I’m trying to generate a mesh from two txt files ( nodes.txt and elements.txt ) using the tool FEM_TO_GMSH - Convert Triangulation to GMSH File . nodes.txt is a list of nodal coordinates, elements.txt is the connectivity. However, the mesh consists of triangles embedded in 3d and this routine only w…

Have you tried to use mesheditor? [image] L-shape mesh generation with right element mesh The link above showed how to make it for a single cell. In this post I’ve now added a simple L-shape mesh with “left” diagonals. import matplotlib.pyplot as plt from dolfin import * …

Hi @dokken , Yes, the mesheditor is really easy… on the surface. Unfortunately, it reorders my nodes in a way that messes up the cell orientations (see attached). If I set close(order=False) I obviously get an UFC error. Is there any way to get around this? [image] from dolfin import * import nu…

Dolfin needs to order the mesh to be able to work with high order function spaces. Why not use order=True? What do you Need the ordering for? As a slight tangent, you can see the effect of ordering a mesh here: Cell node labeling - #2 by dokken

Ok I see, the nodes were ordered (“upstream”) to produce a consistent outward oriented normal. I do something like this to get my (non-unit) normals: J = Jacobian(mesh) G1 = J[:,0] G2 = J[:,1] G3 = cross(G1, G2) Is there another way to achieve this?

As your mesh looks like a sphere, you can easily use geometric information to adjust the normals. Lets say the center of your sphere is at c[0], c[1], c[2]. J = Jacobian(mesh) G1 = J[:,0] G2 = J[:,1] G3 = cross(G1, G2) c = as_vector([[0,0,0]]) x = SpatialCoordinate(mesh) r = x-c n = G3*dot(G3, r) …

Unfortunately I don’t think that works for me. For example if modeling a surface pressure load (psuedo code): V = VectorFunctionSpace(mesh, 'CG', 1, dim=3) u = Function(V) v = TestFunction(V) gsub1 = Gsub1 + u.dx(0) gsub2 = Gsub2 + u.dx(1) gsub3 = cross(gsub1, gsub2) # Deformed normal f = dot(v, gs…

(The code snippet assumes a geometric dimension =2 so doesn’t really apply in this case)

Mesh from txt of coords and connectivity

dokken July 29, 2021, 7:55pm 2

Have you tried to use mesheditor?

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Mesh from txt of coords and connectivity

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