Conformal Refinement and Coarsening of Unstructured Hexahedral Meshes

This paper describes recently developed procedures for local conformal refinement and coarsening of all-hexahedral unstructured meshes. Both refinement and coarsening procedures take advantage of properties found in the dual or “twist planes” of the mesh. A twist plane manifests itself as a conformal layer or sheet of hex elements within the global mesh. We suggest coarsening techniques that will identify and remove sheets to satisfy local mesh density criteria while not seriously degrading element quality after deletion. A two-dimensional local coarsening algorithm is introduced. We also explain local hexahedral refinement procedures that involve both the placement of new sheets, either between existing hex layers or within an individual layer. Hex elements earmarked for refinement may be defined to be as small as a single node or as large as a major group of existing elements. Combining both refinement and coarsening techniques allows for significant control over the density and quality of the resulting modified mesh.

Growth of Buried CoSi2 Layers in Si(100) by Molecular Beam Allotaxy

ABSTRACTBuried single crystalline CoSi2 layers in Si(100) have been grown using molecular beam allotaxy. In this paper, we investigated the diffusive interaction of two buried silicide precipitate layers, one with a small Co peak concentration of 10 at% and another one with 26 at%. Annealing causes first local coarsening in each layer, and then dissolution of the thinner precipitate layer. The accumulation of the Co atoms at the thicker layer is described by a simple model for the diffusional redistribution.