# General **URL:** https://fenicsproject.discourse.group/c/general/14.md [Latest](https://fenicsproject.discourse.group/latest.md) · [Categories](https://fenicsproject.discourse.group/categories.md) · [Tags](https://fenicsproject.discourse.group/tags.md) --- ## [About the General category](https://fenicsproject.discourse.group/t/about-the-general-category/9163)
**Author:** [@system](https://fenicsproject.discourse.group/u/system)\ **Replies:** 0
--- ## [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:** 7\ **Last updated:** [October 29, 2026, 6:54pm UTC](https://fenicsproject.discourse.group/t/is-dolfinx-mpc-compatible-with-submeshes/19829 "2026-10-29T18:54:29Z")
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… --- ## [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:** 3\ **Last updated:** [October 29, 2026, 11:54am UTC](https://fenicsproject.discourse.group/t/discrepancy-in-fem-expression-interpolation-between-dolfinx-0-9-and-0-11/19786 "2026-10-29T11:54:39Z")
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… --- ## [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:** 2\ **Last updated:** [October 29, 2026, 11:52am UTC](https://fenicsproject.discourse.group/t/newton-solver-fails-to-converge-for-1d-nonlinear-kdv-equation-with-mixed-boundary-conditions/19806 "2026-10-29T11:52:52Z")
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 … --- ## [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:** 2\ **Last updated:** [October 29, 2026, 11:52am UTC](https://fenicsproject.discourse.group/t/algorithms-for-adaptive-mesh-refinement-and-coarsening-in-fenics/19793 "2026-10-29T11:52:44Z")
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… --- ## [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:** 2\ **Last updated:** [October 28, 2026, 5:54am UTC](https://fenicsproject.discourse.group/t/fenics-dolfin-adjoint-in-the-mosaic-benchmark-suite/19782 "2026-10-28T05:54:44Z")
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… --- ## [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… --- ## [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… --- ## [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… --- ## [Axisymmetric problems: Nearly incompressible linear viscoelastic solid sphere with surface tension](https://fenicsproject.discourse.group/t/axisymmetric-problems-nearly-incompressible-linear-viscoelastic-solid-sphere-with-surface-tension/19763)
**Author:** [@Jo\_A](https://fenicsproject.discourse.group/u/Jo_A)\ **Replies:** 1\ **Last updated:** [July 20, 2026, 8:13am UTC](https://fenicsproject.discourse.group/t/axisymmetric-problems-nearly-incompressible-linear-viscoelastic-solid-sphere-with-surface-tension/19763 "2026-07-20T08:13:54Z")
Deal all, I am currently trying to implement a nearly incompressible linear viscoelastic solid sphere with surface tension. The viscoelastic part is running ok but introducing surface tension is creating problems, as t… --- ## [Possible reuse of LU decomposition when solving linear elasticity problem in same mesh with diferent bcs](https://fenicsproject.discourse.group/t/possible-reuse-of-lu-decomposition-when-solving-linear-elasticity-problem-in-same-mesh-with-diferent-bcs/19765)
**Author:** [@alex24](https://fenicsproject.discourse.group/u/alex24)\ **Replies:** 10\ **Last updated:** [July 16, 2026, 3:49pm UTC](https://fenicsproject.discourse.group/t/possible-reuse-of-lu-decomposition-when-solving-linear-elasticity-problem-in-same-mesh-with-diferent-bcs/19765 "2026-07-16T15:49:44Z")
Hi, I would like to optimize a linear elasticity code to run faster by reusing the LU decomposition used by PETSc. Below I have a version of my code that runs using the function LinearProblem(), and another version whe… --- ## [Parallel Mesh Generation Using mshr and Legacy FEniCS](https://fenicsproject.discourse.group/t/parallel-mesh-generation-using-mshr-and-legacy-fenics/19687)
**Author:** [@zaccandels](https://fenicsproject.discourse.group/u/zaccandels)\ **Replies:** 3\ **Last updated:** [July 6, 2026, 5:05pm UTC](https://fenicsproject.discourse.group/t/parallel-mesh-generation-using-mshr-and-legacy-fenics/19687 "2026-07-06T17:05:43Z")
Hi everyone, I’m using FEniCS 2019.1.0 with mshr. From what I understand, mshr is serial only - however, is there a way to modify meshes generated with mshr so that I can use MPI parallelization? Consider as an example… --- ## [Why do I obtain inaccurate mode shapes from SLEPc PEP-solver for 3D elasticity problem with periodic BC?](https://fenicsproject.discourse.group/t/why-do-i-obtain-inaccurate-mode-shapes-from-slepc-pep-solver-for-3d-elasticity-problem-with-periodic-bc/19753)
**Author:** [@nadine](https://fenicsproject.discourse.group/u/nadine)\ **Replies:** 6\ **Last updated:** [July 3, 2026, 9:53am UTC](https://fenicsproject.discourse.group/t/why-do-i-obtain-inaccurate-mode-shapes-from-slepc-pep-solver-for-3d-elasticity-problem-with-periodic-bc/19753 "2026-07-03T09:53:13Z")
Hi everyone, I’m implementing an inverse dispersion solver in DOLFINx that computes complex wavenumbers k(ω) for waves in a periodic elastic 3D structure, using the SLEPc PEP-solver and Bloch periodic boundary condition… --- ## [Inverse of a SUPG term](https://fenicsproject.discourse.group/t/inverse-of-a-supg-term/19638)
**Author:** [@ruhsnay](https://fenicsproject.discourse.group/u/ruhsnay)\ **Replies:** 4\ **Last updated:** [July 2, 2026, 5:45pm UTC](https://fenicsproject.discourse.group/t/inverse-of-a-supg-term/19638 "2026-07-02T17:45:45Z")
Hello, I’m working on a SUPG-stabilised finite element solver in the FEniCSx library. Many solvers, including fund3D, Coffe …, use a very specific SUPG term and I would like to implement : in many paper we can read “… --- ## [Feasibility of piercing-type simulation in FEniCSx](https://fenicsproject.discourse.group/t/feasibility-of-piercing-type-simulation-in-fenicsx/19758)
**Author:** [@Jack1](https://fenicsproject.discourse.group/u/Jack1)\ **Replies:** 1\ **Last updated:** [July 1, 2026, 6:32pm UTC](https://fenicsproject.discourse.group/t/feasibility-of-piercing-type-simulation-in-fenicsx/19758 "2026-07-01T18:32:37Z")
Dear all, I would like to ask about the feasibility of simulating a piercing type problem in FEniCSx. The basic case is a punch moving into a sheet, where at some stage the sheet should locally separate so that the pun… --- ## [Hybrid High Order(HHO) method for Poisson Equation Fencisx demo code](https://fenicsproject.discourse.group/t/hybrid-high-order-hho-method-for-poisson-equation-fencisx-demo-code/19630)
**Author:** [@Monisaddam](https://fenicsproject.discourse.group/u/Monisaddam)\ **Replies:** 7\ **Last updated:** [June 30, 2026, 6:55am UTC](https://fenicsproject.discourse.group/t/hybrid-high-order-hho-method-for-poisson-equation-fencisx-demo-code/19630 "2026-06-30T06:55:55Z")
Hi everyone, I’m currently learning the Hybrid High-Order (HHO) method and would really appreciate some guidance. I’m looking for demo or example code using FEniCSx that implements HHO in both 2D and 3D (even simple ben… --- ## [Running two linear elastic simulations one with domain and another one after refining domain once](https://fenicsproject.discourse.group/t/running-two-linear-elastic-simulations-one-with-domain-and-another-one-after-refining-domain-once/19738)
**Author:** [@alex24](https://fenicsproject.discourse.group/u/alex24)\ **Replies:** 2\ **Last updated:** [June 29, 2026, 5:51pm UTC](https://fenicsproject.discourse.group/t/running-two-linear-elastic-simulations-one-with-domain-and-another-one-after-refining-domain-once/19738 "2026-06-29T17:51:36Z")
Hi, I was able to run two elastic simulations using the original domain, and then a subdivided domain using the following code: #Make new domain with all elements subdivided once tdim = domain.topology.dim domain.topol… --- ## [Application of Periodic Boundary Conditions with Unstructured Mesh](https://fenicsproject.discourse.group/t/application-of-periodic-boundary-conditions-with-unstructured-mesh/19750)
**Author:** [@zaccandels](https://fenicsproject.discourse.group/u/zaccandels)\ **Replies:** 1\ **Last updated:** [June 29, 2026, 12:33pm UTC](https://fenicsproject.discourse.group/t/application-of-periodic-boundary-conditions-with-unstructured-mesh/19750 "2026-06-29T12:33:04Z")
Hi everyone, I’m using FEniCS 2019.1.0 to simulate the advection of a moving peak - ie, I’m solving the PDE \\frac{\\partial u}{\\partial t} + \\mathbf{a} \\cdot \\nabla u = 0 on the domain \\Omega = (0,1) \\times (0,1) with… --- ## [I have tried HHO implementation but not getting the superconvergnce as expected for each k](https://fenicsproject.discourse.group/t/i-have-tried-hho-implementation-but-not-getting-the-superconvergnce-as-expected-for-each-k/19755)
**Author:** [@raiharsh\_123](https://fenicsproject.discourse.group/u/raiharsh_123)\ **Replies:** 0\ **Last updated:** [June 27, 2026, 9:41pm UTC](https://fenicsproject.discourse.group/t/i-have-tried-hho-implementation-but-not-getting-the-superconvergnce-as-expected-for-each-k/19755 "2026-06-27T21:41:04Z")
\#HHO DIFFUSION #Hybrid High-Order method for diffusion problem from mpi4py import MPI from dolfinx import mesh, fem, io, log import ufl import basix import numpy as np import matplotlib.pyplot as plt from scipy.s… --- ## [Dirichlet-Neumann vs. Nitsche method for conservative interface coupling of two-domain, 1D, Poisson-Nernst-Planck system](https://fenicsproject.discourse.group/t/dirichlet-neumann-vs-nitsche-method-for-conservative-interface-coupling-of-two-domain-1d-poisson-nernst-planck-system/19737)
**Author:** [@narguess](https://fenicsproject.discourse.group/u/narguess)\ **Replies:** 1\ **Last updated:** [June 25, 2026, 1:34pm UTC](https://fenicsproject.discourse.group/t/dirichlet-neumann-vs-nitsche-method-for-conservative-interface-coupling-of-two-domain-1d-poisson-nernst-planck-system/19737 "2026-06-25T13:34:36Z")
Hello All, I am solving a 1D two-domain transport problem in legacy FEniCS. The physical problem is a Poisson-Nernst-Planck type system with one domain representing a gel and the other representing a supernatant. The tw… --- ## [3D linear elasticity code with fixed facets and tranction facets not converging](https://fenicsproject.discourse.group/t/3d-linear-elasticity-code-with-fixed-facets-and-tranction-facets-not-converging/19730)
**Author:** [@alex24](https://fenicsproject.discourse.group/u/alex24)\ **Replies:** 7\ **Last updated:** [June 25, 2026, 1:24pm UTC](https://fenicsproject.discourse.group/t/3d-linear-elasticity-code-with-fixed-facets-and-tranction-facets-not-converging/19730 "2026-06-25T13:24:28Z")
Hi, I made a simple setup with a rectangular box, one side has a zero displacement boundary condition within a circle, and the other side has a traction boundary condition that integrates to 1 N. The material parameters… --- ## [Nanobind usage in v0.1\* compare to v0.9](https://fenicsproject.discourse.group/t/nanobind-usage-in-v0-1-compare-to-v0-9/19744)
**Author:** [@SalzmanA](https://fenicsproject.discourse.group/u/SalzmanA)\ **Replies:** 2\ **Last updated:** [June 24, 2026, 7:39am UTC](https://fenicsproject.discourse.group/t/nanobind-usage-in-v0-1-compare-to-v0-9/19744 "2026-06-24T07:39:34Z")
Hello, I am currently trying to port a library developed for FEniCSx v0.9 to v0.10/v0.11. The compilation goes smoothly, but when I run the program, I encounter a problem that is reproduced by the MWE below: CMakeLists.… --- ## [DG-solver for CHNS equations](https://fenicsproject.discourse.group/t/dg-solver-for-chns-equations/19736)
**Author:** [@jlin](https://fenicsproject.discourse.group/u/jlin)\ **Replies:** 3\ **Last updated:** [June 15, 2026, 4:46pm UTC](https://fenicsproject.discourse.group/t/dg-solver-for-chns-equations/19736 "2026-06-15T16:46:39Z")
Hello everyone, I’m working on the DG solver of the CHNS (Cahn-Hilliard Navier-Stokes) for the multiphase flow. The SIPG is used to treat the diffusion term and an upwind flux scheme is used for the convection term. Now … --- ## [Elasticity problem with radially symmetric traction function on a circle on a face](https://fenicsproject.discourse.group/t/elasticity-problem-with-radially-symmetric-traction-function-on-a-circle-on-a-face/19733)
**Author:** [@alex24](https://fenicsproject.discourse.group/u/alex24)\ **Replies:** 1\ **Last updated:** [June 12, 2026, 10:31am UTC](https://fenicsproject.discourse.group/t/elasticity-problem-with-radially-symmetric-traction-function-on-a-circle-on-a-face/19733 "2026-06-12T10:31:27Z")
Hi, I would like to load a rectangle with a traction boundary condition on a face normal to the x axis. The traction is applied on a circle in that face, and the traction follows a radially symmetric function, that is p… --- ## [Fixing dofs normal to direction vector used in traction boundary condition for linear elasticity](https://fenicsproject.discourse.group/t/fixing-dofs-normal-to-direction-vector-used-in-traction-boundary-condition-for-linear-elasticity/19726)
**Author:** [@alex24](https://fenicsproject.discourse.group/u/alex24)\ **Replies:** 6\ **Last updated:** [June 8, 2026, 3:59pm UTC](https://fenicsproject.discourse.group/t/fixing-dofs-normal-to-direction-vector-used-in-traction-boundary-condition-for-linear-elasticity/19726 "2026-06-08T15:59:01Z")
Hi, I would like to partially fix the dofs where a traction force is applied on a circle on the surface of a body. Right now the way I am applying the traction is the following: # Traction direction: push along +x (cha… --- ## [How to compute maximum stresses in elstic solver outside of sphere and not in nodes belonging to low quality elements](https://fenicsproject.discourse.group/t/how-to-compute-maximum-stresses-in-elstic-solver-outside-of-sphere-and-not-in-nodes-belonging-to-low-quality-elements/19723)
**Author:** [@alex24](https://fenicsproject.discourse.group/u/alex24)\ **Replies:** 3\ **Last updated:** [June 4, 2026, 11:05am UTC](https://fenicsproject.discourse.group/t/how-to-compute-maximum-stresses-in-elstic-solver-outside-of-sphere-and-not-in-nodes-belonging-to-low-quality-elements/19723 "2026-06-04T11:05:38Z")
Hi, I would like to compute the highest maximum principal stress outside of a sphere (specified by function in\_sphere()) and not in nodes belonging to low quality elements. I have a function that can compute the element… --- ## [Applying Jacobian-Free Newton-Krylov methods in FeniCS](https://fenicsproject.discourse.group/t/applying-jacobian-free-newton-krylov-methods-in-fenics/19725)
**Author:** [@M\_Jalili](https://fenicsproject.discourse.group/u/M_Jalili)\ **Replies:** 2\ **Last updated:** [June 4, 2026, 7:56am UTC](https://fenicsproject.discourse.group/t/applying-jacobian-free-newton-krylov-methods-in-fenics/19725 "2026-06-04T07:56:50Z")
Dear. Researchers I am solving a multiphysics problem using legacy fenics. Due to the ill-conditioning of Jacobain, I intend to utilize Jacobian-Free Newton-Krylov method for treating systems of nonlinear equations. How… --- ## [Elastic solver code layout improvements and displacement at required node](https://fenicsproject.discourse.group/t/elastic-solver-code-layout-improvements-and-displacement-at-required-node/19716)
**Author:** [@alex24](https://fenicsproject.discourse.group/u/alex24)\ **Replies:** 4\ **Last updated:** [June 2, 2026, 8:06pm UTC](https://fenicsproject.discourse.group/t/elastic-solver-code-layout-improvements-and-displacement-at-required-node/19716 "2026-06-02T20:06:20Z")
Hi, I wrote the following simple code to solve for linear elasticity and to compute the maximum principal stress. The displacement elements are linear and the computed stresses are interpolated to a DG 0 space. My fi… --- ## [Errors while running asimov-contact demos](https://fenicsproject.discourse.group/t/errors-while-running-asimov-contact-demos/19663)
**Author:** [@kumar](https://fenicsproject.discourse.group/u/kumar)\ **Replies:** 8\ **Last updated:** [May 27, 2026, 6:36pm UTC](https://fenicsproject.discourse.group/t/errors-while-running-asimov-contact-demos/19663 "2026-05-27T18:36:18Z")
Hello everyone, I have installed dolfinx\_contact and can build it successfully, but I run into an error when executing the demo scripts (e.g. demo\_friction\_cylinders.py). The issue seems similar to the one discussed her… --- ## [Solving the compressible flow problem on curved domain](https://fenicsproject.discourse.group/t/solving-the-compressible-flow-problem-on-curved-domain/19715)
**Author:** [@Dainy](https://fenicsproject.discourse.group/u/Dainy)\ **Replies:** 1\ **Last updated:** [May 26, 2026, 8:56am UTC](https://fenicsproject.discourse.group/t/solving-the-compressible-flow-problem-on-curved-domain/19715 "2026-05-26T08:56:29Z")
Hello, everyone. Recently, I have been solving the compressible NS equations on the unit disk, with the model as follows: where, J =E + u \\times B. and The numerical scheme is： When solving this equation, t… [Next page](https://fenicsproject.discourse.group/c/general/14.md?page=1)