Mesh Topology

A key component of Ennova’s solution is a technology we call mesh topology. The mesh topology is the foundation upon which both geometry healing and grid generation operate. It allows Ennova to heal, defeature and generate grids while guaranteeing that all of the nodes lie on the original CAD data and all important features are maintained. The mesh topology allows Ennova to generate structured anisotropic meshes in critical areas such as blade leading and trailing edges, as well a swept blocks for narrow tip clearences.

Mesh Topology is a software layer that lies between the raw CAD data, the geometry cleanup, and meshing algorithms. This layer serves multiple purposes. It allows Ennova to treat the original CAD geometry as read-only even while it repairs the same geometry. It also allows the meshing algorithms to construct geometric objects like swept regions and structured regions that do not correspond to any CAD entity. The mesh Topology can be obtained through STL or NURBS data. For NURBS data the CAD topology can be obtained directly from the CAD data. This can be a very powerful tool for creating hybrid meshes. Often the parametric surface from the CAD is constructed in a very physical manner. Consider for example a 3d aircraft wing that has been constructed by lofting multiple 2D airfoils. Here the u and v direction of the parametric surface will basically align with the flow and spanwise directions respectively. Ennova can automatically recognize this topology and place a structured surface mesh on this topology. It will automatically refine the leading edge based on curvature and stretch the prism elements in the spanwise direction. Special algorithms have been developed to connect the anisotropic prism mesh to the background isotropic tetra mesh. If NURB data is not available and STL data is used, Ennova will automatically repair minor defects in the data such as tiny triangles, holes, and self intersections. After which it will use curvature requirements to segment the model and find its natural topology. Whether the topology is extracted from the CAD or STL it is important to note that the entire repair happens at the topology level. The CAD data is never modified. Once the topology is meshed, the final mesh always is projected back to the original surface data. An Ennova mesh always represents the original geometry not a smoothed, fixed approximation of it.