REFLECTION OF A WEAK DISCONTINUITY OF THE AXIS AND THE PLANE OF SYMMETRY

In this article we consider the problem of discontinuous characteristic (weak discontinuity) reflection from the axis and the plane of symmetry of the supersonic flow. There is a known problem of perturbations radial focusing when during numerical calculations reflection of a weak perturbation wave from the axis of symmetry leads to an abrupt change in the distribution of dynamics variables along the axis, i.e., to a strong discontinuity, which seems unphysical. By an asymptotic expansion in the vicinity of the axis of symmetry the expression for the intensity of a weak discontinuity was found before the point of intersection with the axis as well as beyond it. It is shown that the appearance of strong discontinuity in the results of numerical calculations is a computing feature, which is a consequence of the difference approximation of the equations. A solution for changes in the intensity of a weak discontinuity as it approaches the axis or plane of symmetry in the plane or axisymmetric supersonic flow was obtained as well.