I’m running into problems setting up the bilinear form of the problem. Assembling a vector with both dirichlet and neumann boundary conditions throws the error below: Traceback (most recent call last): File "demo_poisson.py", line 53, in <module> b = assemble_vector(L) File "/usr/lib/python…

Yes. import dolfinx import numpy as np import ufl from dolfinx.fem import (apply_lifting, assemble_matrix, assemble_vector, Constant, dirichletbc, Expression, form, Function, FunctionSpace, locate_dofs_topological, LinearProblem, set_bc, VectorFunct…

I don’t really understand what your intent is with the terms dx(x) and ds(mesh). dx(x) doesn’t make sense, and perhaps you needed the latter to actually give you a non-zero form (since UFL will optimise out zeros unless wrapped in a constant)? I’m running dolfinx@main so there are some minor change…

[image] nate: f = dolfinx.fem.Constant(mesh, PETSc.ScalarType((0.0, 0.0))) g = dolfinx.fem.Constant(mesh, PETSc.ScalarType((0.0, 0.0))) This is neat, thanks. I suppose my problem is that the form of the source and flux terms requires the domains to be passed into the dx and ds terms. It did n…

See this demo for an example of using subdomain data in ufl.Measures. Specifically, this followed by this .

Setting neumann and dirichlet boundary conditions in 2D with assemble vector

variational formulation

nate February 22, 2022, 3:55pm 2

Can you provide a MWE?

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Setting neumann and dirichlet boundary conditions in 2D with assemble vector

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