Mesh Enhancement adds element layers along all fluid-wall and fluid-solid interfaces. It augments the original mesh to produce a smooth distribution along all walls, which is critical for accurate flow and temperature prediction. Mesh Enhancement ensures adequate mesh across small gaps, which can be very difficult manually.
Mesh Enhancement creates layers before the 3D mesh is constructed. Diagnostic algorithms detect and avoid element clashes in small gaps automatically. Element layer height across each surface is uniform, and is based on the smallest length scale on a surface. Gradual transitioning between surfaces ensures gradual variations in element height throughout the model.
Layer uniformity is important for accuracy in certain analyses. Examples include flows in which the turbulence is very sensitive to the flow near the walls and within long, narrow channels. In the latter case, meshes that have been enhanced have been shown to be significantly less disruptive than non-enhanced meshes to the flow near the walls, resulting in improved flow uniformity throughout the channel.
Controls the layer thickness. The layer height is determined by multiplying this factor by the local isotropic length scale for that surface. Reduce this factor for thinner layers and reduced total thickness.
Because Mesh Enhancement layers are constructed prior to the 3D mesh, changing certain analysis settings after the mesh has been generated will require the entire mesh to be regenerated. If the analysis is continued from a saved iteration or time-step, the results are mapped to the new mesh.
An extension of Boundary Mesh Enhancement, Automatic Layer Adaptation is useful for high speed aerodynamic flows where the distance between the near-wall node and the wall-node is critical for accuracy. This is ideal for external flows such as vehicle aerodynamics and hydrodynamics, but is not so useful for slower speed internal flows.
After iteration 37, the Y+ values throughout the model are inspected at every iteration. The nodes nearest the walls are moved closer to drive the Y+ values within the optimum range for turbulent flow. There is only a slight time penalty for this adjustment scheme.