Development of Initial Perturbations in the Problem of Motion of a Cylinder in Circulation Flow

The stability of a cylinder in circulation flow of an inviscid incompressible fluid is considered. The investigation of stability in the simple two-dimensional system is of considerable interest since in this problem the analytical solution can be obtained in both spectral and initial problems. The investigation of the critical layer region in which the phase perturbation velocity coincides with the velocity of mean flow is of particular interest since just in this region the perturbations are concentrated and grow indefinitely.