The most appealing property of the mapped mesh for this model is the extremely good control it provides over element size, quality, and growth rate - even though it can require some work to prescribe the optimal distributions on all edges.Ī mapped 2D mesh for the NACA 0012 airfoil model. Mapped meshes can be particularly powerful for 2D simulations, such as the NACA 0012 airfoil benchmark shown below. Mapped mesh on one surface of the solar panel model. The fact that all elements have 90° angles means that the elements have no skewness at all. The anisotropy is obtained by using Distribution nodes, which contain settings to control the number of elements and their distribution along the edges.
The mapped mesh is refined so that we obtain finer elements close to the free edges and smooth transitions to the fine meshes covering the beams. The figure below shows a high-quality mapped surface mesh for one of the panels in the solar panel model. Mapping has the potential to create the very best surface meshes. Therefore, we don’t need to mesh all edges before we mesh a face and volumes can be meshed without meshing all the enclosing faces first. A Free Triangular feature, for example, meshes both its designated faces as well as all adjacent edges and points that were not meshed previously. Note that a tool that meshes entities of a certain dimension also meshes adjacent entities of lower dimensions. We can start by discussing options for surface meshing, since we recommend to mesh faces first to verify adequate resolution and a high element quality. Meshing Tools for CFD Modeling in COMSOL Multiphysics®ĬOMSOL Multiphysics provides a wide selection of tools to control and generate mesh.
Using the mesh-controlled domain behind the car and the partition face shown in the first part of this blog series, the total number of elements can be approximately kept constant, but with much better resolution in the wake. So, the mesh could be finer behind the car and it is unnecessarily fine far downstream of the car.
However, we can see that the mesh-controlled domain behind the car hasn’t resulted in any finer mesh and the unstructured mesh covers the whole wind tunnel. It is perfectly possible to solve the Ahmed body problem with the mesh shown above. The physics-induced mesh can sometimes be sufficient for simple models and is always a good starting point for more advanced meshing. The boundary layer mesh on the no-slip walls is also visible. We can see that the mesh is finer on the walls than in the volume, and even finer close to sharp edges. Boundary Layers 1 subnode adds boundary layer mesh to all no-slip boundariesĪ zoomed-in view of the mesh resulting from the physics-induced meshing sequence for the Ahmed body model.Free Tetrahedral 1 subnode creates the actual mesh on both boundaries and in domains.Corner Refinement 1 subnode automatically identifies all sharp-enough angles internal to no-slip walls and prescribes an even finer mesh along such edges (in this case, it finds most of the sharp edges on the car, except for the one connecting the roof and the slant).Size 1 subnode is active on all no-slip walls and prescribes a somewhat finer mesh there.Size subnode contains a set of mesh size parameters that depend on the property settings and the bounding box of the geometry.The physics-controlled meshing sequence for the Ahmed body model, which we also used in the previous blog post, looks like this: This controls the size scale of the elements.Walls, for example, can induce finer meshes and boundary layer meshes.A turbulence model with automatic wall treatment, for example, gives finer mesh than a laminar flow model.Such a sequence depends on the following aspects:
In this follow-up blog post, learn about physics-controlled meshing, adaptive mesh refinement, and how to use a variety of meshing tools in the COMSOL Multiphysics® software for your fluid flow simulations.Īfter setting up the flow conditions for a fluid flow model, COMSOL Multiphysics enables us to invoke physics-controlled meshing sequences. We have already discussed the factors that make a high-quality mesh and how to prepare a CFD model geometry for meshing.