Questions tagged [mesh]
The mesh tag has no usage guidance.
143
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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....
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62
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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 ...
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70
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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 ...
- 283
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39
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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:
...
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49
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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 ...
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43
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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 ...
- 607
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2
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114
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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 ...
- 263
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65
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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\}...
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77
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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 ...
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1
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256
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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 ...
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351
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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 ...
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88
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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 ...
- 263
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74
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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 ...
- 113
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76
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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 ...
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54
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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 ...
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58
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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/...
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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 ...
- 297
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93
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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 ...
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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 ...
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84
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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 ...
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85
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structured quad mesh with transition zone
I wonder which software can be used to generate the mesh like below. Anybody has an idea?
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270
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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 (...
- 261
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36
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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 ...
- 323
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53
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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 ...
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286
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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
...
- 304
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76
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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 ...
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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 (...
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130
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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 ...
- 261
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233
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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 ...
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268
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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://...
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808
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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 ...
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142
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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 ...
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537
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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 ...
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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 ...
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430
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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 ...
- 304
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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 ...
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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 ...
- 304
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2
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529
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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 ...
- 607
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75
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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 $\Delta f = 4$...
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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) ...
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2
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675
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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 ...
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23
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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?
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132
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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 ...
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100
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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 ...
- 481
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86
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Parallel mesh partitioning
When a mesh partitioning takes place and every process works on a part of the mesh is any way to rename the global numbering of nodes(on each process) into a local numbering?Is there any software that ...
- 481
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197
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Compute mass matrix in vibrations problem by using finite element method
I have to compute the mass matrix of a Hexahedral mesh.
There are 3 methods to compute mass matrix. I'm interested in one method which consists of dividing the mass of the element by the number of ...
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2
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2k
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How to determine the Jacobian Ratio for triangle element?
I am trying to implement an algorithm to find the Jacobian ratio for each triangle in mesh as a part of mesh quality check.
Let's say that I have vertices of the triangle: $P_1(x_1, y_1, z_1)$, $P_2(...
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226
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Effect of mesh size on solution curves for a 1D problem
I'm interested in studying the effect of mesh size on the behavior of the solution curves of 1D convection-diffusion problem.
$$\frac{\partial C}{\partial t} = D\frac{\partial ^2 C}{\partial x^2} - ...
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231
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mesh dependence of numerical adjoint solution
I am solving the steady, two-dimensional adjoint Euler equations, $$A_x^T \partial_x \Psi + A_y^T \partial_y \Psi = 0$$, where $A_x = \partial F_x/\partial U$ and $A_y= \partial F_y/\partial U$ are ...
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Produce vertex displacements from volumetric shrinkage data on unstructured meshes
I was wondering what would be an efficient way to produce compatible displacements for mesh nodes/vertices if the computed data is volume shrinkage of each element/cell in the unstructured mesh?
...
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