On the difference approximation of gas-dynamic flows on the free boundaries of the computational domain

The paper presents a technique for constructing non-reflective boundary conditions based on local one-dimensional approximation of gas-dynamic flows using data obtained by extrapolation along a streamline. The technique is focused on obtaining the correct values of variables on the free boundary of the region, mainly in two-dimensional and three-dimensional formulations. The work also considers a method for implementing non-reflective boundary conditions based on a homogeneous linear differential transport equation with adjustment of variables in accordance with the characteristic form of the gas dynamics equations.