Questions tagged [mesh-generation]
The generation of a set of interconnected geometric objects that approximate a desired domain or region in euclidean space.
3
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0answers
51 views
Gmsh for 3D volume with inclusions
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
90 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 ...
-1
votes
1answer
71 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?
0
votes
0answers
103 views
Using gmsh python api for meshing a model with grouping elements by their volumes and surfaces
I am trying to use GMSH python api for creating 2d meshes of cad formats. I managed to write a script that can generate mesh successfully. However I need to know how elements are separated across ...
4
votes
2answers
460 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
vote
0answers
44 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
votes
2answers
206 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 ...
1
vote
1answer
325 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. ...
0
votes
1answer
130 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
73 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
votes
1answer
54 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
107 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
91 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
vote
0answers
50 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 ...
9
votes
1answer
205 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/...
1
vote
1answer
781 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
1answer
162 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
510 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
933 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
51 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
185 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
91 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
86 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
104 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
votes
1answer
259 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
378 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
77 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
501 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
231 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
123 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
vote
1answer
277 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
63 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
458 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 ...
3
votes
1answer
376 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 ...
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vote
0answers
27 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\\...
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vote
0answers
97 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 ...
6
votes
1answer
242 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 ...
8
votes
1answer
222 views
Does some form of documentation of GMSH exist?
I am looking to implement GMSh into a simualtor that I am going to create. I am looking to integrate the geo, mesh, and post processor modules.
However, looking online, it appears the documentation ...
4
votes
0answers
523 views
Meshing two parts together [closed]
I have two parts, which need to be meshed. One part is located inside another. To simplify the problem, imagine two cubes: one inside another.
Geometries are stored in STL files. From CAD point of ...
11
votes
1answer
3k views
What is a “hanging node” in the finite element meshing?
When reading literatures about finite element method, the term "hanging nodes" can often be encountered. Could anyone tell me what indeed is a hanging node?
0
votes
1answer
655 views
Quadtree type Grid
I would like to code for a quadtree type meshing but don't know how to do. If anyone can help or can share any starting code?
5
votes
1answer
679 views
Meshing options to generate number of the sides of and element (tetgen-triangle)
I wrote a finite element code in fortran 90.
This code is really fast, except the meshing process.
I used triangle and tetgen for meshing in 2D and 3D, respectively, so this process is fast, of ...
4
votes
1answer
997 views
Using Gmsh to create a mesh with zero thickness (quad) interface elements
I acknowledge the following post where a similar question is posed and a very nice answer has been provided:
Is there a mesh generator that will generate zero thickness elements for interfaces?
...
2
votes
0answers
280 views
Adaptive Finite Element Method - Laplace
I'm currently attempting to turn my code for solving the laplace equation using finite element approximations into an adaptive one using the dual weighted residual as my error estimator: i.e. my ...
1
vote
2answers
419 views
structured to unstructured grid - calculating volume of cell
I have a 3-D structured grid that I am trying to convert over to an unstructured grid.
Here is a picture of the 2-D structured grid with the nodes shown. It is axisymmetric about the x axis (y = 0). ...
3
votes
0answers
143 views
matplotlib contourplot for $\log z$ in the Complex Plane $\mathbb{C}$
I tried using Python's matplotlib on the logarithm and here is what I got, a kind of starburst pattern. Since the angle jumps between $\theta = 0$ and $\theta = 2\pi$, contour assumes there is a ...
3
votes
2answers
522 views
How to calculate efficiently mesh edges midpoints?
I have a 2D mesh of triangles used in Finite Element method to discretize the domain. I want to calculate the midpoints of all the edges because I want to use $\mathbb{P}^2$ elements. I am using ...
4
votes
0answers
388 views
Large meshing with tetgen
So I have a point cloud that I am creating a 3D flat rectangular surface from. I'm then turning it into a hollow box and connecting the corners by just dropping this surface mesh down. I need it to ...
1
vote
1answer
2k views
Triangular mesh of a 3D surface
I have an irregular grid of points describing this surface (a large subduction fault in South America). The color is depth. Anyway I have 3D coordinates (lon,lat,depth) at irregular intervals. I'm ...
1
vote
1answer
765 views
Tetrahedral Mesh file format in TETGEN
Ply file formats is used to represent mesh structures in the TETGEN freeware package. All the examples I've seen of 'ply' meshes were used for triangular meshes.
...
