Parallel three-dimensional LAD model on Cartesian grids of nested structure

This preprint addresses a generalization of the technology of nested-type Locally Adaptive (LAD) Cartesian grids to the three-dimensional case and a description of the corresponding software library. The library is written in C++ programming language using object-oriented programming principles and is adapted for parallel computing on multi-core shared memory processes with the OpenMP application interface. The library takes into account the specificity of multi-threaded Cartesiangrid calculations of 3D problems. This can significantly minimize the usage of computer memory by avoiding the storage of grid information. Data grid as the coordinates of the nodes, normals, areas, and volumes are not stored, and are evaluated as needed. The order of cell traversing is represented by a special list, which simplifies parallel implementation by means of the OpenMP directives. This preprint contains a description of tree-like data structure on the LAD grid, the basic principles of the discrete model, and main functions of the library developed. Preliminary results of testing the library and the estimation of the effectiveness of parallel calculations are given for calculations of the problem of the evolution of an explosion in a closed space.