Size gradation control for anisotropic mixed-element mesh adaptation

Metric-based mesh adaptation can be applied to hybrid mesh generation. Using a metric-orthogonal point-placement, a preliminary quasi-structured mesh is generated. Structured elements are then recovered in the most anisotropic areas. To this extent, it is necessary to ensure the smoothness of the metric field in the first place. This is achieved through a gradation correction process, that is the control of the size growth throughout the mesh. The smallest size prescriptions are spread using a metric intersection algorithm. In this paper, we demonstrate the relevance of size gradation control in our metric-based hybrid mesh generation process. Eventually, our goal is to design a gradation correction process that favors the alignment with the metric field, increases the number and improves the quality of the quadrilaterals. Several gradation control strategies are compared to determine which one is best-suited for hybrid mesh generation.