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Poisson with Neumann conditions
Posted 29 juil. 2022, 04:47 UTC−4 Fluid & Heat, Studies & Solvers, Equation-Based Modeling 0 Replies
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Hi,
I'm trying to find the pressure inside a large, flat drop when it is evaporating. This involves solving
together with a decay condition at infinity. This much is fine, modelled by Dirichlet on a disk, and Dirichlet on a "large" sphere for the far-field condition, and agrees well with the analytic solution. The problem is, I next need to solve
in the disk, subject to Neumann constraints at the boundary. This is rife with problems:
is zero exactly in the disk. I actually want uflux.u, but this is a post-processing variable, so apparently I can't use it in a calculation?- I can instead locate a second "drop" a distance
normal to the first, and calculate in there, but then Poisson doesn't converge using "Coefficient Form Boundary PDE" (no unique solution to Poisson with Neumann conditions - there is an additive constant) - I've tried speficying a pointwise constraint
, but then the solver just fails to satisfy Poisson close to that point - I've tried using a Global constraint (
), but I cannot seem to get this to work - I've also tried a very small Dirichlet constraint close to
, but then Poisson also seems to fail here!
Any ideas? This all has analytic solutions to compare against.
Hello Alexander Wray
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