Research On Key Method And Application Of Visualization For The Complex Geometries Physical Field Based On Adaptive Layered Method

Visualization is an efficient way to handle giant data, with some special advantages such as intuition and understandability, the visualization becomes a convenient means for research and decision-making. Aiming at the difficulty of the visualization for the complex geometries physical field, this dissertation presents a theory of visualization based on adaptive layered Cartesian cut cell method. A new approach to generate the hexahedral amsotropic unstructured Cartesian grids has been developed , the new theories for the numerical simulation and visualization based on unstructured Cartesian grids are presented and two simulation system are developed based these theories.The main work of the dissertation is as follws:Chapter one gives a review and history of the development of the visual ization, the theories and applications of the physical field visualization are discussed. The existing problems are analyzed, and addresses the background, significance and contents of the disseration.Chapter two analyses the characteristic and the typeical errors of the STL files, a brand new vertex merging algorithm based on relaxed AVL tree is presented and the topological structure for STL files is constructed by using the extended corner table structure. Some repair algorithms such as holes & cracks repair algorithm based on splitting rings are developed to achieve the fast and exact repair for STL files.Chapter three introduces a new method to generate the hexahedral anisotropic unstructured Cartesian grids named adaptive layered Cartesian cut cell method (Adaptive layered method). A new topology-based STL files adaptive layered slicing algorithm with special features control strategy is presented to make the slicing process accurate and efficient, and a solid regions judging approach based on spatial relation contour tree is applied. To overcome the disadvantage of the point-in-polygon algorithm to identify the inside and outside background mesh vertices, a new points-in-polygon method is employed using the convex hull to judge the enclosure relation. Finally, a Cartesian grids adaptive anisotropic refinement algorithm is used to gain the high quality anisotropic unstructured Cartesian grids.Chapter four presents a variable step implicit FDM method for numerical simulation of temperature field, the numerical simulation of temperature field for press die casting has been done using this method. Also in chapter, the region EIA diffusion calculation models based on anisotropic unstructured Cartesian grids are presented, and the atmosphere and water region EIA are achieved.Chapter five analyzes the casting defects for die casting, and presents a new mathod for simulation and forecast on casting defects based on statistical data. On the basis of temperature field numerical simulation and the structural analysis,a new...