Information Technologies of Development of Preprocessor of SIGMA Software Package for Numerical Modelling in Continuum Mechanics

The paper covers the area of block-structured adaptive grid generation for finite difference, finite element and finite volume methods. It deals with a problem of development of information technologies and algorithms for generating such grids in complex geometries. Its key idea is to bring together the different existing techniques for computer-aided geometric design of domains, grid generation, grid concentration and grid subdivision. The methods used for a construction of domain geometries, working with block-structured quasi-continuous grids, a subdivision of block-structured adaptive grids into vertex-centered control volumes, generation of ghost nodes and cells, calculation of distances to boundaries are discussed. It is described of the software interfaces of the geometry editor and the mesh generator that were developed in the SIGMA preprocessor. The results of the generation of three-dimensional adaptive grids for the domain of external flow near a hemisphere, flow around a surface of the high-speed aircraft of Falcon HTV-2 type and for the domain of the gap between a wheel and a body of an aircraft are analyzed. The presented methods and algorithms for grid generation have the following advantages: 1. The grids are structured and mesh cells are hexahedra in the entire complex curvilinear computational domain. 2. The grids can be applied for finite difference methods. 3. The grid lines are adjusting with the flow in the whole domain.