# General Discussion **URL:** https://community.freefem.org/c/general-discussion/7.md?page=65 [Latest](https://community.freefem.org/latest.md) · [Categories](https://community.freefem.org/categories.md) **Page:** 66 --- ## [How to apply concentrated load in beam example](https://community.freefem.org/t/how-to-apply-concentrated-load-in-beam-example/173)
**Author:** [@raymonraymon](https://community.freefem.org/u/raymonraymon)\ **Replies:** 2\ **Last updated:** [January 1, 2021, 8:17pm UTC](https://community.freefem.org/t/how-to-apply-concentrated-load-in-beam-example/173 "2021-01-01T20:17:00Z")
I found beam test in the manual， I would like to compare with other commercial software with this example. So I want to know how to apply concentrated load on the beam’s corner. --- ## [Neumann boundary condition on both sides of a boundary](https://community.freefem.org/t/neumann-boundary-condition-on-both-sides-of-a-boundary/709)
**Author:** [@amtravco](https://community.freefem.org/u/amtravco)\ **Replies:** 2\ **Last updated:** [December 31, 2020, 8:31pm UTC](https://community.freefem.org/t/neumann-boundary-condition-on-both-sides-of-a-boundary/709 "2020-12-31T20:31:22Z")
I would like to impose a Neumann (normal derivative specified) boundary condition such that the normal derivative points away from the boundary on one side but into it on the other. Consider a square box with a “boundar… --- ## [Metal Cutting Simulation](https://community.freefem.org/t/metal-cutting-simulation/714)
**Author:** [@vpavitharan](https://community.freefem.org/u/vpavitharan)\ **Replies:** 2\ **Last updated:** [December 30, 2020, 2:30pm UTC](https://community.freefem.org/t/metal-cutting-simulation/714 "2020-12-30T14:30:52Z")
Hello all, So I am a Beginner in FREEFEM and currently I am working on a project which requires the simulation of metal cutting process and results of parameter such as Cutting force ,Temperature distribution are to be… --- ## [Define initial value of an function](https://community.freefem.org/t/define-initial-value-of-an-function/707)
**Author:** [@Aicha](https://community.freefem.org/u/Aicha)\ **Replies:** 1\ **Last updated:** [December 28, 2020, 2:16pm UTC](https://community.freefem.org/t/define-initial-value-of-an-function/707 "2020-12-28T14:16:05Z")
Hi, the initial value of a solution v(x,t) of an equation is defined by: v(x,0)= v\_0 \\times Id\_{\[0,x\_0\]} where Id\_{\[0,x\_0\]} (x) is equal to 1 when x \\in \[0,x\_0\], else it’s equal to 0. My question is: in FreeFem++, how… --- ## [Optimal coefficient in movemesh](https://community.freefem.org/t/optimal-coefficient-in-movemesh/706)
**Author:** [@Sunrise](https://community.freefem.org/u/Sunrise)\ **Replies:** 4\ **Last updated:** [December 27, 2020, 7:42pm UTC](https://community.freefem.org/t/optimal-coefficient-in-movemesh/706 "2020-12-27T19:42:38Z")
Dear all, how to choose the optimal coefficient ‘dt’ when moving a mesh Th = movemesh(Th,\[x+dtvx,y+dtvy\]); Thank you in advance! --- ## [Cumputing the eigenvalues of the 2d wave equation](https://community.freefem.org/t/cumputing-the-eigenvalues-of-the-2d-wave-equation/710)
**Author:** [@mordechaiy](https://community.freefem.org/u/mordechaiy)\ **Replies:** 1\ **Last updated:** [December 27, 2020, 1:24pm UTC](https://community.freefem.org/t/cumputing-the-eigenvalues-of-the-2d-wave-equation/710 "2020-12-27T13:24:43Z")
Dear FF++ user, I would like to ask please, how can I solve the generalized eigen values for computing the eigenvalues of the 2D wave equation in a square, using PETSc and SLEPc? Thanks in advance, Mordechai. --- ## [Problem with three equations](https://community.freefem.org/t/problem-with-three-equations/682)
**Author:** [@Aicha](https://community.freefem.org/u/Aicha)\ **Replies:** 1\ **Last updated:** [December 12, 2020, 11:04am UTC](https://community.freefem.org/t/problem-with-three-equations/682 "2020-12-12T11:04:04Z")
Hi, i have the following problem: three equations with three unknown u,i,v: The data are: L=1, T=1000, k\_2=10, k\_3=1, D=0.001, sigma1=1, sigma2=1, u0=1, i0=0, v0=1, x0=0.3 I try to write the following program , but… --- ## [Error in a program](https://community.freefem.org/t/error-in-a-program/697)
**Author:** [@Aicha](https://community.freefem.org/u/Aicha)\ **Replies:** 1\ **Last updated:** [December 21, 2020, 10:44pm UTC](https://community.freefem.org/t/error-in-a-program/697 "2020-12-21T22:44:05Z")
Hi, i try to program with FF+ the following algo i write the followin code but the problem is that i obtain zeo in each step. Can any one help me to find theproblem in my progam? Please. code.edp (1.4 KB) --- ## [Label of border after using movemesh](https://community.freefem.org/t/label-of-border-after-using-movemesh/705)
**Author:** [@Sunrise](https://community.freefem.org/u/Sunrise)\ **Replies:** 2\ **Last updated:** [December 26, 2020, 6:04pm UTC](https://community.freefem.org/t/label-of-border-after-using-movemesh/705 "2020-12-26T18:04:02Z")
Dear all, does border label still the same after using movemesh? if not, how to extract border from mesh? Thank you in advance! --- ## [Curvature (tangential divergence of normal vector)](https://community.freefem.org/t/curvature-tangential-divergence-of-normal-vector/704)
**Author:** [@Sunrise](https://community.freefem.org/u/Sunrise)\ **Replies:** 3\ **Last updated:** [December 26, 2020, 6:01pm UTC](https://community.freefem.org/t/curvature-tangential-divergence-of-normal-vector/704 "2020-12-26T18:01:54Z")
Dear all, how to define curvature (tangential divergence of normal vector)? Thank you in advance! --- ## [Freefem has stopped](https://community.freefem.org/t/freefem-has-stopped/708)
**Author:** [@zese](https://community.freefem.org/u/zese)\ **Replies:** 0\ **Last updated:** [December 24, 2020, 12:40pm UTC](https://community.freefem.org/t/freefem-has-stopped/708 "2020-12-24T12:40:48Z")
Dear users I have written a code to compute eigenvalue equation. when I run it on my PC it works properly; however, when I run it by another PC after solving eigenvalue it stops working and doesn’t give me any result. m… --- ## [Exchange of estimated temperature between two mesh](https://community.freefem.org/t/exchange-of-estimated-temperature-between-two-mesh/702)
**Author:** [@Mik](https://community.freefem.org/u/Mik)\ **Replies:** 5\ **Last updated:** [December 23, 2020, 10:10am UTC](https://community.freefem.org/t/exchange-of-estimated-temperature-between-two-mesh/702 "2020-12-23T10:10:07Z")
Hello All, My question is regarding the transfer of data from one mesh to another. In my first iteration, I am estimating the temperature in a smaller domain (Domain 1) and then I add a section (Domain 2) to the smalle… --- ## [Intalledges command and reduced order model](https://community.freefem.org/t/intalledges-command-and-reduced-order-model/701)
**Author:** [@mordechaiy](https://community.freefem.org/u/mordechaiy)\ **Replies:** 0\ **Last updated:** [December 22, 2020, 11:52pm UTC](https://community.freefem.org/t/intalledges-command-and-reduced-order-model/701 "2020-12-22T23:52:32Z")
Dear FF++ users, I would to ask please two separately questions , In which case (or cases) should one use the “intalledges” command rather than the “int1d” command? Are there any libraries in FF++ that are dedicat… --- ## [Simulating using sensors](https://community.freefem.org/t/simulating-using-sensors/688)
**Author:** [@mordechaiy](https://community.freefem.org/u/mordechaiy)\ **Replies:** 4\ **Last updated:** [December 22, 2020, 10:39pm UTC](https://community.freefem.org/t/simulating-using-sensors/688 "2020-12-22T22:39:48Z")
Dear FF++ users, I am solving the 2D wave equation on a square, I am interested to save the values of the solution at each time of the simulation but only in few places on the mesh which simulates sensors locations, the… --- ## [Charge calculation using Laplacian](https://community.freefem.org/t/charge-calculation-using-laplacian/698)
**Author:** [@dmm](https://community.freefem.org/u/dmm)\ **Replies:** 0\ **Last updated:** [December 21, 2020, 3:02pm UTC](https://community.freefem.org/t/charge-calculation-using-laplacian/698 "2020-12-21T15:02:29Z")
Hello. I tried to calculate charge using volume integral of Laplacian of potential and got strange results. In order to simplify the task, I used 2d case here (capacitor model). The results are similar to the 3d case. F… --- ## [Coordinates of DOFs](https://community.freefem.org/t/coordinates-of-dofs/696)
**Author:** [@Alex](https://community.freefem.org/u/Alex)\ **Replies:** 2\ **Last updated:** [December 19, 2020, 12:21pm UTC](https://community.freefem.org/t/coordinates-of-dofs/696 "2020-12-19T12:21:18Z")
Hello, I am trying to find the easiest way to get the coordinates of dofs for a piecewise quadratic function u1 over a 3D mesh: mesh3 Th3 = tetg(ThSurf, regionlist=domain); fespace Vh2(Th3,P2, periodic=\[\[XminVal, y, z… --- ## [Explicit and implicit Euler Schems](https://community.freefem.org/t/explicit-and-implicit-euler-schems/695)
**Author:** [@Aicha](https://community.freefem.org/u/Aicha)\ **Replies:** 0\ **Last updated:** [December 18, 2020, 8:18pm UTC](https://community.freefem.org/t/explicit-and-implicit-euler-schems/695 "2020-12-18T20:18:17Z")
Hi, i have the following system: An explicit Euler scheme of the equations (0.1) and (0.2) give: real t=0.0; real dt=0.1; real tau=1; real n= tau/dt; Vh U, I, Udecale, Idecale; (Udecale -U)/dt = -k2UV (Idecal… --- ## [Boundary conditions](https://community.freefem.org/t/boundary-conditions/694)
**Author:** [@Aicha](https://community.freefem.org/u/Aicha)\ **Replies:** 0\ **Last updated:** [December 16, 2020, 3:53pm UTC](https://community.freefem.org/t/boundary-conditions/694 "2020-12-16T15:53:40Z")
Hi, i have the following code and i want to add the boundary condition dV/dx(L,t)=0, dV/dx(0,t)=0 and the initial conditions U(x,0)=1, I(x,0)=0, V(x,0)=1 How we can do this please? I write some examples in FF++, i t… --- ## [Non linear coupled system](https://community.freefem.org/t/non-linear-coupled-system/692)
**Author:** [@Aicha](https://community.freefem.org/u/Aicha)\ **Replies:** 1\ **Last updated:** [December 15, 2020, 8:24pm UTC](https://community.freefem.org/t/non-linear-coupled-system/692 "2020-12-15T20:24:54Z")
Hi, i search an example to resolve a coupled non linear system with FreeFem++. Thank you in advance. --- ## [\[SOLVED\] Savemesh to save mesh under binary format](https://community.freefem.org/t/solved-savemesh-to-save-mesh-under-binary-format/693)
**Author:** [@LucasPa](https://community.freefem.org/u/LucasPa)\ **Replies:** 3\ **Last updated:** [December 16, 2020, 9:00am UTC](https://community.freefem.org/t/solved-savemesh-to-save-mesh-under-binary-format/693 "2020-12-16T09:00:42Z")
Hi, I attended last week the expert tutorial during the FreeFem Days. As far as I understood, Pierre Jolivet explained that mesh can be saved under a binary format if the following line is put in a script: savemesh(Th,… --- ## [Error for parallel simulation](https://community.freefem.org/t/error-for-parallel-simulation/691)
**Author:** [@zese](https://community.freefem.org/u/zese)\ **Replies:** 1\ **Last updated:** [December 15, 2020, 7:52pm UTC](https://community.freefem.org/t/error-for-parallel-simulation/691 "2020-12-15T19:52:38Z")
Dear users I am planning to run my simulation in parallel. it is an optimal control simulation; however, after solving 37 iterations it stops and show some errors as follow. do you know what the problem might be? \*\* Er… --- ## [Multi-object analysis](https://community.freefem.org/t/multi-object-analysis/690)
**Author:** [@ilk](https://community.freefem.org/u/ilk)\ **Replies:** 0\ **Last updated:** [December 14, 2020, 3:49am UTC](https://community.freefem.org/t/multi-object-analysis/690 "2020-12-14T03:49:05Z")
Hi, I’m new to finite element analysis and freefem, now I want to achieve a project about extrusion. I would like to ask please, is there any way to analysis interaction between multiple objects in freefem? Thanks in … --- ## [Moving an object](https://community.freefem.org/t/moving-an-object/689)
**Author:** [@ilk](https://community.freefem.org/u/ilk)\ **Replies:** 0\ **Last updated:** [December 14, 2020, 2:31am UTC](https://community.freefem.org/t/moving-an-object/689 "2020-12-14T02:31:46Z")
Dear FF++ users, I’m solving a 3D elastic problem, and I want to know if it’s possible to move an object. Just like in abaqus, use boundary condition to control an object’s movement in different step. Thanks, Elvin --- ## [Derivative operator](https://community.freefem.org/t/derivative-operator/675)
**Author:** [@mordechaiy](https://community.freefem.org/u/mordechaiy)\ **Replies:** 4\ **Last updated:** [December 14, 2020, 1:24am UTC](https://community.freefem.org/t/derivative-operator/675 "2020-12-14T01:24:47Z")
Dear FreeFem users, I would like to ask please, suppose u is a “fespace” function defined on a two dimensional mesh, how does the operator dx(u) approximate u? Thanks in advance, Mordechai. --- ## [Problem import 3D file .msh](https://community.freefem.org/t/problem-import-3d-file-msh/684)
**Author:** [@chaimaa](https://community.freefem.org/u/chaimaa)\ **Replies:** 9\ **Last updated:** [December 13, 2020, 5:14pm UTC](https://community.freefem.org/t/problem-import-3d-file-msh/684 "2020-12-13T17:14:28Z")
hello, i’m trying to import 3D mesh from gmsh by using: load"gmsh" mesh3 Th=gmshload3(“Part1.msh”); plot(Th,cmm=“Th mesh read from GMSH”,wait=1); savemesh(Th,“Th3.mesh”); but it give me : edges in 3D mesh are not … --- ## [Problem with shell extrusion](https://community.freefem.org/t/problem-with-shell-extrusion/687)
**Author:** [@ilk](https://community.freefem.org/u/ilk)\ **Replies:** 0\ **Last updated:** [December 13, 2020, 4:02pm UTC](https://community.freefem.org/t/problem-with-shell-extrusion/687 "2020-12-13T16:02:39Z")
Hello, I am a newbie on FreeFEM and I want to solve a squeeze problem. The problem is this: Two rigid plates sandwich a curved plate made of elastic material, gradually move one of the rigid plates, and finally flatten… --- ## [Key words: mapu & mapt](https://community.freefem.org/t/key-words-mapu-mapt/683)
**Author:** [@yongxing](https://community.freefem.org/u/yongxing)\ **Replies:** 2\ **Last updated:** [December 12, 2020, 12:26pm UTC](https://community.freefem.org/t/key-words-mapu-mapt/683 "2020-12-12T12:26:22Z")
Dear FreeFEM user, Can someone tell me the meaning of mapu=\[ \] in the following expressoin, unfortunately I cannot find these key words from FreeFEM++ manual. varf ab( \[u,v,p\], \[lamxh,lamyh,Xh,Yh\] ) = int2d(Ths, qft=… --- ## [How we define a mesh in 1 D](https://community.freefem.org/t/how-we-define-a-mesh-in-1-d/680)
**Author:** [@Aicha](https://community.freefem.org/u/Aicha)\ **Replies:** 3\ **Last updated:** [December 10, 2020, 10:20pm UTC](https://community.freefem.org/t/how-we-define-a-mesh-in-1-d/680 "2020-12-10T22:20:07Z")
Hi, how we define mesh of an interval \[a,b\] with FreeFem++? Thank’s in advance --- ## [Acoustics Simulation](https://community.freefem.org/t/acoustics-simulation/315)
**Author:** [@ChrisK](https://community.freefem.org/u/ChrisK)\ **Replies:** 1\ **Last updated:** [December 9, 2020, 4:40pm UTC](https://community.freefem.org/t/acoustics-simulation/315 "2020-12-09T16:40:17Z")
Hello, I am a relatively new user of FreeFEM. I want to simulate acoustics in a room excited by a gearbox. what will be the desired boundary conditions to find pressure field? Any idea which should be the value to im… --- ## [Problem with syntax error in writing problem](https://community.freefem.org/t/problem-with-syntax-error-in-writing-problem/677)
**Author:** [@amtravco](https://community.freefem.org/u/amtravco)\ **Replies:** 2\ **Last updated:** [December 9, 2020, 4:37pm UTC](https://community.freefem.org/t/problem-with-syntax-error-in-writing-problem/677 "2020-12-09T16:37:56Z")
I’m trying to solve a system of differential equations given in Cordier et al., 4702 IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY, VOL. 9, NO. 4, DECEMBER 1999. The equations are quite complicated, so I won’t try to r… [Previous page](https://community.freefem.org/c/general-discussion/7.md?page=64) [Next page](https://community.freefem.org/c/general-discussion/7.md?page=66)