# Latest **URL:** https://fenicsproject.discourse.group/latest.md [Latest](https://fenicsproject.discourse.group/latest.md) · [Categories](https://fenicsproject.discourse.group/categories.md) · [Tags](https://fenicsproject.discourse.group/tags.md) --- ## [Announcement: ufl\_legacy and legacy dolfin](https://fenicsproject.discourse.group/t/announcement-ufl-legacy-and-legacy-dolfin/11583)
**Author:** [@dparsons](https://fenicsproject.discourse.group/u/dparsons)\ **Replies:** 3\ **Last updated:** [August 17, 2023, 1:08pm UTC](https://fenicsproject.discourse.group/t/announcement-ufl-legacy-and-legacy-dolfin/11583 "2023-08-17T13:08:49Z")
tl;dr: UFL is no longer compatible with legacy dolfin. A ufl\_legacy package will be created to help keep old dolfin projects computing. Depending on how you use ufl, you might need to replace import ufl with import ufl\_… --- ## [Read before posting: How do I get my question answered?](https://fenicsproject.discourse.group/t/read-before-posting-how-do-i-get-my-question-answered/21)
**Author:** [@jackhale](https://fenicsproject.discourse.group/u/jackhale)\ **Replies:** 1\ **Last updated:** [April 22, 2021, 2:34pm UTC](https://fenicsproject.discourse.group/t/read-before-posting-how-do-i-get-my-question-answered/21 "2021-04-22T14:34:45Z")
Here are a few tips to help get your question answered: Write your message in English. Phrase the title of your post as a question and make it meaningful. Check that your question hasn’t been asked before using the sea… --- ## [Announcement: scifem v0.24.0](https://fenicsproject.discourse.group/t/announcement-scifem-v0-24-0/19834)
**Author:** [@dokken](https://fenicsproject.discourse.group/u/dokken)\ **Replies:** 3\ **Last updated:** [September 22, 2026, 4:26pm UTC](https://fenicsproject.discourse.group/t/announcement-scifem-v0-24-0/19834 "2026-09-22T16:26:32Z")
In this release of scifem, we introduce topologically periodic meshes. For the last 5 years, the only way (as far as I am aware) of making a mesh periodic has been through the DOLFINx\_MPC library. However, this approac… --- ## [Incorrect PETSc.Mat block size when using enriched\_element](https://fenicsproject.discourse.group/t/incorrect-petsc-mat-block-size-when-using-enriched-element/19805)
**Author:** [@TimS](https://fenicsproject.discourse.group/u/TimS)\ **Replies:** 1\ **Last updated:** [September 22, 2026, 2:02pm UTC](https://fenicsproject.discourse.group/t/incorrect-petsc-mat-block-size-when-using-enriched-element/19805 "2026-09-22T14:02:13Z")
General info (even though I do not think it matters much): MacOS 26.6.1 Python 3.14.6 (conda) fenics-dolfinx 0.11.0 (conda) petsc4py 3.25.4 (conda) In my application, I am using the MINI element (P1 Lagrange enriched … --- ## [Algorithms for Adaptive Mesh Refinement /and/ Coarsening in FEniCS](https://fenicsproject.discourse.group/t/algorithms-for-adaptive-mesh-refinement-and-coarsening-in-fenics/19793)
**Author:** [@zaccandels](https://fenicsproject.discourse.group/u/zaccandels)\ **Replies:** 1\ **Last updated:** [September 21, 2026, 8:02pm UTC](https://fenicsproject.discourse.group/t/algorithms-for-adaptive-mesh-refinement-and-coarsening-in-fenics/19793 "2026-09-21T20:02:37Z")
Hi everyone, I’m using FEniCS 2019.1.0 to simulate a problem with a moving interface. It would be very nice to implement an algorithm for adaptive mesh refinement and coarsening. I’ve done some digging, and while I have… --- ## [Is dolfinx\_mpc compatible with submeshes?](https://fenicsproject.discourse.group/t/is-dolfinx-mpc-compatible-with-submeshes/19829)
**Author:** [@sbhasan](https://fenicsproject.discourse.group/u/sbhasan)\ **Replies:** 1\ **Last updated:** [September 21, 2026, 12:07pm UTC](https://fenicsproject.discourse.group/t/is-dolfinx-mpc-compatible-with-submeshes/19829 "2026-09-21T12:07:10Z")
My problem involves ufl.MixedFunctionSpace with individual function spaces defined on multiple submeshes. I need to use create\_contact\_inelastic\_condition to impose continuity on a non-conformal interface found in one of… --- ## [Sector periodicity for rotating domains](https://fenicsproject.discourse.group/t/sector-periodicity-for-rotating-domains/19826)
**Author:** [@sbhasan](https://fenicsproject.discourse.group/u/sbhasan)\ **Replies:** 4\ **Last updated:** [September 18, 2026, 2:27am UTC](https://fenicsproject.discourse.group/t/sector-periodicity-for-rotating-domains/19826 "2026-09-18T02:27:52Z")
I am considering a rotating electric machine which is efficiently solved for periodic sectors specially in 3D. Below is an exemplary image to convey the idea: I was wondering whether we have tools in dolfinx that cou… --- ## [Installation on MacOS with conda](https://fenicsproject.discourse.group/t/installation-on-macos-with-conda/19827)
**Author:** [@TimS](https://fenicsproject.discourse.group/u/TimS)\ **Replies:** 2\ **Last updated:** [September 16, 2026, 6:14pm UTC](https://fenicsproject.discourse.group/t/installation-on-macos-with-conda/19827 "2026-09-16T18:14:26Z")
I have installed conda today using the Anaconda3 distribution from Download Anaconda Distribution | Anaconda . Here is the conda info: active environment : base active env location : /opt/anaconda3 … --- ## [Distortion driven remeshing in DOLFINx](https://fenicsproject.discourse.group/t/distortion-driven-remeshing-in-dolfinx/19824)
**Author:** [@kumar](https://fenicsproject.discourse.group/u/kumar)\ **Replies:** 3\ **Last updated:** [September 14, 2026, 2:41pm UTC](https://fenicsproject.discourse.group/t/distortion-driven-remeshing-in-dolfinx/19824 "2026-09-14T14:41:35Z")
Dear all, I am planning to work on a large deformation problem in dolfinx 0.10.0 where the mesh will get distorted over time. I would like to detect when cell quality drops below a threshold, remesh the deformed domain,… --- ## [Elasto-plastic contact support in dolfinx-contact](https://fenicsproject.discourse.group/t/elasto-plastic-contact-support-in-dolfinx-contact/19796)
**Author:** [@kumar](https://fenicsproject.discourse.group/u/kumar)\ **Replies:** 1\ **Last updated:** [September 10, 2026, 3:52pm UTC](https://fenicsproject.discourse.group/t/elasto-plastic-contact-support-in-dolfinx-contact/19796 "2026-09-10T15:52:11Z")
Dear all, I am using the dolfinx-contact library for a mechanical contact problem: https://github.com/Wells-Group/asimov-contact The library provides well-developed contact detection and Nitsche-based contact formulat… --- ## [Memory allocation error when reading in cell tags from a pre-defined mesh file](https://fenicsproject.discourse.group/t/memory-allocation-error-when-reading-in-cell-tags-from-a-pre-defined-mesh-file/19808)
**Author:** [@Lev](https://fenicsproject.discourse.group/u/Lev)\ **Replies:** 3\ **Last updated:** [September 9, 2026, 7:49am UTC](https://fenicsproject.discourse.group/t/memory-allocation-error-when-reading-in-cell-tags-from-a-pre-defined-mesh-file/19808 "2026-09-09T07:49:46Z")
I’m trying to load a mesh from an XDMF and H5 file (created in Gmsh) using the following code: from mpi4py import MPI # Create the MPI communicator comm = MPI.COMM\_WORLD import dolfinx # using dolfinx v0.7.2 import nu… --- ## [How are 1st-order differential equations handled?](https://fenicsproject.discourse.group/t/how-are-1st-order-differential-equations-handled/19807)
**Author:** [@fea](https://fenicsproject.discourse.group/u/fea)\ **Replies:** 4\ **Last updated:** [September 8, 2026, 11:26am UTC](https://fenicsproject.discourse.group/t/how-are-1st-order-differential-equations-handled/19807 "2026-09-08T11:26:36Z")
I’m on Dolfinx version 0.10.0, and I wanted to perform \\int\_0^x f(x) dx by converting the integral into a 1st-order ODE \\frac{du}{dx} = f(x) \\ \\ \\ \\ \\forall x\\in 0\\le x\\le L with f(x) = 1-2x, u(L) = 0; the exact solut… --- ## [LEoPart won't compile on Mac](https://fenicsproject.discourse.group/t/leopart-wont-compile-on-mac/19650)
**Author:** [@Lev](https://fenicsproject.discourse.group/u/Lev)\ **Replies:** 4\ **Last updated:** [September 4, 2026, 4:42am UTC](https://fenicsproject.discourse.group/t/leopart-wont-compile-on-mac/19650 "2026-09-04T04:42:40Z")
(I’m not sure if this is the correct place to ask about this - I’ve seen that someone else has posted an issue on the LEoPart Github but I wanted to see if anyone has figured it out here.) I’m trying to install LEoPart … --- ## [FEniCS + dolfin-adjoint in the Mosaic benchmark suite](https://fenicsproject.discourse.group/t/fenics-dolfin-adjoint-in-the-mosaic-benchmark-suite/19782)
**Author:** [@dionhaefner](https://fenicsproject.discourse.group/u/dionhaefner)\ **Replies:** 1\ **Last updated:** [September 1, 2026, 9:16pm UTC](https://fenicsproject.discourse.group/t/fenics-dolfin-adjoint-in-the-mosaic-benchmark-suite/19782 "2026-09-01T21:16:35Z")
Hi FEniCS folks, We just released Mosaic (github.com/pasteurlabs/mosaic), a benchmark for differentiable physics solvers. Each solver runs in a container behind a uniform apply / vjp interface, so one harness compares g… --- ## [Element type mixtures not allowed?](https://fenicsproject.discourse.group/t/element-type-mixtures-not-allowed/18309)
**Author:** [@ormkotta](https://fenicsproject.discourse.group/u/ormkotta)\ **Replies:** 3\ **Last updated:** [September 1, 2026, 12:40pm UTC](https://fenicsproject.discourse.group/t/element-type-mixtures-not-allowed/18309 "2026-09-01T12:40:30Z")
My noob random walk in the world of FEniCS/dolfinx has recently allowed me to generate 2D meshes with gmsh, which I then import with dolfinx.io.gmshio.read\_from\_mesh.I have even managed to get PyVista up and running insi… --- ## [Newton solver fails to converge for 1D nonlinear KDV equation with mixed boundary conditions](https://fenicsproject.discourse.group/t/newton-solver-fails-to-converge-for-1d-nonlinear-kdv-equation-with-mixed-boundary-conditions/19806)
**Author:** [@xavier](https://fenicsproject.discourse.group/u/xavier)\ **Replies:** 1\ **Last updated:** [August 24, 2026, 6:44am UTC](https://fenicsproject.discourse.group/t/newton-solver-fails-to-converge-for-1d-nonlinear-kdv-equation-with-mixed-boundary-conditions/19806 "2026-08-24T06:44:04Z")
Hello FEniCS community, I am trying to solve a one-dimensional nonlinear PDE using finite element method. The nonlinear system is solved using the Newton method, but the Newton iterations fail to converge. My boundary … --- ## [Real-space Lagrange multiplier constraint silently violated (non-deterministically) when a periodic MPC slave/master pair spans different MPI ranks — reproducible on v0.10.5 and v0.11.0](https://fenicsproject.discourse.group/t/real-space-lagrange-multiplier-constraint-silently-violated-non-deterministically-when-a-periodic-mpc-slave-master-pair-spans-different-mpi-ranks-reproducible-on-v0-10-5-and-v0-11-0/19804)
**Author:** [@czolesi1](https://fenicsproject.discourse.group/u/czolesi1)\ **Replies:** 5\ **Last updated:** [August 21, 2026, 6:58pm UTC](https://fenicsproject.discourse.group/t/real-space-lagrange-multiplier-constraint-silently-violated-non-deterministically-when-a-periodic-mpc-slave-master-pair-spans-different-mpi-ranks-reproducible-on-v0-10-5-and-v0-11-0/19804 "2026-08-21T18:58:08Z")
I’m solving a periodic elasticity/Poisson-type problem where the periodic fluctuation field v (in a MultiPointConstraint-constrained space V) has its mean pinned to zero via a scalar Lagrange multiplier gamma living in a… --- ## [How to extract oriented facet connectivity from a mesh?](https://fenicsproject.discourse.group/t/how-to-extract-oriented-facet-connectivity-from-a-mesh/19797)
**Author:** [@MathPhy42](https://fenicsproject.discourse.group/u/MathPhy42)\ **Replies:** 4\ **Last updated:** [August 14, 2026, 3:22pm UTC](https://fenicsproject.discourse.group/t/how-to-extract-oriented-facet-connectivity-from-a-mesh/19797 "2026-08-14T15:22:23Z")
Hi everyone, I’m trying to extract the (oriented) connectivity array for a surface of my mesh, which can lie on the boundary or be an internal surface as well. I know you can simply get the connectivity array calling f2… --- ## [Announcing FEniCS 2026: 17-19 June 2026 at Paris, at the University of Chicago | John W. Boyer Center, France](https://fenicsproject.discourse.group/t/announcing-fenics-2026-17-19-june-2026-at-paris-at-the-university-of-chicago-john-w-boyer-center-france/19613)
**Author:** [@a-latyshev](https://fenicsproject.discourse.group/u/a-latyshev)\ **Replies:** 9\ **Last updated:** [August 12, 2026, 7:34am UTC](https://fenicsproject.discourse.group/t/announcing-fenics-2026-17-19-june-2026-at-paris-at-the-university-of-chicago-john-w-boyer-center-france/19613 "2026-08-12T07:34:51Z")
Dear all, We are pleased to mention here on the Discourse that the final abstract submission deadline for the FEniCS 2026 conference is approaching soon: 27 March 2026! Join us in Paris from 17–19 June 2026 at the Univ… --- ## [ImportError on calling dolfinx.fem.form](https://fenicsproject.discourse.group/t/importerror-on-calling-dolfinx-fem-form/19792)
**Author:** [@William\_Graham](https://fenicsproject.discourse.group/u/William_Graham)\ **Replies:** 10\ **Last updated:** [August 11, 2026, 7:35am UTC](https://fenicsproject.discourse.group/t/importerror-on-calling-dolfinx-fem-form/19792 "2026-08-11T07:35:47Z")
I’m trying to solve a complex eigenvalue problem. I’ve installed anaconda using homebrew, and created an environment with conda create -n fenicsx-cmplx-env -c conda-forge fenics-dolfinx "petsc==complex" "petsc4py==compl… --- ## [Multphenicsx installation for dolfinx 0.10.0](https://fenicsproject.discourse.group/t/multphenicsx-installation-for-dolfinx-0-10-0/19789)
**Author:** [@Kim\_J](https://fenicsproject.discourse.group/u/Kim_J)\ **Replies:** 2\ **Last updated:** [August 9, 2026, 11:27pm UTC](https://fenicsproject.discourse.group/t/multphenicsx-installation-for-dolfinx-0-10-0/19789 "2026-08-09T23:27:25Z")
I want to ask compatibility question about multphenicsx. As dolfinx upgrade to 0.11 version. Also there is modification in the nonlinearproblem class. Can I installed the multphenicsx in same fashion as up till dolfinx 0… --- ## [Time-dependent mesh-output with higher order elements](https://fenicsproject.discourse.group/t/time-dependent-mesh-output-with-higher-order-elements/19788)
**Author:** [@MathPhy42](https://fenicsproject.discourse.group/u/MathPhy42)\ **Replies:** 3\ **Last updated:** [August 6, 2026, 2:00pm UTC](https://fenicsproject.discourse.group/t/time-dependent-mesh-output-with-higher-order-elements/19788 "2026-08-06T14:00:56Z")
Hi everyone, I want to use some ALE-method with remeshing, but I have problems writing my velocity field, which is composed of second order Lagrange-elements, in a single output file. I have tried all 3 types of writer… --- ## [Discrepancy in fem.Expression interpolation between DOLFINx 0.9 and 0.11](https://fenicsproject.discourse.group/t/discrepancy-in-fem-expression-interpolation-between-dolfinx-0-9-and-0-11/19786)
**Author:** [@Nathan\_Langlet](https://fenicsproject.discourse.group/u/Nathan_Langlet)\ **Replies:** 1\ **Last updated:** [July 30, 2026, 12:52pm UTC](https://fenicsproject.discourse.group/t/discrepancy-in-fem-expression-interpolation-between-dolfinx-0-9-and-0-11/19786 "2026-07-30T12:52:28Z")
Hi everyone, I’ve recently upgraded my solver from DOLFINx 0.9 to 0.11 and noticed a small discrepancy in my non-linear solver’s convergence history. After investigating, the only difference I could find is in the L2 no… --- ## [Changing to different C-/C++-Compiler for the conda installation](https://fenicsproject.discourse.group/t/changing-to-different-c-c-compiler-for-the-conda-installation/17804)
**Author:** [@MathPhy42](https://fenicsproject.discourse.group/u/MathPhy42)\ **Replies:** 2\ **Last updated:** [July 30, 2026, 10:15am UTC](https://fenicsproject.discourse.group/t/changing-to-different-c-c-compiler-for-the-conda-installation/17804 "2026-07-30T10:15:28Z")
Is it possible to change the C/C++ Compiler used by ffcx, when installing fenicsx with conda? I’m working on Linux (openSUSE Leap 15.6) and have installed fenicsx via conda as described on Download | FEniCS Project, but … --- ## [Plot of quadrilateral mesh shows triangles](https://fenicsproject.discourse.group/t/plot-of-quadrilateral-mesh-shows-triangles/19785)
**Author:** [@William\_Graham](https://fenicsproject.discourse.group/u/William_Graham)\ **Replies:** 5\ **Last updated:** [July 29, 2026, 8:19am UTC](https://fenicsproject.discourse.group/t/plot-of-quadrilateral-mesh-shows-triangles/19785 "2026-07-29T08:19:23Z")
I’m running fenics 0.11, downloaded via conda, on macOS 13.7.7. To familiarise myself with fenics, I’ve been editing the example in Chapter 1 of the tutorial. I changed the cell type to quadrilateral, but still see a m… --- ## [Coupled problem with codim 1 submesh wrong derivative](https://fenicsproject.discourse.group/t/coupled-problem-with-codim-1-submesh-wrong-derivative/19688)
**Author:** [@RemDelaporteMathurin](https://fenicsproject.discourse.group/u/RemDelaporteMathurin)\ **Replies:** 6\ **Last updated:** [July 29, 2026, 3:25am UTC](https://fenicsproject.discourse.group/t/coupled-problem-with-codim-1-submesh-wrong-derivative/19688 "2026-07-29T03:25:59Z")
Hi all, I’m trying to solve the following problem where \\Omega is a 2D domain and \\Gamma\_1 is a 1D submesh (bottom boundary). The governing equation on \\Omega is diffusion with coupling term J and the governing equatio… --- ## [Mixing dolfinx\_mpc and scifem packages](https://fenicsproject.discourse.group/t/mixing-dolfinx-mpc-and-scifem-packages/18310)
**Author:** [@Ergonsa](https://fenicsproject.discourse.group/u/Ergonsa)\ **Replies:** 4\ **Last updated:** [July 20, 2026, 5:06pm UTC](https://fenicsproject.discourse.group/t/mixing-dolfinx-mpc-and-scifem-packages/18310 "2026-07-20T17:06:29Z")
Hello everyone, after the announcement of dolfinx v0.10.0, I decided to retake the issue of Mixing dolfinx\_mpc and scifem packages for a nonlinear problem in which I tried to solve an homogenisation problem, i.e., with p… --- ## [NewtonSolver in v11](https://fenicsproject.discourse.group/t/newtonsolver-in-v11/19778)
**Author:** [@lclaire](https://fenicsproject.discourse.group/u/lclaire)\ **Replies:** 2\ **Last updated:** [July 20, 2026, 1:51pm UTC](https://fenicsproject.discourse.group/t/newtonsolver-in-v11/19778 "2026-07-20T13:51:13Z")
Hello, I am trying to run the hyperelasticity demo from Hyperelasticity — Computational Mechanics Numerical Tours with FEniCSx , but I get the following error message, related to NewtonSolver in NonlinearProblem: Traceb… --- ## [AV formulation with fieldsplit Hypre AMS](https://fenicsproject.discourse.group/t/av-formulation-with-fieldsplit-hypre-ams/19727)
**Author:** [@mattiafilips](https://fenicsproject.discourse.group/u/mattiafilips)\ **Replies:** 4\ **Last updated:** [July 20, 2026, 12:51pm UTC](https://fenicsproject.discourse.group/t/av-formulation-with-fieldsplit-hypre-ams/19727 "2026-07-20T12:51:41Z")
Hi, I am trying to solve the low frequency magnetoquasistatic equation with AV formulation with Coulomb gauge. I use Nedelec1 for A, CG1 for the scalar potential V and the lagrange multipliers used to force the A gauge.… --- ## [Projecting an expression onto a boundary submesh](https://fenicsproject.discourse.group/t/projecting-an-expression-onto-a-boundary-submesh/19772)
**Author:** [@rmsc](https://fenicsproject.discourse.group/u/rmsc)\ **Replies:** 8\ **Last updated:** [July 20, 2026, 12:09pm UTC](https://fenicsproject.discourse.group/t/projecting-an-expression-onto-a-boundary-submesh/19772 "2026-07-20T12:09:51Z")
I’m trying to do this projection as part of a post-processing step. I have a Function over the entire volume, and I want to plot an expression containing that Function on a few boundaries. I think this should illustrate… [Next page](https://fenicsproject.discourse.group/latest.md?page=1)