# General Discussion **URL:** https://community.freefem.org/c/general-discussion/7.md?page=18 [Latest](https://community.freefem.org/latest.md) · [Categories](https://community.freefem.org/categories.md) **Page:** 19 --- ## [Elasticité en 3d](https://community.freefem.org/t/elasticite-en-3d/2519)
**Author:** [@aweni](https://community.freefem.org/u/aweni)\ **Replies:** 1\ **Last updated:** [June 19, 2024, 9:36am UTC](https://community.freefem.org/t/elasticite-en-3d/2519 "2024-06-19T09:36:29Z")
Bonjour à tous J’ai implémenté un code 3d de l’équation de l’élasticité en utilisant la méthode de Newmark . L’objectif est d’évaluer l’erreur entre la solution approchée et la solution exact. Mais ça me signale ceci … --- ## [GMSH 3D and Freefem++](https://community.freefem.org/t/gmsh-3d-and-freefem/3183)
**Author:** [@bcaval](https://community.freefem.org/u/bcaval)\ **Replies:** 5\ **Last updated:** [June 18, 2024, 6:01am UTC](https://community.freefem.org/t/gmsh-3d-and-freefem/3183 "2024-06-18T06:01:31Z")
Dear freefem community, I know GMSH has already been posted, but with the current GMSH and Freefem++ 4.6 (last version on windows), it doesn’t work any more. My geo file is rather simple (just a beam with few elements)… --- ## [Category suggestion for real world applications of FreeFEM](https://community.freefem.org/t/category-suggestion-for-real-world-applications-of-freefem/3320)
**Author:** [@Liamani](https://community.freefem.org/u/Liamani)\ **Replies:** 0\ **Last updated:** [June 18, 2024, 5:00am UTC](https://community.freefem.org/t/category-suggestion-for-real-world-applications-of-freefem/3320 "2024-06-18T05:00:51Z")
Hello everyone, I have a query related real world applications of FreeFEM but I don’t know witch category is good for my query because I am new here. so I have know idea. If anyone know please share with me. It will b… --- ## [Varf and speed of calculations](https://community.freefem.org/t/varf-and-speed-of-calculations/3315)
**Author:** [@bcaval](https://community.freefem.org/u/bcaval)\ **Replies:** 0\ **Last updated:** [June 16, 2024, 1:15pm UTC](https://community.freefem.org/t/varf-and-speed-of-calculations/3315 "2024-06-16T13:15:58Z")
Dear freefem community, For the sake of simplicity and generalization in using many freefem codes, I wonder if it is critical or not to write only one freefem varf with many parameters that could be zero rather than wri… --- ## [Exporting velocity profile](https://community.freefem.org/t/exporting-velocity-profile/1013)
**Author:** [@zese](https://community.freefem.org/u/zese)\ **Replies:** 3\ **Last updated:** [June 13, 2024, 4:34pm UTC](https://community.freefem.org/t/exporting-velocity-profile/1013 "2024-06-13T16:34:53Z")
dear all I want to export inlet velocity profile from freefem to a text file. the profile is related to the inlet (x=0,y) with border label of 1. I wrote as below but it seems that it gives me the wrong values when I co… --- ## [Limitation on broadcasting](https://community.freefem.org/t/limitation-on-broadcasting/3294)
**Author:** [@Quqoniy](https://community.freefem.org/u/Quqoniy)\ **Replies:** 2\ **Last updated:** [June 13, 2024, 3:01pm UTC](https://community.freefem.org/t/limitation-on-broadcasting/3294 "2024-06-13T15:01:57Z")
I wonder is there any size limitations for the date when you broadcast it from one processor to another? Say I have solution mesh size depending on n and corresponding solution u1,u2. For n up to around 140 the … --- ## [Need help regarding simulation](https://community.freefem.org/t/need-help-regarding-simulation/3310)
**Author:** [@Monirul25](https://community.freefem.org/u/Monirul25)\ **Replies:** 7\ **Last updated:** [June 13, 2024, 4:53am UTC](https://community.freefem.org/t/need-help-regarding-simulation/3310 "2024-06-13T04:53:31Z")
I want to get following types of figure of Cahn-Hilliard equation. Can you help me please how to do this kind of things using freefem++. I am facing problem regarding this. I wan to such type of computations. I ne… --- ## [3d elasticity problem](https://community.freefem.org/t/3d-elasticity-problem/3286)
**Author:** [@zoumpou](https://community.freefem.org/u/zoumpou)\ **Replies:** 1\ **Last updated:** [June 12, 2024, 3:25pm UTC](https://community.freefem.org/t/3d-elasticity-problem/3286 "2024-06-12T15:25:35Z")
In my code when i use the type:solve i get results for the displacement but when i try to use varf in my problem the displecements are 0. Also i get a different result in the plotting of the movemesh although in the seco… --- ## [Parabolic equation](https://community.freefem.org/t/parabolic-equation/3304)
**Author:** [@doublehai](https://community.freefem.org/u/doublehai)\ **Replies:** 2\ **Last updated:** [June 12, 2024, 10:19am UTC](https://community.freefem.org/t/parabolic-equation/3304 "2024-06-12T10:19:21Z")
Dear all, I am a beginner in finite element methods, and I am using FreeFem++ to solve parabolic equations. However, I have encountered a problem: as I refine the mesh, the error in my calculation results actually incre… --- ## [Change the palette when viewing via "medit"](https://community.freefem.org/t/change-the-palette-when-viewing-via-medit/3300)
**Author:** [@Anis](https://community.freefem.org/u/Anis)\ **Replies:** 1\ **Last updated:** [June 12, 2024, 8:10am UTC](https://community.freefem.org/t/change-the-palette-when-viewing-via-medit/3300 "2024-06-12T08:10:51Z")
Hello, After saving the solutions, I need to view them via medit in a terminal window. In order to compare the solutions, I would have to set the same palette for all solutions. Do you know of a command or option that … --- ## [Compressible Navier-Stokes equations](https://community.freefem.org/t/compressible-navier-stokes-equations/3084)
**Author:** [@syq129](https://community.freefem.org/u/syq129)\ **Replies:** 9\ **Last updated:** [June 11, 2024, 7:51am UTC](https://community.freefem.org/t/compressible-navier-stokes-equations/3084 "2024-06-11T07:51:42Z")
Dear all, I am looking for an or more examples of FreeFEM codes for solving the complete time-dependent compressible Navier-Stokes equations. Many thanks. Regards. --- ## [Diffrence in results between varf and problem statment](https://community.freefem.org/t/diffrence-in-results-between-varf-and-problem-statment/3288)
**Author:** [@Walid](https://community.freefem.org/u/Walid)\ **Replies:** 9\ **Last updated:** [June 10, 2024, 5:16pm UTC](https://community.freefem.org/t/diffrence-in-results-between-varf-and-problem-statment/3288 "2024-06-10T17:16:32Z")
I am tryin to solve PDE and need to use PETSc and need yo know if using it with problem statement or should I use varf statement. the problem is when I use varf statement the results differs than using problem statement… --- ## [Add time data saved in vtk format](https://community.freefem.org/t/add-time-data-saved-in-vtk-format/3296)
**Author:** [@lee-maximee](https://community.freefem.org/u/lee-maximee)\ **Replies:** 1\ **Last updated:** [June 8, 2024, 5:34pm UTC](https://community.freefem.org/t/add-time-data-saved-in-vtk-format/3296 "2024-06-08T17:34:57Z")
I am solving a time-dependent fluid mechanics problem. I want to store the velocity vector field, the pressure and the time date. Then, I want to vizualize the results with Paraview. Here is my attempt: // (u,v) is the… --- ## [Compilation error in the definition of a problem](https://community.freefem.org/t/compilation-error-in-the-definition-of-a-problem/3292)
**Author:** [@lee-maximee](https://community.freefem.org/u/lee-maximee)\ **Replies:** 2\ **Last updated:** [June 8, 2024, 2:46pm UTC](https://community.freefem.org/t/compilation-error-in-the-definition-of-a-problem/3292 "2024-06-08T14:46:59Z")
I want to simulate a von Karman vortex past a cylinder. I get the following error when defining the Navier-Stokes problem: Error line number 87, in file karman-vortices.edp, before token + 79 : ////----------------… --- ## [FreeFem++ petsc ubuntu](https://community.freefem.org/t/freefem-petsc-ubuntu/3289)
**Author:** [@LXX](https://community.freefem.org/u/LXX)\ **Replies:** 9\ **Last updated:** [June 7, 2024, 3:34pm UTC](https://community.freefem.org/t/freefem-petsc-ubuntu/3289 "2024-06-07T15:34:50Z")
Hello everyone, I am a FreeFem++ learner. Recently, I encountered the issue of FreeFem++ code running very slowly on my CPU. Therefore, I wanted to try using PETSc to accelerate it (on a Linux system). I followed the tut… --- ## [Call PETSc matrix operator MatDiagonalSet (…)](https://community.freefem.org/t/call-petsc-matrix-operator-matdiagonalset/1050)
**Author:** [@yongxing](https://community.freefem.org/u/yongxing)\ **Replies:** 38\ **Last updated:** [June 3, 2024, 3:09pm UTC](https://community.freefem.org/t/call-petsc-matrix-operator-matdiagonalset/1050 "2024-06-03T15:09:12Z")
Dear all, I need to set a pressure reference point in my parallel FSI code by modifying the matrix, and I realise the following PETSc function may allow me to do this: MatDiagonalSet (…) Has this been implemented in F… --- ## [Uzawa scheme for stokes bingham flow](https://community.freefem.org/t/uzawa-scheme-for-stokes-bingham-flow/3233)
**Author:** [@Alice](https://community.freefem.org/u/Alice)\ **Replies:** 29\ **Last updated:** [June 3, 2024, 10:13am UTC](https://community.freefem.org/t/uzawa-scheme-for-stokes-bingham-flow/3233 "2024-06-03T10:13:48Z")
Hi all, I have written uzawa scheme for Bingham stokes flow on freefem. It is supposed to change when the bn number changes. However when I compile with different bn numbers it does not change. Could anyone help me? He… --- ## [Non-uniform initial condition for using Labels](https://community.freefem.org/t/non-uniform-initial-condition-for-using-labels/3281)
**Author:** [@airwarriorg91](https://community.freefem.org/u/airwarriorg91)\ **Replies:** 2\ **Last updated:** [June 3, 2024, 4:45am UTC](https://community.freefem.org/t/non-uniform-initial-condition-for-using-labels/3281 "2024-06-03T04:45:16Z")
Hello, I am importing my meshed geometry from GMSH to FreeFEM along with the labels. I want to implement the following I.C. using labels. I tried using implicit function approach but it doesn’t work. U = {1.0 at inlet … --- ## [Reconstruction of the internal problem matrix](https://community.freefem.org/t/reconstruction-of-the-internal-problem-matrix/3270)
**Author:** [@wdachub](https://community.freefem.org/u/wdachub)\ **Replies:** 2\ **Last updated:** [June 1, 2024, 7:08am UTC](https://community.freefem.org/t/reconstruction-of-the-internal-problem-matrix/3270 "2024-06-01T07:08:57Z")
Hello to all of you FreeFem users, Thank you for your help in advance. Acoording to the documentation, in a problem, the keyword init controls the reconstruction of the internal problem matrix. If init is set to false … --- ## [Inquiries about solving the N-S equation, projection algorithm and parallel](https://community.freefem.org/t/inquiries-about-solving-the-n-s-equation-projection-algorithm-and-parallel/3006)
**Author:** [@quentin](https://community.freefem.org/u/quentin)\ **Replies:** 16\ **Last updated:** [May 30, 2024, 11:49am UTC](https://community.freefem.org/t/inquiries-about-solving-the-n-s-equation-projection-algorithm-and-parallel/3006 "2024-05-30T11:49:00Z")
Hello everyone， I am not very familiar with FEM and have limited knowledge about its implementation for the Navier-Stokes equation. Currently, I am trying to understand the principles of FEM and parallel computing, but … --- ## [Smallest positive imaginary eigenvalue](https://community.freefem.org/t/smallest-positive-imaginary-eigenvalue/3276)
**Author:** [@Amitkaush](https://community.freefem.org/u/Amitkaush)\ **Replies:** 6\ **Last updated:** [May 29, 2024, 1:10pm UTC](https://community.freefem.org/t/smallest-positive-imaginary-eigenvalue/3276 "2024-05-29T13:10:52Z")
I am trying to solve an eigenvalue problem and I am concerned with finding the smallest positive imaginary eigenvalue. How to find it using EPSSolve? --- ## [Problem solving using Homogenization method](https://community.freefem.org/t/problem-solving-using-homogenization-method/3278)
**Author:** [@Edi1](https://community.freefem.org/u/Edi1)\ **Replies:** 0\ **Last updated:** [May 28, 2024, 10:45am UTC](https://community.freefem.org/t/problem-solving-using-homogenization-method/3278 "2024-05-28T10:45:30Z")
Hello, the code is always stopping at the prob command and i think the problem comes from the mesh creation of the spheres but still can not detect where. Here is the code i am working on: load “msh3” // provides func… --- ## [Pressure projection methods](https://community.freefem.org/t/pressure-projection-methods/3247)
**Author:** [@LXX](https://community.freefem.org/u/LXX)\ **Replies:** 25\ **Last updated:** [May 28, 2024, 2:17pm UTC](https://community.freefem.org/t/pressure-projection-methods/3247 "2024-05-28T14:17:43Z")
Hello, everyone. I’m a beginner in FreeFEM. Currently, I’m attempting to decouple the velocity field and pressure field of the Navier-Stokes equations using the pressure projection method. In the first step, I aim to ca… --- ## [Find the lagest function value on the boundary](https://community.freefem.org/t/find-the-lagest-function-value-on-the-boundary/3256)
**Author:** [@wdachub](https://community.freefem.org/u/wdachub)\ **Replies:** 5\ **Last updated:** [May 27, 2024, 11:05am UTC](https://community.freefem.org/t/find-the-lagest-function-value-on-the-boundary/3256 "2024-05-27T11:05:12Z")
Hello to all of you FreeFem users, I want to find the largest value of my PDE solution on the boundary of the domain. I know “u.max” gives the largest value of the u on the mesh, but I don’t know how to modify it to get… --- ## [FFDDM transfert scalar field from complex FE space to real one](https://community.freefem.org/t/ffddm-transfert-scalar-field-from-complex-fe-space-to-real-one/2047)
**Author:** [@altar31](https://community.freefem.org/u/altar31)\ **Replies:** 6\ **Last updated:** [October 10, 2022, 4:12pm UTC](https://community.freefem.org/t/ffddm-transfert-scalar-field-from-complex-fe-space-to-real-one/2047 "2022-10-10T16:12:12Z")
Dear FreeFEM community, I’m actually trying to solve a multiphysics problem in parallel using ffddm. I’m struggle to transfer some electromagnetic quantities (modulus) between two distributed finite element space : fro… --- ## [Measure/check element size in a 3D mesh](https://community.freefem.org/t/measure-check-element-size-in-a-3d-mesh/1991)
**Author:** [@yhao](https://community.freefem.org/u/yhao)\ **Replies:** 4\ **Last updated:** [September 7, 2022, 8:50am UTC](https://community.freefem.org/t/measure-check-element-size-in-a-3d-mesh/1991 "2022-09-07T08:50:43Z")
Hi everyone, I am trying to get the maximum, minimum, and average element size in a 3D mesh. I found there is a command hTriangle that can check the mesh size of a 2D mesh. I want to ask if there is any way to get the s… --- ## [Poiseuille profil, Stokes , Uzawa](https://community.freefem.org/t/poiseuille-profil-stokes-uzawa/197)
**Author:** [@TheodoraVa3](https://community.freefem.org/u/TheodoraVa3)\ **Replies:** 4\ **Last updated:** [May 25, 2024, 7:43am UTC](https://community.freefem.org/t/poiseuille-profil-stokes-uzawa/197 "2024-05-25T07:43:41Z")
Hi everyone, I am new to this amazing world of FreeFem users and I am having some issues with my work on a Poiseuille profil for Stokes equations with the Uzawa method. My results are totally wrong but I don’t see what… --- ## [Solve 3D thermoelasticity with PETSc](https://community.freefem.org/t/solve-3d-thermoelasticity-with-petsc/3264)
**Author:** [@Timothee99](https://community.freefem.org/u/Timothee99)\ **Replies:** 6\ **Last updated:** [May 24, 2024, 3:57pm UTC](https://community.freefem.org/t/solve-3d-thermoelasticity-with-petsc/3264 "2024-05-24T15:57:21Z")
Hello there ! I am trying to solve a 3D thermoelastic system on a cylinder but I encounter a few problems with the use of PETSc (and perhaps iovtk). Indeed, I do not obtain the same mechanical results when I use more p… --- ## [Simulation of a beam](https://community.freefem.org/t/simulation-of-a-beam/3261)
**Author:** [@Oramastein1](https://community.freefem.org/u/Oramastein1)\ **Replies:** 3\ **Last updated:** [May 23, 2024, 9:35am UTC](https://community.freefem.org/t/simulation-of-a-beam/3261 "2024-05-23T09:35:31Z")
Hello, good morning everyone, the truth is I’m new to this, I was supported to make a code for the simulation of a beam simply supported with a point load, but to run the code and display it does not contemplate the defo… --- ## [Fluid-Structure Analysis 3d model](https://community.freefem.org/t/fluid-structure-analysis-3d-model/3265)
**Author:** [@zoumpou](https://community.freefem.org/u/zoumpou)\ **Replies:** 0\ **Last updated:** [May 23, 2024, 10:20am UTC](https://community.freefem.org/t/fluid-structure-analysis-3d-model/3265 "2024-05-23T10:20:28Z")
Hello, i have written a code for an FSI analysis for a 3d model an i tried to apply also a wave formula to the fluid in my model. When i run the code i see that i don’t get any errors but i also don’t get all the results… [Previous page](https://community.freefem.org/c/general-discussion/7.md?page=17) [Next page](https://community.freefem.org/c/general-discussion/7.md?page=19)