Interactive Geometric User Environment For Numerical Simulations

Many physical phenomena in engineering and scientific computations can come down to solving partial differential equations by establishing reasonable models. The solution of these complex equations frequently appeals to numerical methods with the steady improvement of computer science and computational mathematics. Numerical simulations have been widely used in the fields of structural mechanics, fluid dynamics, electromagnetics, aeroacoustics, manufacturing optimization, and etc. EEMAS is a numerical simulation environment for large scaled scientific computations. Various application software collaborate to solve multidisciplinary computational simulation problems jointly. It provides a comprehensive numerical simulation capabilities including geometry modeling, geometry repair, meshing, grid analysis, numerical solving, visualization, and etc.An unstructured grid based interactive geometric user environment, i.e. Geometry-Handler, is developed in this paper. It is a sub-environment of EEMAS and provides sophisticated graphical user interfaces with unstructured grid-oriented geometric handling capabilities for geometry modeling, geometry repair and validation, and meshing.A B-Rep representation for geometries is implemented in Geometry-Handler. With respect to mathematics, the curves and surfaces are treated as cubic splines and bi-cubic surfaces, respectively. The topologies of 2D geometries consist of points and curves, and those of 3D geometries consist of points, curves, loops and surfaces. Based on such a CAD kernel, a visual operating environment for geometric model creation and manipulation is also implemented in Geometry-Handler.Geometries translated from CAD systems must be repaired and validated before meshing to meet some special restrictions and analysis requirements in the aspects of topologies and geometric shapes. Geometry repair and validation modules in Geometry-Handler are discussed. Topology relationship specification and surface reconstruction methods are analyzed in detail.The grid oriented interactive module is designed and realized. Issues of unstructured meshing, grid intensity control, and grid quality analysis are discussed in detail. Grid intensity control is an important aspect of grid generation, and implemented in Geometry-Handler by means of the background grid and point sources, line sources and triangle sources.