Giovanni,
I have a vague recollection that that question has come up before on the
mailing list, though I don't recall the outcome. Have you searched the
archives?
It is, of course, also entirely possible that the program is wrong. The
place I would start to check is whether the integral kernels stated in
the documentation are indeed theoretically correct (or whether they are
missing a factor of 2 somewhere), and if they are correctly implemented
in the code. Both can be reasons for bugs: Just because we state
something in the documentation doesn't mean that it is correct; and we
may have wrongly implemented something that was correctly stated in the
documentation.
Best
W.
On 2/17/25 12:28, Giovanni Maria Bonvini wrote:
I am currently adapting step-34 for a BEM project in my university. I am
having some issues because I believe that the proposed analytical
solution for the 3D problem is wrong.
The problem has the following Neumann boundary conditions:
grad(phi)*n = v_inf*n
and the following analytical solution on the boundary:
phi = 1/2*(x+y+z)
The issue with this is that if we compute the gradient of this function
we get:
grad(phi)*n = 1/2*(1,1,1)*(x,y,z) = 1/2*(x+y+z)
BUT since the v_inf = (1,1,1) then v_inf*n = (x+y+z) != 1/2*(x+y+z)
(we are using n=(x,y,z) since the domain is a sphere of radius 1)
So there is this 1/2 that i disagree with. Nonetheless, the simulations
perfectly converge to the proposed exact solution (the one with the 1/2)
and I don't understand why since i believe its wrong.
Maybe some of you have already encountered this issue and you found an
answere.
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