Questions tagged [mesh-generation]
The generation of a set of interconnected geometric objects that approximate a desired domain or region in euclidean space.
102
questions
1
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1answer
39 views
Filling a volume with generalised polyhedra
Given a volume (say, some polyhedron), I need to fill it with smaller polyhedra, such that the space is filled as much as possible. The constraints and relaxations are:
(0) For a computation ...
1
vote
1answer
40 views
stretch elliptic mesh to fit a circle
I've generated a 2D O-mesh around an airfoil. Unfortunately, the mesh O shape is not a perfect circle as you can see in the figure below (in the figure I plotted only the mesh nodes in blue). The red ...
2
votes
1answer
58 views
Gmsh meshes flat faces incorrectly for cylindrical faces
I have some C++ code that generates meshes from step files and then analyses these meshes for visibility of the faces from different viewing directions. I currently use CGAL but I would like to switch ...
3
votes
1answer
173 views
Is it possible to remesh with gmsh?
I am currently working on remeshers for my simulations (academic purpose) and I try to find a method to remesh previous meshes using Gmsh.
The first mesh (normalMesh.msh) was created using a .geo file ...
2
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0answers
38 views
Isosurface extraction when you know the derivatives
I have a complicated equation that defines a shape in 3D, and I would like to generate a surface mesh. The shape is defined by an isosurface, i.e. the function is positive inside the shape and ...
1
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0answers
48 views
Duplicate Surface Meshes in different Gmsh files
My objective is to get a conformal surface mesh between two geometries meshed independently in different files.
By example, I can start with a simple cube in one .geo file and mesh this geometry.
...
1
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1answer
106 views
Is there any fundamental difference between meshing for FEM, FVM and FDM?
I am a novice to the field of computational science and have just started studying the FDM and FEM (haven't started on FVM yet). While trying the understand the subject I got this question and trying ...
1
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0answers
49 views
Metis: how to use and tutorial recommendation
I am new to METIS and trying to use it in my fortran code. I read the manual online. But still, I am not sure about how to implement it my code. I tried the test cases in the graphs directory. For ...
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2answers
911 views
Creating 3D Mesh from stl files with gmsh
After long hours of searching for an answer I thought it might be better to ask the community.
The problem I have is that I need to convert STL files to mesh files. I know that I therefore need to ...
4
votes
1answer
51 views
Definition of Lagrange nodes in Gmsh
When gmsh uses higher-order tetrahedral elements, there is an underlying Lagrange basis used to specify the map from reference space to the element. I'm trying to load a gmsh mesh of 3rd degree ...
1
vote
1answer
589 views
How can I coarsen a mesh in Gmsh when 'Mesh options' include 'Refine by splitting' but nothing about coarsening?
I am new to Gmsh and I am having trouble creating a circle with a coarse mesh. I use
Geometry->Elementary entities->Add->Circle
to create the geometry ...
0
votes
1answer
130 views
Load the mesh file with boundary marks
I'm want to load a mesh from a file, generated by triangle, and I want to use the boundary marks of its nodes (boundary marks of the file). It is possible?
Also, I can change the mesh generator (or ...
1
vote
1answer
123 views
How to generate a face list from vertices?
I have a little background in writing toy finite volume CFD codes. In 2D Cartesian scenarios, I typically take $x_{\min}$, $x_{\max}$, $y_{\min}$, $y_{\max}$, and the number of points in $x$ and $y$ ...
3
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0answers
293 views
Gmsh for 3D volume with inclusions [closed]
In an attempt to create three-dimensional volumes with inclusions in Gmsh I stumble upon a problem which was non-existent in the two-dimensional case.
I'm using the OpenCASCADE geometry kernel ...
3
votes
1answer
194 views
Is there any open-source code for a hybrid 2D mesh (triangles and quadrilaterals)?
The question is pretty much the title. Note that I have lots of experience using open-source meshing tool, e.g. Gmsh and OpenFoam blockMesh & snappyHexMesh. Nevertheless, I have no idea on how to ...
0
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1answer
314 views
Connectivity matrix in Finite Element Method in Triangular elements
Imagine a simple triangular base mesh in finite element method with an unknown number of elements (varying by the user). How can connectivity matrix be coded to be generated automatically?
4
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2answers
516 views
3D contour mesh computation
I have the value of a function in three dimensions, $f(x, y, z)$, which varies smoothly.
I would like to compute a 3D mesh where $f(x, y, z)$ has a particular value.
Are there algorithms to do this? ...
1
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0answers
56 views
Efficient initial identification of solid or liquid domains for a block structured Cartesian grid generation system
INTRO
Within the last 5 days I was able to generate a block structured Cartesian grid
generation system with a combination of Fortran,C++ and Python.
I am running intersection tests of the ...
5
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2answers
414 views
Unstructured mesh vs hybrid structured/unstructured for numerical simulations
While answering one of the questions on meshing process, I encountered a lack of understanding on my end for the comparison of the mesh quality.
First, consider an unstructured mesh created in GMSH ...
2
votes
1answer
2k views
Creating a proper quad-mesh in GMSH for an “I”-shaped geometry
I'm trying to make a 2-D quad-only mesh of an "I"-shaped cross-section, with elements of size 5. So far I've managed to make it quad only, but some elements are very distorted when they shouldn't be. ...
1
vote
1answer
543 views
A difference running Gmsh in command line and in GUI for 3-D mesh generation [closed]
In Gmsh, I have a test.geo file. The question is:
if I run gmsh -3 test.geo in the command line, I get the below error.
...
0
votes
1answer
77 views
Structural mechanics simulation using FLUENT compared to analytical solution
This is a continuation of my previous post, 1D analytical solution vs FEM solution for a bar under compression. For some reason, I cannot comment in it.
The analytical solution to the 1-D static ...
0
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1answer
80 views
Gmsh exporting wrong mesh DATA [closed]
so hopefully I'll be using gmsh to make meshes out of 2-D cross sections with o thickness. I tried to make a structured mesh with quad elements of a rectangular ...
5
votes
2answers
112 views
Numerically solving a PDE on an unit tangent bundle
Let $M$ be a manifold and $UT(M)$ its unit tangent bundle. I have a PDE which looks something like
$$
\frac{\partial f}{\partial t}(x,v) = (v\cdot \nabla_x) f(x,v) + \Delta f(x,v)
$$
where $x\in M$, $...
3
votes
1answer
206 views
Compute mesh of the projection of a 3D surface triangulation
Given a triangulated surface in $\Bbb{R}^3$ we can simply project it on a plane. This will result in a family of triangles which do not form a mesh of the projection for the following reasons:
each ...
1
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0answers
61 views
surface triangulation to boundary representation
Are there any open source tools available which can take a surface triangulation of mesh volumes and convert them to a boundary representation?
I am interested in refining multiple region tetrahedral ...
8
votes
1answer
244 views
Resources on mesh generation for finite element methods
I know that this is not really apart of the rules as this is a recommendation question and these don't really have an answer per say. But, like this forum posting: https://stackoverflow.com/questions/...
2
votes
1answer
2k views
Custom Mesh Sizes in GMSH [closed]
I have a simple question today. I am new to GMSH and I am currently learning how to use the software program. I am using GMSH 3.0.4.
What I am looking to do is to set a different mesh size for ...
1
vote
3answers
576 views
Create mesh for complicated 3D object for finite element analysis
I see images of steel connections, concrete dams, and other complicated 3D objects in papers which finite element analysis has been performed on them. My questions are:
How these objects are created ...
1
vote
1answer
791 views
Algorithm to find boundary faces of mesh
I am given the data about nodes and elements of a tetrahedral mesh. What algorithm do I use to find the boundary faces of the mesh?
1
vote
1answer
2k views
Determinant of jacobian matrix
I am using an FEM code written in Fortran which I did not design. For a particular problem, the program complains that the determinant of the Jacobian matrix is inferior to zero.
I vaguely ...
1
vote
0answers
55 views
adaptive / smart grid choice for dynamic programming
I've a read a paper about investing where they used a dynamic programming approach to solve a finite horizon problem, i.e.
$$\max_{x_t} E[u(W_T)] $$
where $u$ is a utility function and $W_T$ ...
9
votes
2answers
241 views
Commonly-used metrics to quantify the irregularity of a triangular mesh
Say you have a triangular mesh on a flat plane.
This has been drawn to eventually solve some problem in mechanics, for example.
A mesh of equilateral triangles is the best inasmuch as the distances ...
1
vote
0answers
149 views
How to generate a tet10 mesh from a tet4 mesh
I am writing a FEN solver on tet10 elements. I right now have a CFD grid gen tool (Pointwise) which generates tet4 meshes. From this I have the element connectivity list and the node list. How do I go ...
2
votes
0answers
114 views
scalable parallel mesh/amr on unstructured grid
I am trying to code a scalable parallel AMR for unstructured grid. There seems to be three approaches for this
a) Store some global grid info on each processor and partition with parmetis (The ...
0
votes
1answer
124 views
From edge-vertex connectivty to face-vertex connectivity?
I am working on mesh generation and optimization and encountered this problem. For example, in the figure below, we have the edge-vertex connectivity:
0-1
1-4
4-5
2-5
3-2
0-3
1-2
1-6
7-6
4-7
...
0
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1answer
366 views
Global numbering of the vertices in a triangulation consisting of quadratic Lagrange elements
I've asked this question on Computational Science SE too.
Consider the following triangulation of a rectangle $(0,a)\times(0,b)$:
We have two types of triangles:
I enumerate the rectangles(...
2
votes
2answers
540 views
Combined translational and rotational meshing in gmsh
For a flow simulation I am trying to reproduce a specific screw element design for an intermeshing co-rotating twin-screw extruder. I am using gmsh (v2.16) where the element is made from a 2D surface ...
1
vote
0answers
95 views
Generate discrete set of points in a feasible region
I have two vectors which specify the bounds $x_{min}$ and $x_{max}$ of the sample space. Also, it has to satisfy the linear constraint $Ax \leq b$.
How to generate an evenly spaced set of points, ...
0
votes
2answers
820 views
2D mesh generator with geometric primitives
The question is exactly as the title:
Which 2D (triangular) mesh generator software can be used which has a set of geometric primitives, controlled mesh size and standard output (.vtk or something ...
4
votes
1answer
360 views
Relationship between number of nodes, elements and sides in a triangular 2D mesh
Say that N is the number of nodes, E the number of elements and S the number of sides in a triangular 2D mesh. Is there a relationship that links these quantities, possibly taking into account that ...
0
votes
1answer
148 views
Meshing software: connectivity between elements and boundary
I am implementing an algorithm which produces a 4d mesh for a cylinder with a given 3d base. This means, I have a 3d mesh and I want to generate a 4d mesh for the corresponding space-time cylinder.
...
1
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1answer
328 views
Library for generating Discontinuous Galerkin FEM mesh
There are a number of packages available for generating Continuous Galerkin (CG) FEM meshes (gmsh, tetgen, netgen, etc.), but I have been unable to find one that generates Discontinuous Galerkin (DG) ...
1
vote
0answers
77 views
Mesh partitioner with user-defined overlap
I am looking for a mesh partitioner, where I can specify overlap, for example h = 3.
I have looked into metis, but I wasn't able to find such a functionality.
Is there any other package which ...
3
votes
1answer
577 views
Library for polygon processing in 3D
I need to process some polygons in 3D. They are typically loaded from an OFF or STL file. Then I need to do some transformations (rotation, move, resize), I'd like to check whether points are inside ...
2
votes
1answer
491 views
Two-dimensional mesh in fem: generating P1, P2, P3,… mesh from a P1 mesh
I have a two-dimensional mesh generated by triangle (the mesh generator software is not relevant). This software generates a perfect mesh for approximate the solution by piecewice linear functions (P1 ...
1
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0answers
30 views
Size of the support
I am working on moving least square approximation. To well-define of this method, the following matrix of size $n \times m$ must be of rank $m$.
For $m=3$
$${\bf A }=\begin{pmatrix}
1&x_1&y_1\\...
1
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0answers
118 views
Finding boundary intersection points with Cartesian grid?
I would like to find the intersection points e.g. $M_x$ and $M_y$ as in the attached figure. The boundary (solid line) is defined by the Lagrangian points.
I am working in C++ (basic - medium ...
1
vote
1answer
361 views
Can TETGEN generate triangulation of a 2D point set?
I would like to link my Fortran 90 application to a library which would give me Delaunay triangulation (for a 2D set of points) and tetrahedralization (for a 3D set of points). As suggested in Fastest ...
5
votes
1answer
248 views
Mesh Generation in 1-D
I am using the method by Brandt in the FAS Multigrid algorithm to estimate the truncation error in a 1-D flow problem and then use that as the basis for generating a mesh(r-adaptation) in 1-D.
The ...
