condition.

Answer 1

Ok thanks.

One issue might be that

n = FacetNormal(mesh)

defines the outward normal on the whole boundary of the mesh, and not just on the outer circle. You might want to consider using subdomain markers, as e.g. described here