I. A. Kryukov

An Approach for Delaunay Tetrahedralization of Bodies with Curved Boundaries

Problem of tetrahedral meshing of three-dimensional domains whose boundaries are curved surfaces is wide open. Traditional approach consists in an approximation of curved boundaries by piecewise linear boundaries before mesh generation. As the result mesh quality may deteriorate. This paper presents a technique for Delaunay-based tetrahedralization in which a set of constrained facets is formed dynamically during face recovery and mechanisms for mutual retriangulation of the curved faces and the tetrahedralization are suggested. The proposed algorithm is constructed in such a way that a facet that was once added in the set of constrained facets is never split into small triangles. It allows retaining the high quality of surface mesh in the tetrahedralization, because during boundary recovery the surface mesh on the curved faces and the tetrahedralization are refined conjointly.

Accretion Flows: Aspects of Gas Dynamic Modeling

We present our view on the application of numerical models to accretion flows in astrophysics. Special attention is paid to the problem of existence of steady-state solutions in time-dependent calculations and to origin of numerically induced instabilities. The problem is considered of the supersonic wind accretion onto gravitating objects. We also present the results of the gas dynamic simulation of accretion on a body imitating the shape of the star magnetosphere with holes in its polar regions. This shape can occur as a result of the cusp disintegration owing to theRayleigh–Taylor instability in the equatorial region of the magnetosphere.