As a prelude to something more complex, I’d like to solve -\nabla^2 u = \delta(\mathbf{x}- \mathbf{x}_0) \tag{1} on the unit circle. Given a finite-dimensional space of test functions V_h = \mathrm{span}(\{\phi_i| i = 1,...,n\}), it seems like the most accurate way to solve (1) would be to take i…

Have you used the search button? This question was discused serveral times, and as of December 2023 there is a solution. I’ll leave you to find it, but once you do please post a reply with the link.

For anyone who may have a similar question, a solution was given here - Delta Implementation - by dokken (post 4). Given a rhs function \delta(\mathbf{x} - \mathbf{x}_0), the solution provided allows one to evaluate the basis functions \phi_i st \mathbf{x}_0 \in \mathrm{supp}(\phi_i).

Following my post above, with a minor adaptations, a point source can be implemented as follows: # Create a point source for Poisson problem # Author: Jørgen S. Dokken # SPDX-License-Identifier: MIT from mpi4py import MPI from petsc4py import PETSc import dolfinx import dolfinx.fem.petsc import n…

Copied and pasted program and get this error AttributeError: ‘dolfinx.cpp.mesh.Geometry_float64’ object has no attribute ‘cmaps’. Did you mean: ‘cmap’? running dolfinx in fenicsx-env on a Mac. DOLFINx version: 0.8.0 based on GIT commit: of GitHub - FEniCS/dolfinx: Next generation FEniCS problem …

The api slightly changed. Try to change it ss the error message suggests.

For dolfinx 0.8.0, simply use cmap = mesh.geometry.cmap. For dolfinx main branch (future 0.9.0), a few further changes in the call to dolfinx.cpp.geometry.determine_point_ownership are required due to Make standalone function for interpolation over non-matching meshes (… · FEniCS/dolfinx@ab79530 · …

mesh.geometry.cmap worked! Thank you! I am still making sure I understand how code works, so I may be back later!

Is it possible to adapt this solution for Helmholtz equation? I just executed it with complex fenics (0.8, conda) and got the following error: { "name": "TypeError", "message": "apply_lifting(): incompatible function arguments. The following argument types are supported: 1. apply_lifting(b: n…

Simply change [image] francesco-ballarin: bc = dolfinx.fem.dirichletbc(u_bc, dofs, V) to u_bc = dolfinx.fem.Constant(domain, dolfinx.default_scalar_type(0.0))

Point Sources (Redux)

General

zaccandels February 5, 2024, 1:43pm 5

As an addendum, would anyone mind pointing me towards some method for inserting values into a rhs vector corresponding to specific mesh cells?

How to correctly apply a point source in nonlinear problem in fenicsx

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Point Sources (Redux)

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