# Questions tagged [mesh]

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### What is a common file/data format for a mesh (for FEM)?

I'm developing an FEM simulation. For early testing, I will use simple self-written mesher and visualisation of the mesh graph. But I want to prepare my program to use data generated by an existing ...
1k views

### Best Methodologies for Managing a Mesh in Parallel Finite Element Computation?

I am currently developing a domain decomposition method for the solution of the scattering problem. Basically I am solving a system of Helmholtz BVPs iteratively. I discretize the equations using ...
233 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 ...
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### Mesh Independence Study: Is the Independent Mesh Really the Best One?

I am running a mesh independence study. I start with Mesh 1 and proceed up to Mesh 4, each time doubling the number cells in the mesh. In parallel, I am comparing my computational results to ...
3k views

### Shrink wrapping algorithms to make a mesh watertight for 3d printing

I'm investigating algorithms to make a mesh watertight for 3d printing. I'd be very excited to implement such algorithms. The initial input is a mesh which is not watertight and I want to understand ...
478 views

### Mesh ordering algorithms used by COMSOL Multiphysics

Ordering of elements in an unstructured mesh is undoubtedly very important for the performance of computations. For example, it determines the structure of sparse matrices arising from PDE ...
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### Programming Finite Element Methods in C++

I am trying to develop a library for finite element methods in C++ and for that I am looking at the data structures for meshes. Based on what I've read up on fenics and deal.ii, the general ...
536 views

### Efficiency of a Dynamic Mesh vs. a Static Mesh for a Propagating Shockwave

I have a low speed flow with a high voltage discharge occurring within it between two spherical electrodes. We have quite a bit of data from the experiment and have performed 0-D modeling of the ...
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### Flexible Mesh Framework

I am looking for flexible and easy to learn mesh framework which provides data structure for representing and manipulating meshes in 2D i 3D. I've already found a few: MSTK https://software.lanl.gov/...
3k views

### Need a simple mesh format (for FEA) and a tool to generate the mesh

I want to write a 2D FEA code for my course project and I need to import a mesh (2d, simple quad/tri) on a simple geometry such as a L shaped plate or with a square/circular hole in it, something like ...
797 views

### Why dual graph for mesh partitioning

Software such as ParMetis or PTScotch partition a graph. When one wants to use it for mesh partitioning (for example for FEM), a dual graph whose vertices represent cells of the original mesh is ...
192 views

### What is the most efficient approach to interpolate values between two FEM meshes in 2D?

I am looking for efficient algorithm to interpolate values from one unstructured 2D mesh grid to another. Both grids are constructed using the same type of elements (triangles or quadrilaterals). Both ...
173 views

### Flux at coarse-fine mesh grid interface?

I am trying to solve one dimensional inviscid Burger's equation using adaptive mesh refinement. This is the PDE: $$\frac{\delta U}{\delta t} + \frac{\delta F}{\delta x} = 0$$ where the flux F of the ...
501 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? ...
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### Fenics: msh to xml conversion

I generated a mesh file in gambit and wanted to convert it to xml format. I tried the code below, but there is no output. ...
326 views

### Meshes in codes that do AMR

In light of this question and some stuff I read online I am wondering if large FE libs (e.g., deal.ii, libmesh etc.) that do AMR keep the entire mesh or possibly a coarse version of the entire mesh on ...
892 views

### How to discretize Burger's equation?

I am trying to solve the very simple one dimensional burgers equation which is: $$\frac{\delta U}{\delta t} + \frac{\delta F}{\delta x} = 0$$ where the flux F of some variable U is defined as F= \...
133 views

### Convergence rate Jacobi/Gauss-Seidel with mesh resolution

In the book A Multigrid Tutorial - Briggs, Henson. McCormick in the beginning of Chapter 3, it is mentioned that ...because the convergence factor behaves as 1-$O(h^{2})$, the coarse grid ...
115 views

### Where to find CAD and mesh models for tests?

I often find in the literature some numerical tests use CAD and mesh models. I also want to reproduce their results or test my algorithms on those models. But I am not trained to use CAD or mesh tools....
141 views

### Properties of a Shockwave in Fluid Calculations

The comments on the accepted answer of my previous question here have left me with a more general question about accurately capturing shockwaves in fluid calculations. For the sake of having an ...
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### FEniCS: importing mesh along with material and boundary data

Which is the preferred way to import into a FEniCS (python) program a mesh which was generated in an external generator which provides sub-domain and boundary markers? I was using MeshData->...
276 views

### Expanding Winding Number algorithm to arcs

I have a problem that I have been attempting to solve for a few days now. I was wondering if I would be able to get some assistance from the community. In order to detect if a point is in a polygon, ...
196 views

### Once and for all: Which FEM plattform should I use for a very large multiphysics simulation?

I'm fooling around with the decision on how to build a multiphysics simulation for too long now (also several questions in this forum). First, I thought it would be possible/necessary to write most of ...
416 views

### How to “smoothen” (not just refine) a 2D/3D polygonal mesh

Suppose I have a complicated structure given in 2 or 3 dimensions as a polygon mesh. For example, this could represent a "cave" or an assembly of irreguar shaped particles or a tree, whatever. Now I'd ...
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### Survey on automatic structured mesh generation tools

I would like to gain knowledge on available free or commercial tools to generate automatically structured mesh from geometry, particularly quadrilateral. Which options do I have ?
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### Discontinuous Galerkin FEM : Control points are mid-points of edges instead of nodes

I am thinking to use discontinuous galerkin FEM (DGFEM) method to estimate discontinuous displacement field $u: \Omega \rightarrow \mathbb{R}^2$ at the crack surface of a material. The domain is ...
96 views

### Find shortest path around a cylinder represented by 3d triangular mesh

Suppose I have a 3d triangular mesh with the topology of a finite cylinder. Let $C$ be a vertex on that mesh. How can I find the shortest path from $C$ to itself that goes around the cylinder? By ...
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### Smoothness regularisation of a 2D field on a triangular mesh?

I'm working on an inverse problem where the solution is the values of a 2D scalar field at the vertices of a 2D triangular mesh, such that the field can be defined continuously inside the mesh via ...
154 views

### What is the most efficient way to represent a 1D function using $hp$-finite element basis functions

Given a one-dimensional function (let's say infinitely differentiable) and a prescribed accuracy of an L2 (or H1) norm, what is the optimal mesh and (in general arbitrary) polynomial orders on each ...
100 views

### number of tetrahedra in unstructured mesh when edge length is halved

For a given 3D domain, two unstructured tetrahedral meshes M_1 and M_2 are generated. The average edge length in M_1 is double the average edge length of M_2. Are there estimates on the ratio of the ...
191 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 ...
3k views

### Octave 3D mesh, data from file

I have a big file with 3 columns: density, dimension, value. example: 10 0.3 200 10 0.4 300 20 0.3 250 20 0.4 320 ... I am trying to draw a 3d plot - ...
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### How to do local FFT on huge 3D vector data cell mesh and visualize it spatially?

Simulation type: I'm running a simulation with the OOMMF micromagnetics package http://math.nist.gov/oommf/ where are magnet is represented by a mesh of 3 million cells, it gets excited by a ...
568 views

### Quality open source AMR libraries [duplicate]

Possible Duplicate: Is there a general-purpose library for structured grid adaptive mesh refinement? I'm looking for a quality, open source, maintained, scalable automated mesh refinement library ...
436 views

### data structures for efficient/easy implementation of finite volume method for 2D Poisson equation

My question is about implementation alone. Consider a square domain with regular square, cell centred finite volumes. This is for the multiscale finite volume method (Jenny and Lunati) I need to ...
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### Is it possible to retain sets (physical tags) after remeshing the model in Gmsh?

I am currently working on a remeshing algorithm for Abaqus using Gmsh as part of my Bachelors thesis and I seem to be stuck at some point. I am able to remesh .geo and .msh files using the script ...
241 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 ...
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### Creating FEM mesh for image region — what is the most suitable shape function?

I wish to create a FEM mesh to solve an inverse elasticity problem, for an irregular domain. This domain is given by a medical image, so it is discretised and each square on the grid has one scalar ...
278 views

### Getting adjacent cells map for an unstructured polyhedral mesh

I am doing a little project on solving the heat equation using finite-volume method on a solid cube, I converted the polyhedral mesh of the cube to an OpenFOAM mesh. I have a Python code where I ...
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### Sorting Triangle vertices based on indices for alpha blending (back to front) C++, OpenGL

I have implemented in OpenGL alpha blending for a triangle mesh. I render this mesh using a vector of indices that indicate which vertex from a vertices vector should be drawn. The problem is to ...
520 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 ...
133 views

### How to project a 0 genus mesh model on a sphere?

I have a mesh which represents a 0-genus model. My goal is to construct a homeomorphism from that mesh to its bounding sphere. I'm trying to understand a paragraph in http://citeseerx.ist.psu.edu/...
154 views

### Find triangle which contains point on the sphere

Suppose I have a mesh of the sphere (points on the sphere and a triangulation). What is a good and efficient way to find the triangle which contains a point on the sphere (the point does not need ...
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### Modelling rotating machinery other than AMI rotating meshes

I have case of a rotating fan at Low- speed ie about 300-400 rpm. I have successfully carried out RAS simulations using cyclicAMI approach where, the motion of the fan is modeled as rigid body ...
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### Gmsh - dividing a plane surface

How to divide a surface to subdomains, which can be recognized in msh file? Avoiding duplicated nodes is necessary. In general I have geo file which contains definition of smaller and bigger region, ...
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### Coupling Boundary Condition of one PDE with source term of another PDE

We have a system of equations, wherein the BC of one PDE is coupled with the source term of another PDE. We have a regular 2D unit grid in x and y. There are two PDEs to be solved The first PDE (...
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### optimize vertices using a cost function on triangles

I want to optimize the vertex positions in a mesh, with a given cost function on the associated triangles. The paper gives a cost function, which evaluates to an real number by using a sum over the ...
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### Moving airfoil boundary conditions

I am trying to simulate a moving airfoil with constant speed (Mach=0.755, aoa=1.25). I solve Euler equations with Roe's method. I have two boundary conditions: Farfield Slip wall (airfoil) For all ...