Mesh quality is where the CFD analyst has the largest impact on solution quality - after all, the numerical algorithms and physical models are dictated by choice of the solver. A high quality mesh increases the accuracy of the CFD solution and improves convergence relative to a poor quality mesh. Therefore, it's important for a mesher to provide tools for obtaining and improving a mesh. Some meshing software uses hundreds of unnecessary blocks as a crutch to obtain a decent mesh. Gridgen's mesh methods, on the other hand, have been honed through years of application on analyses for which accuracy, and hence mesh quality, are critical.

+ F-18 Engine Compartment

Gridgen uses the "bottom-up" approach to meshing in which curves are created first, followed by surfaces and then volumes. This approach is contrasted with the "top-down" approach in which the analyst is presented with a collection of volumes that must be whittled and mapped to the CAD model. The bottom-up approach provides significant flexibility in meshing strategy whereas the top-down approach is notorious for limiting topology choices and leading you into dead-end topologies that cannot be completed. Bottom-up also gives you ultimate control over mesh clustering and placement near the boundaries where it's most important.

You are provided with many diagnostic tools in Gridgen to ensure that mesh quality criteria are met. Cell size, cell-to-cell size variation, aspect ratio, Jacobian, skewness, smoothness, and boundary resolution can all be examined graphically. This examination may be performed locally (looking at the values in each individual cell) or globally (showing only cells that don't meet user-defined criteria). These quality diagnostics are also closely integrated with the mesh methods so quality may be monitored as the mesh is being generated.

+ Americas Cup Yacht Keel