Questions tagged [mesh]

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Mesh movement method causing force oscillations in benchmark 2D FSI problems

I'm relatively new to the FSI world, and I'm dealing with some benchmark FSI problems at first; such as the example of a flap in a channel. (googling fsi benchmark flap 2D leads me to the example ...
Collapse's user avatar
  • 101
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1 answer
66 views

mesh size restriction of spatial discretization in FEMs and FDMs

Is there any mesh size restriction of spatial discretization in FEMs and FDMs (finite difference)? If a mesh is very coarse there is still perhaps nothing to stop the program from running and cause ...
feynman's user avatar
  • 269
-1 votes
1 answer
103 views

What is the name of the theory that combines 3d discretized surfaces and distributed numerical algebra

I've looked into distributed numerical computation work before, but I've realized that 3D applications are all about 3d surfaces and meshes.So I'd like to look into related work on mesh and parallel ...
Haitao Xiao's user avatar
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17 views

uniform refinement is not working in gmsh

I get 0 node and elements when I use -refine command line flag in gmsh. Explicitly writing RefineMesh; in the script produces the original mesh and not a refined one. Am I missing something while ...
Ashb's user avatar
  • 11
3 votes
0 answers
132 views

Fast Fourier Transform on Meshes

I have a (closed, manifold, oriented) triangular mesh for which I build a matrix $L\in\mathbb{R}^{n\times n}$ discretising the negated Laplace-Beltrami operator. The matrix $L$ is symmetric positive ...
lightxbulb's user avatar
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45 views

Meshing inconsistency

New to Gmsh. I am trying to create a very simple mesh that is essentially two cylinders merging into one. So I added two parallel cylinders first (a bit farther from each other). Then I extruded (...
Bernhard Listing's user avatar
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1 answer
131 views

AMR-Capable meshing software that is not based on quad/octrees

I am looking for AMR/re-meshing software (structured grids would suffice) that is NOT based on quad-octrees, i.e., a fixed refinement rate of 2 but (ideally) something user defined, i.e., ratios of 1....
Dan Doe's user avatar
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2 answers
85 views

How to remove triangles in a hollow hemisphere shape?

So I have this code where I am designing a hollow hemispherical shape and I want to create a 3D volume to input it into FEBio software. I am using delaunay triangulation for meshing. But the problem ...
dazemood's user avatar
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93 views

How to use a surface mesh parameterization?

I'm currently playing with the surface mesh parameterizations of the C++ library CGAL. For a mesh with a boundary, the computed uv-space (parameterization domain) is either a disk or a square, and so ...
Stéphane Laurent's user avatar
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0 answers
67 views

Create structured alternate volume mesh in gmsh

I've been trying to create a box mesh in gmsh with a structured and refined layer in the middle, here is the .geo code for it: ...
Gabriel Dante's user avatar
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0 answers
58 views

How best to iterate over three dimensional grid?

My problem is to iterate through $[0.95,1] \times [0.95,1] \times[0.95,1] \in \mathbb{R}^{3}$. Is there a generic way to do this? I was considering rolling it all out and effectively vectorising the ...
KeynesCoeFen's user avatar
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48 views

Efficient cutting of mesh edges

I am looking for efficient algorithms to cut a mesh along edges. I have a (half-edge) mesh and a list of inner edges that I want to cut, such that both are new boundary edges. At each vertex there can ...
allo's user avatar
  • 607
1 vote
2 answers
117 views

Elements on a triangle (FEM)

I am trying to learn about 2D FEM methods. I am trying to understand the generalization of Lagrange polynomial basis from 1D into 2 variable polynomials over triangle domains. The most basic element ...
Makogan's user avatar
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1 vote
0 answers
69 views

Maximal "Convex Augmentation" of a Triangle in 2D Mesh

Consider a convex polygon in $\mathbb{R}^2$ with multiple convex holes in it and suppose that, for now, we have a 2D triangular mesh of the polygon, which is represented by $\mathcal{T} \equiv\{T_i\}...
ArGenya's user avatar
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1 vote
1 answer
78 views

Geometrically nonlinear finite element problem and mesh distortion

In my research on topology optimization of fluid-structure interaction problems (2D), I am using a geometrically nonlinear model to represent the structure. Body/surface forces are extracted from the ...
Mohamed Abdelhamid's user avatar
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1 answer
406 views

GMSH: How can I extrude a surface in a non-linear way?

I am developing a model to represent a dam, shown in the picture below. The geometry in the white circle is the curtain, which is required to be curved. I extruded this 2D face (including the ...
Julio's user avatar
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1 vote
1 answer
618 views

Gmsh: what is the right syntax to iterate over a list of numbers with a For loop on the native language?

I'm new to Gmsh and after browsing many sites I haven't found the answer for this silly error. Using the native language of the software, I'm assigning a value to the Transfinite property of a bunch ...
Julio's user avatar
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2 votes
1 answer
96 views

Min supporting line of a set of points

I am following along Rourke's book and I am trying to do the excercies mentioned in this SO post: Min supporting line for a set of points Design an algorithm to find a line 𝐿 that: has all the ...
Makogan's user avatar
  • 263
1 vote
1 answer
91 views

Unreasonably large deviation in calculations of mean curvature in different algorithms

for my work I am currently trying compare the mean curvature of different meshes. I have the following scheme. I have a ground truth mesh and a comparison mesh, which I want to compare it too. I am ...
jabru's user avatar
  • 113
1 vote
1 answer
83 views

Mesh decomposition using coordinate bisection

I am currently trying to understand the mesh partitioning using coordinate bisection method. The general idea is clear: Looking at the coordinates (either X or Y or Z direction) and splitting the ...
vydesaster's user avatar
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1 answer
59 views

Node connectivity for regular structured meshes

Consider a regular rectangular 2D $r$-$z$ mesh with constant spacing $\Delta r$ along the $r$-axis with $n$ points and spacing $\Delta z$ along the $z$-axis with $m$ points. I thought it would be a ...
wander95's user avatar
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0 answers
65 views

deal.II and curved faces: how can I get the curved description

I'm not a deal.II expert, and while studying step-6 I was reading the documentation of the MappingQ1 class in the deal.II documentation. At some point in the description (https://www.dealii.org/...
FEGirl's user avatar
  • 281
2 votes
0 answers
62 views

Centered finite volume scheme for an advective term on an unstructured/irregular/non-uniform grid

Consider the continuity equation $$\frac{\partial u}{\partial t} + \frac{\partial \Phi}{\partial x} = 0$$ $$\Phi = au + b\frac{\partial u}{\partial x}$$ Suppose I want to solve the above using ...
nicholaswogan's user avatar
1 vote
0 answers
122 views

From 3D to 2D with a STL file

I would like to do a 2D projection from a 3D geometry saved in a stl file and know the distance between the two projected planes. In order to explain better the concept I will start with an almost ...
Daniel's user avatar
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0 answers
68 views

Getting gradient from voxel, is it possible and how?

The R package rmarchingcubes implements a marching cubes algorithm. Given a voxel contructed from a function defining an isosurface, it returns a 3d mesh with some vertex normals. When I plot this ...
Stéphane Laurent's user avatar
-1 votes
1 answer
84 views

Billiard reflection inside a triangular mesh

I am currently interested in billiards and their trajectories. I would like to simulate a billiard inside a water-tight mesh. A mesh basically consists of a list of points in 3D space (vectors with 3 ...
jabru's user avatar
  • 113
2 votes
0 answers
88 views

structured quad mesh with transition zone

I wonder which software can be used to generate the mesh like below. Anybody has an idea?
kstn's user avatar
  • 231
1 vote
2 answers
292 views

Find intersections between mesh and curve inside it

I have a simple square mesh, and a curve (discretised by another mesh) inside it. Here a picture worths thousand words. What I want to achieve is to find, for every cell $K$ of the circular (...
FEGirl's user avatar
  • 281
0 votes
1 answer
39 views

Packages can help to refine parallel mesh and optimize parallel mesh

I have a parallel code. The code is implemented using MPI. I want to find a package that can help to implement global mesh refine and optimize meshes (avoid very thin element). The mesh in my work is ...
Xu Hui's user avatar
  • 323
2 votes
2 answers
55 views

How does RFEM give non-linear results with a two-node mesh?

I did this simple analysis on RFEM, of a rigid-supported beam loaded with a point moment. Before analysis, I didn't assign any kind of mesh manually. When I turn on the FE Mesh visible on Project ...
S. Rotos's user avatar
  • 133
2 votes
3 answers
321 views

How to efficiently get mesh cell/face connectivity?

If I have 3 lists: points, faces and cells that represents a mesh, where: points is a list of x,y,z coordinates, for example ...
Algo's user avatar
  • 304
1 vote
0 answers
77 views

How to determine the orientation of convex/concave hexahedra?

I am writing a code that checks the orientation of a list of vertices (along with face connectivity) describing both convex and concave hexahedra. The face connectivity table stores the list of vertex ...
niran90's user avatar
  • 233
3 votes
2 answers
696 views

Is mesh orthogonality important for FEM?

While studying mesh quality metrics in literature and software documentation, I've seen discussions about mesh orthogonality in Finite Volume Method (FVM) contexts, but not for Finite Element Method (...
Eduardo's user avatar
  • 141
1 vote
1 answer
144 views

Renumbering the nodes for quadratic basis functions for a 2D domain

I have a simple triangulation for a 2D domain, described by the connectivity matrix $T$ and by the point matrix $P$. For didactic purposes, I assembled the stiffness matrix for $-\Delta u = f$ by ...
FEGirl's user avatar
  • 281
0 votes
1 answer
246 views

Visualize a mesh from list of 3D point and faces

I have a list of vertices and faces. Now, I want to create a mesh using the given points and faces list and visualize it. Also, I want to play with the mesh by adding an extra point on the faces. Can ...
nKandel's user avatar
  • 111
5 votes
1 answer
285 views

Solving PDEs in parallel

I have read different approaches on how to solve pdes in parallel which are discretized using finite element method. For example: Non-overlapping domain decomposition approach as mentioned in https://...
spyros's user avatar
  • 481
1 vote
0 answers
987 views

Open-source Hexahedral meshing tools

I'm looking for an open-source automatic meshing tool or library able to generate full or dominant hexahedral mesh starting from a provided arbitrary model i.e. a surface triangular mesh stored in STL ...
Ricla's user avatar
  • 11
2 votes
2 answers
143 views

Software to build a mesh of a surface from points on the surface

I have a set of points $(x_i,y_i,u(x_i,y_i))\in\mathbb{R}^3$, $i=1,\dots N$, over a surface $S$ (from experimental data). I need to calculate the integral of a function $F$ over that surface. If the ...
yemino's user avatar
  • 515
4 votes
2 answers
593 views

Meshing surface of a sphere with a subdomain

I am trying to build a triangle mesh of the surface of a sphere which also includes a subdomain defined by a 'polygon'. Here is a successful example (subdomain defined by the red dots): Note that the ...
Fab von Bellingshausen's user avatar
2 votes
2 answers
84 views

How to refine the tetrahedron if exist two longest length edge?

In some algorithms to refine tetrahedron, we need to calculate the longest edge. background If exist a tetrahedron with node ABCD, it has edges ...
Xu Hui's user avatar
  • 323
1 vote
2 answers
487 views

How to compute gradient of a cell having a boundary face?

In many situations in unstructured mesh solvers, one needs to compute gradient of arbitrary variable $\phi$ such as temperature or velocity at face centers (one of such situations is correction for ...
Algo's user avatar
  • 304
2 votes
1 answer
319 views

Going From Blender Structure defined by triangles to full 3D mesh (Using GMSH?)

I currently have created a model airplane in Blender by drawing a closed volume with triangular planes. I want to do a FEM calculation on this object, meaning I need a fine 3D tetrahedral mesh of this ...
Aleksander Bach Lorentzen's user avatar
2 votes
1 answer
2k views

How to calculate skewness for a mesh?

I am writing a code to calculate mesh quality stats such as: cell volume, face areas and non-orthogonality between faces (basically something like OpenFOAM's ...
Algo's user avatar
  • 304
2 votes
2 answers
665 views

What are the best ways to interpolate a vector field inside (convex) polygons?

I want to interpolate a vector field inside convex polygons in a polygonal mesh. For triangular meshes the scheme uses a piecewise constant interpolation in the triangle, discretized at the center of ...
allo's user avatar
  • 607
0 votes
0 answers
76 views

FEM Meshing artifact at nodes with fewer neighbors

I wrote a 2D-FEM solver to solve some diffusion process and wanted to verify my code with a test problem. The input was $f(x,y) = x^2+y^2$ and I applied the stiffness matrix on it to get $\Delta f = 4$...
murcielagos's user avatar
3 votes
1 answer
174 views

FEM with elastic inhomogeneous properties leads to mesh-induced anisotropy

I'm solving an elastic homogenization problem and I'm having problems with mesh artifacts. I would like to first give a brief summary of what I do: I have a system with inhomogeneous (but isotropic) ...
rasmodius's user avatar
  • 131
2 votes
2 answers
754 views

Visualization of Quad/Octree data Structures

I have a simple C++ quadtree implementation. The implementation subdivides node into four children as if there is more than one point in that particular node. At the moment I want to visualize how ...
Aravindh SK's user avatar
0 votes
0 answers
25 views

Volumetric Mesh Cutting Algorithms For Simulating Sculpture

I am interested in whether there an available algorithms to give me insights on how to cut a volumetric mesh?
Monika's user avatar
  • 109
1 vote
0 answers
153 views

Finding isocontour lines, populating points on said lines (in MATLAB)

I'm trying to extract data from a potential field. I have an example code of a potential field, using meshgrid in MATLAB. I've pasted the code below. What I'd like to do next is 'convert' this field ...
Jon Charron's user avatar
2 votes
1 answer
104 views

Mesh partition quality

I am working on static FE mesh partitioning and in order to achieve a good quality partitioning I want to know how to drecrease interprocessor communication by increasing the connectivity of elements ...
spyros's user avatar
  • 481