CUBIT is not open source (and although not expensive compared to commercial software, acquiring a license takes a long time), but produces high quality meshes and can be linked into other applications.The site says that the source is available under GPL upon request. From what I can tell, it is an interactive environment rather than a library. LBIE generates quad and hex meshes from volumetric data.You can download the source through the link above, but it is not ready for production use yet. The Jaal component of MeshKit (LGPL) is based on recombination similar to Q-Morph above, read the IMR-2011 paper for more details.Gmsh (GPL with linking exception) can generate quad meshes using a recombination algorithm described in this paper.I know of two open source free-quad meshers: Some open source tools have built-in smoothing facilities and the LGPL-licensed Mesquite package is designed as a library specifically for mesh quality improvement. Note that smoothing is necessary for both approaches, sometimes with alternating topology fix-up and smoothing steps. ![]() Q-Morph is an example that is used by ANSYS. triangles) and then produce an all-quad mesh through recombination and/or further decomposition. Indirect methods generate some intermediate decomposition of the domain (e.g. The Paving paper is a standard reference and is the method used by CUBIT, so you have seen these meshes in many publications. If we want to close our cylinder we need to go back to Geometry > Add > Plane Surface, and if we need a Volume, as long as you have a closed domain you can go to Geometry > Add > Volume and finalize the solid cylinder.The are essentially two approaches to free quad meshing:ĭirect methods generate a quad mesh directly, usually by some advancing front method. Furthermore, we see that there have been generated 4 surfaces in addition to the bottom surface we initially generated when creating the circle. Evidently, the numbering is a little odd as automatically there will be overlapping lines and surfaces which will be removed to avoid duplicates. The way the extrusion labels the lines is: top, right, left. The first line we selected to be extruded was line 1, and that gives us a pattern that will be useful whenever we are creating more complicated geometries that need to be parametrized. So far we have created all geometries by entering numbers one by one in our text editor but here we have used the GUI. Note that the blue numbers represent the line labels and the gray ones the surfaces. Here we’ll see a couple of interesting facts. Let’s extrude the lines that define our circle: You can extrude: Points, Lines and Surfaces, creating Lines, Surfaces and Volumes respectively. Depending on our modeling end goal, there are different types of extrusion. Going back to the circle example, we could just extrude it and create a cylinder. In 3D we will find other features useful such as: Translate, Rotate, etc. So far we have covered most of the features under Add in the Geometry node. It’s clear that the volume has been created when we select the Sphere to be a solid and will be described by Volume 30, which we have defined in our. How can we know for sure that it is a solid volume? Go to the top menu, click Tools > Visibility and a window with all the defined Elementary Entities will pop up. Now, in Gmsh you only see line and surfaces even if you have created a volume. Finally we can create a volume, which in this case will be our solid geometry. The Line Loop feature groups all the lines, which in this case are defined by the Circle (arches), and then to create the surfaces, we use the Ruled Surface feature which is meant to create surfaces from curved geometries. The first part of the script will be omitted as it’s the same as the one found in the circle. Whenever we work in 3D, we can work with a solid domain or just with a shell surface. Halving it from 72 reduced the conversion time by 60 for most of my stp files. The factor that most effected the conversion time was MinimumElementsPerTwoPi. I have adjusted the CharacteristicLengthMax from 25 to 10, but this showed no reduction in conversion time. dat file:Īs we see above, we have also included another flag. I am trying to create an STL from a STP file using the following options. In the sphere case we can use the very first version of our circle as we will only need to create two additional points to create 3 intersecting circles. This way we will showcase how to create a sphere. We will start with the circle we have created in our previous post “ Basic 2D Geometry Creation Using Gmsh“. ![]() Although, we have already covered the fundamentals of 2D geometries with Gmsh and the generation of the 3D geometry is quite similar (or identical), I want to mention a couple of attributes that might be of interest when modeling unbounded domains, i.e. This basic tutorial covers 3D geometries.
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