Would it be possible to have details about the capabilities of this mesher regarding conformal Hex meshing, anisotropy (or stretching) and if it is possible to generate boundary layers that have a good buffer layer of hexahedral elements?
0. Block structured - Key to a good hex mesh for CFD is block structured grids. Within TrueGrid® , one can form any size block structured meshes. The blocks can be connected to other blocks (or not). When they are connected, one can use different interpolation and smoothing features across multiple blocks to form the highest quality interfaces between blocks. Interpolation and smoothing methods can be applied to any faces or blocks (or both). If you are familiar with ICEM or Lawrence Livermore National Laboratory INGRID (these were all developed by the same developer of TrueGrid® , prior to the development of TrueGrid® ), then you already have a sense of the multi-block method used in TrueGrid® .
1. Conformal meshing - In my opinion, this is not the best name for what it refers to. Conformal mapping would indicate that all the elements will be formed using 90 degree angles at the corners. Except for some special cases where the boundary (in 2D) is conformal can we expect a conformal mapping of the interior. For all other problems, the solution is an approximation to a conformal mapping with compromises. This natural limitation has lead to many variations of methods in the field and the literature. In TrueGrid® , we have implemented 4 methods. They are all iterative and you control the maximum number of iterations and the tolerance (which will cause the smoothing process to terminate early if the process has converged). When dealing with CFD models with boundary layers, we recommend the Thomas-Middlecoff method. You can check out this method in the literature. I believe it was published in the mid-1980s. We have made a few minor improvements to their method. It promises to form a nearly orthogonal mesh along the boundary at the expense of orthogonality in the interior. We have gotten good results with this method. It produces (preserves) a boundary layer.
2. Boundary layers - Boundary layers are formed in TrueGrid® using several commands. One class of commands can be used to distribute the nodes along an edge with a bias. It is usually a geometric progression so that the elements are small near the boundary and grow larger as one moves further away from the boundary, but in a smooth fashion. Interior faces of blocks are the result of interpolation and smoothing methods which are at the control of the user. Similarly, blocks are interpolated as a result of the nodal position of the faces. Both interpolation and smoothing can be applied to blocks as well.
3. Projection method - The ramifications of the projection method in TrueGrid® are profound. Two key points should be made with regards to CFD. First, with the projection method, you can use a IGES file for geometry without geometry clean up. This includes not having to reform the surfaces so that you have surfaces that match faces of of your block structure. This cannot be over stated. The savings in time and effort, the advantage in mesh quality, and the simplification in block topology is huge. Secondly, when an edge or face is projected to a surface, it is constrained there. Smoothing does not lift the boundary faces of a block off of the surface. This is because we are using Dirichlet boundary conditions when solving the elliptic PDE's underlying the smoothing method, not the Neumann boundary conditions typical of simpler block structured mesh generators.
4. Automatic verses parametric - TrueGrid® is not automatic. It is, however, highly parametric. One can build a parametric or templet model with TrueGrid® (and many of our advanced users have) so that one can change some of the parameters and rerun the templet file to form a new mesh. The templet file can be constructed to generate a whole class of designs or models, and for that class, TrueGrid® is essentially an automatic hex mesh generator.
