# General Discussion **URL:** https://community.freefem.org/c/general-discussion/7.md?page=60 [Latest](https://community.freefem.org/latest.md) · [Categories](https://community.freefem.org/categories.md) **Page:** 61 --- ## [Unsteady three dimensional PETSc](https://community.freefem.org/t/unsteady-three-dimensional-petsc/992)
**Author:** [@Robert](https://community.freefem.org/u/Robert)\ **Replies:** 6\ **Last updated:** [May 27, 2021, 8:58pm UTC](https://community.freefem.org/t/unsteady-three-dimensional-petsc/992 "2021-05-27T20:58:53Z")
Hello everyone, I am trying to solve a simple case, of a 3D laminar flow inside a pipe using PETSc, on FreeFEM++ v4.8. This is a part of the code used (I removed only the part with saving files): \> load "PETSc" \> macro… --- ## [Freefem has stopped working](https://community.freefem.org/t/freefem-has-stopped-working/996)
**Author:** [@chaimaa](https://community.freefem.org/u/chaimaa)\ **Replies:** 0\ **Last updated:** [May 26, 2021, 11:02am UTC](https://community.freefem.org/t/freefem-has-stopped-working/996 "2021-05-26T11:02:50Z")
hello, When I run my code, I get this message : freefem has stopped working. the same code is working completely fine for other geometries imported from the same cad tool .Does anyone know what could be the reason? --- ## [Edge label changed after adaptmesh](https://community.freefem.org/t/edge-label-changed-after-adaptmesh/995)
**Author:** [@HayoungChung](https://community.freefem.org/u/HayoungChung)\ **Replies:** 0\ **Last updated:** [May 26, 2021, 11:02am UTC](https://community.freefem.org/t/edge-label-changed-after-adaptmesh/995 "2021-05-26T11:02:23Z")
Dear all, Can anyone please comment on changing labels of the vertices on the edge after adaptmesh()? And suggestions to fixate the newly created vertices would be greatly appreciated, if possible. border m1(t=-0., 1)… --- ## [Euqiry about the interpolation in FreeFEM](https://community.freefem.org/t/euqiry-about-the-interpolation-in-freefem/994)
**Author:** [@ligax](https://community.freefem.org/u/ligax)\ **Replies:** 0\ **Last updated:** [May 26, 2021, 4:08am UTC](https://community.freefem.org/t/euqiry-about-the-interpolation-in-freefem/994 "2021-05-26T04:08:25Z")
Dear all, I meet some problems on interpolation. The following is the code: solve LP(w,v)= int2d(V1)(dx(w)\*dx(v)+dy(w)\*dy(v)) +int2d(V1)(dx(u2)\*dx(v)\*Xi+dy(u2)\*dy(v)\*Xi +dx(u2)\*v\*dx(Xi)+dy(u2)\*v\*dy(Xi)) Here w,v a… --- ## [Different result of the same problem using different meshes](https://community.freefem.org/t/different-result-of-the-same-problem-using-different-meshes/993)
**Author:** [@marcodeba](https://community.freefem.org/u/marcodeba)\ **Replies:** 0\ **Last updated:** [May 25, 2021, 4:55pm UTC](https://community.freefem.org/t/different-result-of-the-same-problem-using-different-meshes/993 "2021-05-25T16:55:16Z")
meshEDDY.zip (3.5 MB) eddyGMSH.zip (2.4 MB) Hi everybody! I have developed in the past times a code that solves eddy current problems with freefem++ (MUMPS solver). Solving for meshes directly developed in FF++ I can … --- ## [TetGen for domains with overlapping facets](https://community.freefem.org/t/tetgen-for-domains-with-overlapping-facets/989)
**Author:** [@fotios.kasolis](https://community.freefem.org/u/fotios.kasolis)\ **Replies:** 1\ **Last updated:** [May 21, 2021, 8:53am UTC](https://community.freefem.org/t/tetgen-for-domains-with-overlapping-facets/989 "2021-05-21T08:53:41Z")
Dear FreeFEM comminity, Is there any example or does anybody know how to mesh, provided feasibility, a domain like the one in the attached code? The problem here is that the subdomain is not strictly contained in the bo… --- ## [1D boundary periodic conditions](https://community.freefem.org/t/1d-boundary-periodic-conditions/983)
**Author:** [@simonenatipoltri](https://community.freefem.org/u/simonenatipoltri)\ **Replies:** 1\ **Last updated:** [May 18, 2021, 4:20pm UTC](https://community.freefem.org/t/1d-boundary-periodic-conditions/983 "2021-05-18T16:20:18Z")
Hi there! I’m working on a code modeling a 2D-1D coupling. I don’t have any problem in imposing 2D periodic boundary conditions, but I do in imposing 1D ones. The variable is c(x) in (0,1) and the boundary condition to … --- ## [Problem reading gmsh mesh in FreeFem](https://community.freefem.org/t/problem-reading-gmsh-mesh-in-freefem/982)
**Author:** [@marcodeba](https://community.freefem.org/u/marcodeba)\ **Replies:** 0\ **Last updated:** [May 18, 2021, 8:26am UTC](https://community.freefem.org/t/problem-reading-gmsh-mesh-in-freefem/982 "2021-05-18T08:26:27Z")
Dear FreeFem++ developers and users, I’m wrtiting to you since I have encountered an issue in the loading of a mesh produced with the software gmsh in my freefem code. I commonly use this software and I have never encou… --- ## [Accessing matrix elements](https://community.freefem.org/t/accessing-matrix-elements/981)
**Author:** [@amtravco](https://community.freefem.org/u/amtravco)\ **Replies:** 1\ **Last updated:** [May 18, 2021, 12:02am UTC](https://community.freefem.org/t/accessing-matrix-elements/981 "2021-05-18T00:02:58Z")
Two simple questions. Suppose I have a matrix created as matrix C = \[\[1, 2, 3\], \[2, 4, 0\], \[8, 1, 9\]\]; How can I access individual elements of this matrix? I have tried the obvious C\[1\]\[2\] = 5 but this syntax is not… --- ## [A nonlinear problem](https://community.freefem.org/t/a-nonlinear-problem/980)
**Author:** [@fem-naive](https://community.freefem.org/u/fem-naive)\ **Replies:** 0\ **Last updated:** [May 15, 2021, 8:45pm UTC](https://community.freefem.org/t/a-nonlinear-problem/980 "2021-05-15T20:45:44Z")
Hello I am a beginner of FreeFem. I am studying how to solve nonlinear problems and make codes. In reference to the examples provided by the FREEFEM guidebook, I am trying to use the Newton method. My problem is f= -… --- ## [Boundary element method](https://community.freefem.org/t/boundary-element-method/977)
**Author:** [@Daoudi](https://community.freefem.org/u/Daoudi)\ **Replies:** 2\ **Last updated:** [May 15, 2021, 9:03am UTC](https://community.freefem.org/t/boundary-element-method/977 "2021-05-15T09:03:26Z")
Hello everyone, How can I use the boundary element method in freefem Thanks --- ## [About define the the border lines of 3D cuboid plate divided by Tetgen](https://community.freefem.org/t/about-define-the-the-border-lines-of-3d-cuboid-plate-divided-by-tetgen/979)
**Author:** [@HGH](https://community.freefem.org/u/HGH)\ **Replies:** 0\ **Last updated:** [May 15, 2021, 5:10am UTC](https://community.freefem.org/t/about-define-the-the-border-lines-of-3d-cuboid-plate-divided-by-tetgen/979 "2021-05-15T05:10:30Z")
Hello, guys Who know how to define the the border lines of 3D cuboid plate divided by Tetgen ? I mean I need PDF for vibration, and border lines for Dirichlet condition, but it looks like only face can be defined in 3D … --- ## [Derivative and integration of physical variable over Boundary](https://community.freefem.org/t/derivative-and-integration-of-physical-variable-over-boundary/976)
**Author:** [@sumantkr](https://community.freefem.org/u/sumantkr)\ **Replies:** 4\ **Last updated:** [May 14, 2021, 4:14pm UTC](https://community.freefem.org/t/derivative-and-integration-of-physical-variable-over-boundary/976 "2021-05-14T16:14:07Z")
Dear all, I am trying to compute the heat flux and cumulative heat flux over a boundary section of the square. I have tried with writing the code as : flux = int1d(Th, 4)(-dx(T)\*N.x) but each time I am gett… --- ## [Import 3D Geometry/Mesh](https://community.freefem.org/t/import-3d-geometry-mesh/969)
**Author:** [@Robert](https://community.freefem.org/u/Robert)\ **Replies:** 4\ **Last updated:** [May 13, 2021, 10:28am UTC](https://community.freefem.org/t/import-3d-geometry-mesh/969 "2021-05-13T10:28:43Z")
Hello everyone, Although there are a lot of topics on this subject I have a few questions about 3D files. I am using Salome to create a geometry and its module “SMESH” to create meshes with tetra elements. So far, I man… --- ## [The ECCOMAS 2021 videos are on the FreeFEM Youtube channel](https://community.freefem.org/t/the-eccomas-2021-videos-are-on-the-freefem-youtube-channel/973)
**Author:** [@franck.lahaye](https://community.freefem.org/u/franck.lahaye)\ **Replies:** 0\ **Last updated:** [May 12, 2021, 4:58pm UTC](https://community.freefem.org/t/the-eccomas-2021-videos-are-on-the-freefem-youtube-channel/973 "2021-05-12T16:58:09Z")
Have a look here : https://www.youtube.com/channel/UCJlw6LHQt7UWXrH2uzGYZWw/videos --- ## [Algorithm of KMF](https://community.freefem.org/t/algorithm-of-kmf/970)
**Author:** [@Daoudi](https://community.freefem.org/u/Daoudi)\ **Replies:** 0\ **Last updated:** [May 12, 2021, 12:12pm UTC](https://community.freefem.org/t/algorithm-of-kmf/970 "2021-05-12T12:12:30Z")
Hello There’s some one can help me for programming the KMF algorithm for solving an Inverse problem. --- ## [Naive Publishing Code for FreeFEM++](https://community.freefem.org/t/naive-publishing-code-for-freefem/98)
**Author:** [@fotios.kasolis](https://community.freefem.org/u/fotios.kasolis)\ **Replies:** 1\ **Last updated:** [May 9, 2021, 9:59pm UTC](https://community.freefem.org/t/naive-publishing-code-for-freefem/98 "2021-05-09T21:59:34Z")
Dear ffpp community, Here, I attach an idp file that defines macros for generating html reports in ffpp, such that the one that is depicted in the figure. Hope you enjoy and find useful. For the pictures to appear corre… --- ## [Savemesh does not work properly](https://community.freefem.org/t/savemesh-does-not-work-properly/966)
**Author:** [@sgkkr](https://community.freefem.org/u/sgkkr)\ **Replies:** 6\ **Last updated:** [May 8, 2021, 6:08pm UTC](https://community.freefem.org/t/savemesh-does-not-work-properly/966 "2021-05-08T18:08:50Z")
I have several discrete meshes and I join them on Freefem++ using the following command. The mesh is created perfectly and I can plot it. But there is an error while saving the mesh. As a check, I am also able to create … --- ## [External forces in Navier-Stokes equation](https://community.freefem.org/t/external-forces-in-navier-stokes-equation/965)
**Author:** [@yhao](https://community.freefem.org/u/yhao)\ **Replies:** 0\ **Last updated:** [May 7, 2021, 9:24am UTC](https://community.freefem.org/t/external-forces-in-navier-stokes-equation/965 "2021-05-07T09:24:57Z")
Hi, I am trying to solve the Navier-Stokes equations with an external force that is perpendicular to the velocity. Firstly I defined a fespace of it and made function f on the fespace: fespace Fh(Th, P2dc); Fh fu = k\*… --- ## [Usage of mmg3d does not work like in doc](https://community.freefem.org/t/usage-of-mmg3d-does-not-work-like-in-doc/752)
**Author:** [@BeniaminBogosel](https://community.freefem.org/u/BeniaminBogosel)\ **Replies:** 19\ **Last updated:** [May 6, 2021, 11:27am UTC](https://community.freefem.org/t/usage-of-mmg3d-does-not-work-like-in-doc/752 "2021-05-06T11:27:27Z")
Hello, I tried to use mmg3d to adapt some 3d mesh. However, it seems that the examples in the documentation pdf are not up to date. I use version 4.7 of FreeFEM. I tried to use the command Th3 = mmg3d(Th,options=opt); … --- ## [Install pARMS library of parallel solvers](https://community.freefem.org/t/install-parms-library-of-parallel-solvers/480)
**Author:** [@abou](https://community.freefem.org/u/abou)\ **Replies:** 5\ **Last updated:** [May 6, 2021, 5:49am UTC](https://community.freefem.org/t/install-parms-library-of-parallel-solvers/480 "2021-05-06T05:49:40Z")
Hello I’m trying to solve a 3-D heat equation. When I reduce the mesh I get this error: read mesh ok 0Mesh3, num Tetra:= 583101, num Vertice:= 102624 num boundary Triangles:= 64696 Mesh3::meshS, num Triangles:= 64696, … --- ## [SLEPc-Complex eigenmodes](https://community.freefem.org/t/slepc-complex-eigenmodes/913)
**Author:** [@Robert](https://community.freefem.org/u/Robert)\ **Replies:** 21\ **Last updated:** [May 5, 2021, 1:41pm UTC](https://community.freefem.org/t/slepc-complex-eigenmodes/913 "2021-05-05T13:41:48Z")
Hello forum, I am using FreeFEM++ 4.8 on Windows 10. Lately, I’ve tried several eigenvalue problems in parallel using SLEPc-complex and I have a few questions. Is there some sort of value scaling in SLEPc when it come… --- ## [Simple problem gives "Error umfpack\_di\_solve status -3"](https://community.freefem.org/t/simple-problem-gives-error-umfpack-di-solve-status-3/962)
**Author:** [@felric](https://community.freefem.org/u/felric)\ **Replies:** 1\ **Last updated:** [May 5, 2021, 5:33am UTC](https://community.freefem.org/t/simple-problem-gives-error-umfpack-di-solve-status-3/962 "2021-05-05T05:33:48Z")
Dear all, I was able to solve successfully some problems in elasticity in 3D. Mesh is extremely simple (a revolved square, so forming a ring). However, as soon as I increase the number of nodes and elements, I get the… --- ## [Maps of int|real array](https://community.freefem.org/t/maps-of-int-real-array/957)
**Author:** [@mrbenson](https://community.freefem.org/u/mrbenson)\ **Replies:** 5\ **Last updated:** [May 4, 2021, 9:36am UTC](https://community.freefem.org/t/maps-of-int-real-array/957 "2021-05-04T09:36:31Z")
Hello, Do you think possible to extend the language to allow the declaration of maps of array like int\[\]\[string\] or real\[\]\[string\] ? Best regards. --- ## [Continues simulations](https://community.freefem.org/t/continues-simulations/953)
**Author:** [@Dua](https://community.freefem.org/u/Dua)\ **Replies:** 4\ **Last updated:** [May 4, 2021, 1:29am UTC](https://community.freefem.org/t/continues-simulations/953 "2021-05-04T01:29:30Z")
Hello developers, I need to run my freefem code for multiple meshes, so that each time my code read a different mesh and do the simulation for this mesh, then stores the result for every mesh and again repeat it continu… --- ## [Nonlinear thermal problem in parallel](https://community.freefem.org/t/nonlinear-thermal-problem-in-parallel/955)
**Author:** [@Mik](https://community.freefem.org/u/Mik)\ **Replies:** 10\ **Last updated:** [May 3, 2021, 7:13am UTC](https://community.freefem.org/t/nonlinear-thermal-problem-in-parallel/955 "2021-05-03T07:13:41Z")
Dear All, I am trying to incorporate non-linear thermal properties in my heat transfer problem. My current approach with solving through Newton Raphson iteratively is turning out to be computationally costly due to the … --- ## [Gmsh physical tags](https://community.freefem.org/t/gmsh-physical-tags/958)
**Author:** [@mrbenson](https://community.freefem.org/u/mrbenson)\ **Replies:** 1\ **Last updated:** [May 2, 2021, 7:53am UTC](https://community.freefem.org/t/gmsh-physical-tags/958 "2021-05-02T07:53:09Z")
Hi, Is there a way to force gmshload and gmshload3 to use physical tags instead of elementary tag when importaing gmsh files ? Best regards. --- ## [Implementation BDM2](https://community.freefem.org/t/implementation-bdm2/956)
**Author:** [@LIU6925](https://community.freefem.org/u/LIU6925)\ **Replies:** 1\ **Last updated:** [May 2, 2021, 7:50am UTC](https://community.freefem.org/t/implementation-bdm2/956 "2021-05-02T07:50:34Z")
Hi, I saw that in FreeFem there are the mixed element spaces RT1, RT1Ortho, RT2, RT2Ortho, BDM1, BDM1Ortho. I need to use BDM2 for a problem (2D mesh). Has the space BDM2 already been implemented? Thank you in advance … --- ## [Automatic parallel](https://community.freefem.org/t/automatic-parallel/951)
**Author:** [@xiaodizhang29](https://community.freefem.org/u/xiaodizhang29)\ **Replies:** 4\ **Last updated:** [April 28, 2021, 2:55pm UTC](https://community.freefem.org/t/automatic-parallel/951 "2021-04-28T14:55:44Z")
Hello, everyone! Is there some tricks on FreeFEM such that I write codes in serial, but it works in parallel. --- ## [Import 3D volume meshes](https://community.freefem.org/t/import-3d-volume-meshes/945)
**Author:** [@mrbenson](https://community.freefem.org/u/mrbenson)\ **Replies:** 2\ **Last updated:** [April 27, 2021, 9:25am UTC](https://community.freefem.org/t/import-3d-volume-meshes/945 "2021-04-27T09:25:17Z")
Hello, I exported a volume mesh in two different formats and import them : gmsh file format using gmshload3 : it works medit file format using readmesh3 : i have some “badly orienated tet” These two files contain exa… [Previous page](https://community.freefem.org/c/general-discussion/7.md?page=59) [Next page](https://community.freefem.org/c/general-discussion/7.md?page=61)