Questions tagged [mesh]
Questions on the use and creation of meshes including the use of MeshRegion, ElementMesh, and TetGenLink.
653
questions
5
votes
2answers
343 views
Problem while exporting PDF vs PNG
I have the following RegionPlot (which code I don't present since it comes from a long expression):
When I right click on it (within the notebook) and try to save ...
3
votes
1answer
170 views
3D FEM Mesh - Accessing values of individual boundary elements
I have 3D mesh and calculate the heat equation using NDSolve. I want to access the temperature values on the individual boundary elements to solve another problem (...
7
votes
1answer
82 views
FEM Mesh - how to get elements belonging to ElementMarker
I want to get a list of all boundary elements belonging to a certain ElementMarker of a boundary mesh.
This code creates a simple mesh and allows to inspect the <...
3
votes
1answer
71 views
FEM Meshrefinement for 1D Interval and Elements of order 2
I would like to create a 1D mesh of the intervall (-pi/2,pi/2) for solving a DE with FEM, with more elements close to +-1 - these elements should be of order 2, since order 1 elements yield too low ...
5
votes
1answer
64 views
3D FEM - How to use element markers for boundary integration
I am having trouble integrating over some curved boundaries and was thinking about using the element markers of the boundary mesh for integration rather than conditionals.
Is it possible to use ...
2
votes
0answers
123 views
NURBS model from a entire mesh
I have a mesh in STL file format and imported it into Mathematica.
data=Import["mesh.stl"];
or
...
1
vote
0answers
44 views
Mesh Control Problem
I am having trouble combining two graphical objects. The problem has to do with controlling mesh lines. The simplest failing example is combining a circle graphics primitive with a RegionPlot. Either ...
3
votes
0answers
68 views
Custom mesh to help with a Fokker Planck eqn (refined rectangular mesh?)
Physicist here, new to SE and fairly new to MMA. I'm looking to solve a Brownian motion problem with inertia (m ≠ 0) and a velocity dependent diffusion coefficient, which in dimensionless units and ...
0
votes
0answers
62 views
Solving differential equation system with FEM when the equations depend on the mesh cell size
I am trying to implement Large eddy simulation with FEM for solving air flow simulation using Smagorinsky sub-grid stress model. In order to implement this there is a parameter (filter size) in the ...
7
votes
3answers
247 views
Smoother boundaries between components of segmented image
I'd like to use boundaries between components of a segmented image to create a mesh for finite elements, as described in Mesh for Images for three materials and meshes with multiple regions from 2D ...
1
vote
1answer
52 views
Two figures in same graph, how to add mesh to figure 1 but not figure 2?
I plot two figures on the same graph. The following code adds mesh to both figures. But how do I add mesh to the first figure only (not to the second figure)?
...
8
votes
4answers
583 views
Mesh from Images for three materials
I want to mesh a figure which contains three different materials (organic-based materials and polymers) using Mathematica.
Namely:
Black color: material A
White color: material B
Grey color: material ...
2
votes
2answers
208 views
How to create a 2D mesh along a specified path?
I am trying to create a mesh along specific lines connecting specific points. Here I used Subdivide to create n steps along the ...
2
votes
2answers
103 views
Parametric Plot: different coordinates for texture and mesh
I try to create a parametric plot which maps from the complex unit circle to a different region in the complex plane. That works fine but I have one problem:
I want to see the images of a mesh with ...
3
votes
1answer
94 views
How to create a 2D mesh and obtain all the coordinates and connectivity
I know this is a really amateur question, but I´m kind of new in here. Though I´ve been trying for the last few days I simply cannot convert a set of points (well actually a region) to a mesh. But ...
6
votes
1answer
127 views
3D FEM Mesh problem - either bad mesh or inaccurate geometry
I am having trouble obtaining a good 3D mesh. I have tried lots of stuff, either resulting in a bad mesh or inaccurate geometry.
My geometry consists of a cuboid with a quarter cylinder cut out on a ...
3
votes
1answer
109 views
Lighting/Mesh problem after GeometricTransform
This is probably a silly question but...
Context
I have gathered from this site Functions to draw sets of concentric 3D rings
as follows:
...
7
votes
1answer
132 views
MeshTools' CylinderMesh fails in MMA version 12.3.1
I cannot run the CylinderMesh function of MeshTools in Mathematica version 12.3.1.
...
3
votes
1answer
104 views
3D meshing of cyllindrical domain into hexahedral elements
I need a solution for generating a hexahedral mesh for a cyllindrical domain in Mathematica/AceFEM. Ideally, it should be close to cyllindrical symmetry not very far from the center. The best option ...
3
votes
1answer
113 views
What does "TetGenTetrahedralize: Tetrahedralize returned an error, 2. mean? Also error number 1,2,3...?
regioncalc5 = ToElementMesh[regioncalc4, MeshRefinementFunction -> ff]
TetGenTetrahedralize: Tetrahedralize returned an error, 2.
3
votes
2answers
76 views
Face vertices of Polyhedron objects are not actually coplanar?
I'm trying to draw "random" polyhedra with exactly $n$ faces. I figured the easiest way to do so was to get an "evenly-spaced" set of $n$ points on the sphere, get their ...
3
votes
1answer
77 views
Shading a surface bound by a curve in 3D
Foundation
Input: unit circle
The exercise deals with transformations of the unit circle, $(\cos \theta, \sin \theta)$. We start with the unit circle with Hue coloring over the angular range of $(-\pi,...
2
votes
0answers
93 views
Create mesh from point cloud
I would like to create a smooth mesh from a point cloud. As an example, let's create a bunch of points from the Hénon-Heiles system
...
0
votes
1answer
41 views
MeshFunctions::invmeshf that resists other solutions
I'm trying to base mesh on the slope of the function. That's why there is a Cross of two partial derivatives.
...
3
votes
1answer
70 views
How can I select both holes to get high density mesh?
I'm new in Mathematica. I'm trying multiple methods to select both holes without success. Any help will be helpful. Thanks.
...
1
vote
1answer
110 views
Running out of RAM because of a loop
I'm working with some Voronoi diagrams, and I want to find the perimeter and area of each polygon in it. I think I accomplish that, but I have a problem with RAM memory management. This is a ...
5
votes
1answer
103 views
Meshing Accuracy in 3d
The Element Mesh Generation tutorial describes how good mesh accuracy is achieved through adjusting boundary nodes so they match the region boundary. This is illustrated with this example:
...
6
votes
1answer
86 views
How to generate an heterogeneous mesh
I'd like to generate a mesh with a big variance in cell size. Something like
I'd prefer not to rely on a vertex model and perhaps use something simpler, like ...
4
votes
1answer
83 views
Mesh refinement along grain boundaries
I have again a mesh related question. I want to do simulations on a microstructure and therefore I have to mesh it. That works fine, but the refinement of the grain boundaries does not work and let &...
6
votes
1answer
129 views
Defining mesh size for NDSolve
I want to see the effect of mesh size on the solution curves while simulating convection-diffusion - point sink via NDSolve FEM.
In the following code (ref also related to this post):
I'd like to know ...
12
votes
4answers
2k views
How can we find the longitude that cuts all the land on Earth in half?
Mathematica has already a specific function, RegionCentroid, that can be utilized to calculate the geographic center of any region. As it has been discussed in here ...
3
votes
1answer
74 views
Does DelaunayMesh use exact computations? What is the treatment of non-generic cases?
Computing Delaunay complexes can be sensitive to numerical instabilities, especially in higher dimensions. I would like to know how much I can rely on Mathematica's answers when using ...
2
votes
2answers
133 views
AceFem Error in SMTShowMesh
I consider for a calculation a sphere embedded within a matrix. To plot the results and especially the behavior around the spherical inclusion I want to "cut" through the matrix. That seems ...
3
votes
1answer
139 views
Create a spherical Hex mesh from given surface points
For my calculations I got two spherical meshes. One is a surface mesh of quadrilateral elements and the other is the corresponding "inner" hex mesh. The problem with the meshes is, that the ...
2
votes
3answers
106 views
How to make a 3D listplot with meshlines going only along one cartesian coordinate?
I have an external python code that computes a bunch of data, which I read into Mathematica as a table, so: Import["Documents\Hubbard\Python\data.dat", "Table"];
These files are ...
0
votes
0answers
43 views
Export 3D Mesh without shading issues
I can export a mesh to a .obj file such as with the following:
...
5
votes
1answer
184 views
FEM: how to redo a composed boundary mesh for better quality?
Suppose you have region with 2 materials: one embedding material (matrix) containing some particles (...
3
votes
1answer
96 views
Export ComplexPlot3D as Mesh with Material
If I generate a complexplot as follows:
a1 = ComplexPlot3D[Log[z], {z, -5 - 5 I, 5 + 5 I}]
I can export it to a 3D mesh (for use in external applications) with:
<...
4
votes
1answer
93 views
3
votes
1answer
79 views
Mesh with Prescribed Vertices
Mathematica has documentation for triangulating regions bounded by curves using e.g. TriangulateMesh. This is very useful for the work that I (aspire to) do drawing pictures of complicated surfaces ...
2
votes
3answers
334 views
5
votes
2answers
132 views
-2
votes
4answers
284 views
Extrude 3D list with thickness n
I have a 3 dimensional list of points which i would like to extrude in z coordinate with thickness n, i.e. z_{i} -> z_{i}+n for all points in z. There is a similar question concerning 2d list where ...
2
votes
1answer
56 views
Plotting fundamental domains of $\mathbb{Z}^{2}$ with additional features [closed]
I'm trying to figure out how to plot a region that looks like this:
The squares don't have to be painted like that, if I could have just light green, gray, light blue and light red it would be great. ...
2
votes
1answer
85 views
Solving PDE with prescribed rectangular mesh
Question: I want to solve a PDE using NDEigensystem. The region is a rectangle Rectangle[{0,-70}, {20, 70}]. How can I make a ...
3
votes
1answer
85 views
0
votes
0answers
32 views
Finding points of intersections between contours and mesh functions in ContourPlot3D
I have this code example that finds plane of zero first derivatives - the intersections of these planes will give the locations of the local extrema. Or at least a good starting point to finding them.
...
1
vote
1answer
84 views
ContourPlot and MeshFunctions issue between versions 11.3 and 12.0
On Mathematica 11.3
This code produces the image below (a set of points that I am then using as a pattern for FindRoot):
...
3
votes
2answers
177 views
How to find the MeshConnectivityGraph[] from a list of independent cell mesh regions?
I'm generating a bunch of points inside a BoundaryMeshRegion. Then I generate the Voronoi mesh of the points, and take the intersection of the Voronoi cells into ...
1
vote
2answers
77 views
How do I discretize Line objects
I have a polygon object that I wish to discretize.
e.g.
points0 = {{0, 0}, {1, 2}, {1, 0}, {0, 0}}
DiscretizeRegion[Line[points0]]
My goal is to increase the ...
