On 08/27/2018 07:52 AM, [email protected] wrote:
What I meant is for the interface condition to hold weakly on the
boundary and that, as you correctly pointed out, the jump in the
gradient should equal the pressure times the normal vector. As such, I
specified a pressure which I know integrates to zero on the interface,
and since my velocity is the same expression on either side of the
interface I would expect it to integrate to zero too. When I run the
code by specifying the same model over the whole domain I get what I
would expect. When I allow for the interface then the pressure shoots
off to infinity at the intersection of the interface and the boundary
(where I specify homogeneous dirichlet for the velocity). I then also
get an unexpected non-zero jump in the pressure gradient. I am
currently trying to work around that issue.
What I was commenting on is that in the formula you gave:
> Thank you for your reply. My interface condition is
\integral_{Interface}
> p*I*n_stokes - jump(velocity_gradient) ds,
...there is no test function. In other words, this formula would suggest
that the *integral* of the jump in tractions is zero, but I'm actually
pretty sure that you want this to hold in a pointwise sense or, if you
want to write it as an integral, in the weak form as
\int_Interface (p*I*n - jump(velocity_gradient) * phi ds
where phi=phi(s) is a test function. Is this not correct?
If this *is* correct, it's not enough to specify a pressure that
*integrates* to zero, but I think you want it to be exactly zero along
the interface.
Best
W.
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Wolfgang Bangerth email: [email protected]
www: http://www.math.colostate.edu/~bangerth/
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