# General Discussion **URL:** https://community.freefem.org/c/general-discussion/7.md?page=14 [Latest](https://community.freefem.org/latest.md) · [Categories](https://community.freefem.org/categories.md) **Page:** 15 --- ## [Hyperelastic laws for 3d](https://community.freefem.org/t/hyperelastic-laws-for-3d/3584)
**Author:** [@koenvantuijl](https://community.freefem.org/u/koenvantuijl)\ **Replies:** 0\ **Last updated:** [November 16, 2024, 2:05pm UTC](https://community.freefem.org/t/hyperelastic-laws-for-3d/3584 "2024-11-16T14:05:58Z")
Hello, I have attempted to rewrite the hyperelastic macros given ElasticLaw2d.idp file into 3d version. But thus far I cant get any results from it in both static as dynamic problems. Can anyone give me some pointers i… --- ## [Moving domain problem](https://community.freefem.org/t/moving-domain-problem/3575)
**Author:** [@goutham2023](https://community.freefem.org/u/goutham2023)\ **Replies:** 3\ **Last updated:** [November 13, 2024, 11:29am UTC](https://community.freefem.org/t/moving-domain-problem/3575 "2024-11-13T11:29:37Z")
Hello everyone, I’m working on a simulation where a material surface is undergoing ablation (material is being “burned” or removed) over time, which causes the surface to shrink. In FreeFem++, I need to do the followin… --- ## [Heat Flux Boundary Condition for 1D Line Element](https://community.freefem.org/t/heat-flux-boundary-condition-for-1d-line-element/3568)
**Author:** [@goutham2023](https://community.freefem.org/u/goutham2023)\ **Replies:** 3\ **Last updated:** [November 12, 2024, 9:06pm UTC](https://community.freefem.org/t/heat-flux-boundary-condition-for-1d-line-element/3568 "2024-11-12T21:06:41Z")
Hello everyone, I have a question regarding boundary conditions in FreeFEM++. Specifically, I would like to know if it is possible to apply a heat flux boundary condition to a one-dimensional line element at any of its … --- ## [Pseudo Inverse of singular matrix](https://community.freefem.org/t/pseudo-inverse-of-singular-matrix/230)
**Author:** [@hraf5](https://community.freefem.org/u/hraf5)\ **Replies:** 5\ **Last updated:** [November 10, 2024, 8:56am UTC](https://community.freefem.org/t/pseudo-inverse-of-singular-matrix/230 "2024-11-10T08:56:43Z")
Hello every one, How to calculate the pseudoInverse of a singular matrix with FreeFem++? Best regards. --- ## [Request for help on DDM method for handling vector fields](https://community.freefem.org/t/request-for-help-on-ddm-method-for-handling-vector-fields/3566)
**Author:** [@qingYang](https://community.freefem.org/u/qingYang)\ **Replies:** 13\ **Last updated:** [November 6, 2024, 11:20pm UTC](https://community.freefem.org/t/request-for-help-on-ddm-method-for-handling-vector-fields/3566 "2024-11-06T23:20:44Z")
Dear Professor and FreeFem users: I want to use the DDM method to solve three-dimensional electromagnetic field problems. Before solving, some preprocessing is needed, such as adding layers and smoothing (as shown in th… --- ## [Location Matrix with vectorial space](https://community.freefem.org/t/location-matrix-with-vectorial-space/3572)
**Author:** [@larismartins](https://community.freefem.org/u/larismartins)\ **Replies:** 0\ **Last updated:** [November 4, 2024, 1:58pm UTC](https://community.freefem.org/t/location-matrix-with-vectorial-space/3572 "2024-11-04T13:58:53Z")
Hello, I’m trying to build a location matrix for a FE vectorial space. Am I doing it right like this? fespace LambdaH(calP, \[Pm, Pm\]); LambdaH \[l10, l20\]; LambdaH \[l1X, l2X\] = \[x,x\], \[l1Y, l2Y\] = \[y,y\]; int nDoFl0 = L… --- ## [Large scale FSI example with parallel implementation](https://community.freefem.org/t/large-scale-fsi-example-with-parallel-implementation/3460)
**Author:** [@clthu](https://community.freefem.org/u/clthu)\ **Replies:** 13\ **Last updated:** [November 1, 2024, 6:13am UTC](https://community.freefem.org/t/large-scale-fsi-example-with-parallel-implementation/3460 "2024-11-01T06:13:48Z")
Hi, everyone. Nowadays I am doing some simulation of fluid-structure interaction. Actually, I know how to assemble the matrix for fluid, solid and its coupling part. I also know how to write a parallel code for decoupl… --- ## [How to use RT03d finite elements?](https://community.freefem.org/t/how-to-use-rt03d-finite-elements/3569)
**Author:** [@yowie](https://community.freefem.org/u/yowie)\ **Replies:** 5\ **Last updated:** [October 31, 2024, 3:31pm UTC](https://community.freefem.org/t/how-to-use-rt03d-finite-elements/3569 "2024-10-31T15:31:22Z")
Hey y’all! As prep for my master’s thesis, I’m trying to implement a numerical method for the heat equation using Raviart-Thomas finite elements. While the documentation has a nice example on how to use RT0 finite eleme… --- ## [Include paths : which order?](https://community.freefem.org/t/include-paths-which-order/967)
**Author:** [@david.fabre](https://community.freefem.org/u/david.fabre)\ **Replies:** 1\ **Last updated:** [October 28, 2024, 2:02pm UTC](https://community.freefem.org/t/include-paths-which-order/967 "2024-10-28T14:02:03Z")
Hello all ! One question about how paths are handled in “include” statements. My freefem++.pref file contains this : includepath += “./” includepath += “/Users/fabred/StabFem\_DEVELOP/StabFem/SOURCES\_FREEFEM/INCLUDE/” … --- ## [SegFaults on examples](https://community.freefem.org/t/segfaults-on-examples/3567)
**Author:** [@Giuseppe](https://community.freefem.org/u/Giuseppe)\ **Replies:** 0\ **Last updated:** [October 28, 2024, 10:11am UTC](https://community.freefem.org/t/segfaults-on-examples/3567 "2024-10-28T10:11:15Z")
Dear FreeFem community, I have just installed FreeFem from the Dependency management when building from source is not quite perfect. · Issue #318 · FreeFem/FreeFem-sources · GitHub , as I had troubles following the offi… --- ## [Operator error of exp function](https://community.freefem.org/t/operator-error-of-exp-function/3564)
**Author:** [@Zucker](https://community.freefem.org/u/Zucker)\ **Replies:** 0\ **Last updated:** [October 27, 2024, 9:03am UTC](https://community.freefem.org/t/operator-error-of-exp-function/3564 "2024-10-27T09:03:49Z")
hello I’m trying to write weak formulation for PDE system and I can’t use the function exp for the result u(x,y) and I get the error operator error . I will be glad to get some help. --- ## [High Voltage Industry Use Cases](https://community.freefem.org/t/high-voltage-industry-use-cases/3563)
**Author:** [@jleman](https://community.freefem.org/u/jleman)\ **Replies:** 0\ **Last updated:** [October 26, 2024, 3:45pm UTC](https://community.freefem.org/t/high-voltage-industry-use-cases/3563 "2024-10-26T15:45:59Z")
I am a past user of finite element software in the power industry (generally quasi-electrostatic simulation). I had primarily used high-end commercial codes but am looking for an alternative. I found FreeFEM online. It s… --- ## [Strange pressure when solving navier stokes using newton iteration](https://community.freefem.org/t/strange-pressure-when-solving-navier-stokes-using-newton-iteration/3560)
**Author:** [@localhost](https://community.freefem.org/u/localhost)\ **Replies:** 8\ **Last updated:** [October 26, 2024, 11:31am UTC](https://community.freefem.org/t/strange-pressure-when-solving-navier-stokes-using-newton-iteration/3560 "2024-10-26T11:31:06Z")
I solve navier stokes problem using newton method. I used the code from (FreeFem++ users | Main \>\> Newton1) I changed the code into transient problem as follows: load "iovtk" real h=0.04; real L=3.2; real H=5\*h; real l… --- ## [Parameterized macro?](https://community.freefem.org/t/parameterized-macro/3135)
**Author:** [@bcaval](https://community.freefem.org/u/bcaval)\ **Replies:** 7\ **Last updated:** [October 25, 2024, 10:45am UTC](https://community.freefem.org/t/parameterized-macro/3135 "2024-10-25T10:45:32Z")
Hello FreeFem community, Is it possible to define a parameterized macro with a parameter inside in order to use it in varf. In fact, this parameter could be the index of region. For example : real \[int, int\]\[int\] c(10… --- ## [Using levelset to integrate a fespace variable in a subregion of the mesh](https://community.freefem.org/t/using-levelset-to-integrate-a-fespace-variable-in-a-subregion-of-the-mesh/3561)
**Author:** [@Christian](https://community.freefem.org/u/Christian)\ **Replies:** 1\ **Last updated:** [October 24, 2024, 9:31am UTC](https://community.freefem.org/t/using-levelset-to-integrate-a-fespace-variable-in-a-subregion-of-the-mesh/3561 "2024-10-24T09:31:29Z")
Hi there! I was wondering if it is possible to integrate a FESpace variable over a subregion of the original mesh. Let’s suppose Th3D in my example is a cylinder with a height of 0.0 to 100 cm. I want to integrate the P… --- ## [Jump boundary condition (discontinous galerkin)](https://community.freefem.org/t/jump-boundary-condition-discontinous-galerkin/2073)
**Author:** [@RodZ](https://community.freefem.org/u/RodZ)\ **Replies:** 4\ **Last updated:** [October 23, 2024, 12:52pm UTC](https://community.freefem.org/t/jump-boundary-condition-discontinous-galerkin/2073 "2024-10-23T12:52:40Z")
Hi everyone, I would like to implement the following variational problem: \\begin{cases} -div(A\_i \\nabla u\_i) = f \\text{ in } \\Omega\_i \\\\ (A\_1 \\nabla u\_1) \\cdot n = (A\_2 \\nabla u\_2) \\cdot n \\text{ on } \\Gamma = \\partia… --- ## [Non homogeneous boundary and initial conditions](https://community.freefem.org/t/non-homogeneous-boundary-and-initial-conditions/154)
**Author:** [@Aicha](https://community.freefem.org/u/Aicha)\ **Replies:** 50\ **Last updated:** [October 23, 2024, 2:03am UTC](https://community.freefem.org/t/non-homogeneous-boundary-and-initial-conditions/154 "2024-10-23T02:03:52Z")
Hi, i try to write a code who calculate the solution of the problem: \\partial\_t u + u \\partial\_x u - \\nu \\partial^2\_x u =1+x, \\ x \\in \[0,1\], t \\in \[0,1\] with initial condition: u(x,0)= -4 \\nu \\dfrac{x+3/2}{ (x+3/2… --- ## [Nan error when solve Navier-Stokes equations using PETSc](https://community.freefem.org/t/nan-error-when-solve-navier-stokes-equations-using-petsc/1431)
**Author:** [@yhao](https://community.freefem.org/u/yhao)\ **Replies:** 8\ **Last updated:** [October 23, 2024, 2:03am UTC](https://community.freefem.org/t/nan-error-when-solve-navier-stokes-equations-using-petsc/1431 "2024-10-23T02:03:16Z")
Dear all, I am now working on Navier-Stokes equations with PETSc. I am trying to solve the equations in a 125\*100\*100 domain, and build this cube domain mesh by Gmsh. However, when I try to solve it with a higher resolu… --- ## [Incorrect convergence rate for "Element\_P4" in 2d](https://community.freefem.org/t/incorrect-convergence-rate-for-element-p4-in-2d/1400)
**Author:** [@Newhat](https://community.freefem.org/u/Newhat)\ **Replies:** 4\ **Last updated:** [October 22, 2024, 2:18pm UTC](https://community.freefem.org/t/incorrect-convergence-rate-for-element-p4-in-2d/1400 "2024-10-22T14:18:49Z")
load "Element\_P3" load "Element\_P4" int k = 1\*2\*2; mesh Th = square(10\*k, 10\*k); //plot(Th); func Pk = P4; fespace Vhc ( Th, Pk ); Vhc uc,ucX,ucY,fC,fCh,ucEX,err; //--exact solution, partial derivatives and rhs---- ucE… --- ## [The parallel solution of the 3D heat conduction equation using PETSc results in errors](https://community.freefem.org/t/the-parallel-solution-of-the-3d-heat-conduction-equation-using-petsc-results-in-errors/3555)
**Author:** [@yongheng](https://community.freefem.org/u/yongheng)\ **Replies:** 9\ **Last updated:** [October 22, 2024, 9:39am UTC](https://community.freefem.org/t/the-parallel-solution-of-the-3d-heat-conduction-equation-using-petsc-results-in-errors/3555 "2024-10-22T09:39:27Z")
Hello, I am experiencing issues with obtaining consistent results between serial and parallel computations of the three-dimensional heat conduction equation using PETSc. The first image is my mesh diagram, and the second… --- ## [Combining two meshes](https://community.freefem.org/t/combining-two-meshes/881)
**Author:** [@zese](https://community.freefem.org/u/zese)\ **Replies:** 1\ **Last updated:** [October 21, 2024, 5:02am UTC](https://community.freefem.org/t/combining-two-meshes/881 "2024-10-21T05:02:05Z")
Dear all I want to have two regions and then combine them into 1 region (th=th1+th2) because some integrals are solved on th and some on th1. so I made the mesh as follow: real xr=6., lsponge=60., Xmax1=100., yr=3., ys… --- ## [Integrating Multiple Meshes](https://community.freefem.org/t/integrating-multiple-meshes/2914)
**Author:** [@YOuungLi](https://community.freefem.org/u/YOuungLi)\ **Replies:** 2\ **Last updated:** [October 21, 2024, 4:57am UTC](https://community.freefem.org/t/integrating-multiple-meshes/2914 "2024-10-21T04:57:22Z")
Dear All, I’m encountering an error while attempting to combine multiple meshes, and I’m having trouble understanding why this error persists even after adjusting the orientation. error : “Bug in mortar constrution : c… --- ## [Mesh, tangent boundaries](https://community.freefem.org/t/mesh-tangent-boundaries/3551)
**Author:** [@pi.3.141etc](https://community.freefem.org/u/pi.3.141etc)\ **Replies:** 0\ **Last updated:** [October 17, 2024, 11:27am UTC](https://community.freefem.org/t/mesh-tangent-boundaries/3551 "2024-10-17T11:27:03Z")
Hello Freefem community, I am experimenting with the mesh script with two disks D1=B(0,r1), D2=B((r1/2,0), r2), as in https://doc.freefem.org/documentation/mesh-generation.html, in the case when the boundaries of D1, D… --- ## [Error convergence on Stokes problem](https://community.freefem.org/t/error-convergence-on-stokes-problem/3550)
**Author:** [@ggeedorah](https://community.freefem.org/u/ggeedorah)\ **Replies:** 1\ **Last updated:** [October 17, 2024, 8:58am UTC](https://community.freefem.org/t/error-convergence-on-stokes-problem/3550 "2024-10-17T08:58:58Z")
Hi, i’m trying to implement a code for a Stokes problem, but there is two things that i’m having trouble. First of all is the introduction of the quotient space L\_0^2(\\Omega) via Lagrange Multipliers, I tried the followi… --- ## [Integration over a subset of meshL](https://community.freefem.org/t/integration-over-a-subset-of-meshl/3549)
**Author:** [@mhg](https://community.freefem.org/u/mhg)\ **Replies:** 0\ **Last updated:** [October 16, 2024, 8:03am UTC](https://community.freefem.org/t/integration-over-a-subset-of-meshl/3549 "2024-10-16T08:03:31Z")
load "msh3" int nx = 10; meshL ThLarge = segment(nx,\[2\*x,0.,0.\],removeduplicate=true); meshL Th = trunc(ThLarge,x\<1,cleanmesh=true); fespace Vh(ThLarge, P2); varf testvarf(cf,testcf) = int1d(Th)(testcf); real\[int\] rhs… --- ## [Boundary issues for sphere](https://community.freefem.org/t/boundary-issues-for-sphere/3547)
**Author:** [@mamun0954](https://community.freefem.org/u/mamun0954)\ **Replies:** 0\ **Last updated:** [October 15, 2024, 2:56am UTC](https://community.freefem.org/t/boundary-issues-for-sphere/3547 "2024-10-15T02:56:51Z")
Hello everyone Good morning. I want to make a 3D boundary-like sphere with two plane sections. I can easily make a sphere, but I cannot make it with two plane sections, as given in the following figure. Actually, I want… --- ## [Vectorial PDE, conditions, stiffness matrix](https://community.freefem.org/t/vectorial-pde-conditions-stiffness-matrix/3543)
**Author:** [@pi.3.141etc](https://community.freefem.org/u/pi.3.141etc)\ **Replies:** 5\ **Last updated:** [October 14, 2024, 10:56am UTC](https://community.freefem.org/t/vectorial-pde-conditions-stiffness-matrix/3543 "2024-10-14T10:56:42Z")
Hello FreeFem community, I am looking for how to impose conditions in vectorial PDE problems. More preciesely, I am working on a NS problem. Assuming my variables are \[u,v,p\], in a domain, say \[0,2\]x\[0,1\], I look for … --- ## [MESH ERROR with semi circle heaters on 888](https://community.freefem.org/t/mesh-error-with-semi-circle-heaters-on-888/3545)
**Author:** [@MNSFREEFEM](https://community.freefem.org/u/MNSFREEFEM)\ **Replies:** 0\ **Last updated:** [October 14, 2024, 8:52am UTC](https://community.freefem.org/t/mesh-error-with-semi-circle-heaters-on-888/3545 "2024-10-14T08:52:18Z")
Hi everyone, i have got an issue regarding making a rectangular shape geometry with two semi circular heaters beneath it ,but unfortunately mesh is generated inside semi circle as well ,how can i remove this issue --- ## [Program running](https://community.freefem.org/t/program-running/3526)
**Author:** [@mamun0954](https://community.freefem.org/u/mamun0954)\ **Replies:** 12\ **Last updated:** [October 11, 2024, 7:48am UTC](https://community.freefem.org/t/program-running/3526 "2024-10-11T07:48:23Z")
Hello everyone Good afternoon. I am new in freefem++, so I cannot run this in freefem++. Can anyone help to correct my program. Thanks in advance. // Parameters real r = 1; // Cylinder radius real h = 2; … --- ## [Error with the Freefem script; composite finite element spaces](https://community.freefem.org/t/error-with-the-freefem-script-composite-finite-element-spaces/3541)
**Author:** [@pi.3.141etc](https://community.freefem.org/u/pi.3.141etc)\ **Replies:** 5\ **Last updated:** [October 10, 2024, 5:33pm UTC](https://community.freefem.org/t/error-with-the-freefem-script-composite-finite-element-spaces/3541 "2024-10-10T17:33:17Z")
Hello, I am experimenting with a Freefem script, which demonstrates the composite finite element spaces, as in the example solving Stokes equations given at Composite finite element spaces NEW!. The script runs proper… [Previous page](https://community.freefem.org/c/general-discussion/7.md?page=13) [Next page](https://community.freefem.org/c/general-discussion/7.md?page=15)