Numerical Modeling of Vortex Structures Generation by Converging Shock Wave

This paper investigates the dynamics of high-entropy shock-compressed gas in the vicinity of a shock wave focus, based on the numerical integration of Euler equations in 2D and 3D formulations on moving (focus-converging) grids. A numerical model for a converging shock wave has been developed, implementing the finite volume method on a moving grid using a second-order accurate TVD (total variation diminishing) scheme. A key feature of the developed model is an algorithm that controls the computational grid movement, allowing for the simulation of the shock wave front evolution over a wide range of its radius variations. Calculations are performed for the case of polygonal shock waves in the presence of perturbations that lead to limited cumulation. It is shown that the vortex structure of the flow is significantly influenced by the presence of high-mode perturbations introduced during the generation of a converging shock wave. The presence of such perturbations results in turbulent flow behind the reflected shock wave front. This result can be explained by the generation of vortex surfaces by the perturbed shock wave, emanating from the three-wave configuration lines on the shock front. Intense mixing near the focus of the converging shock wave under symmetry breakdown significantly affects mass and heat transfer processes in the region of the strongest shock-wave compression. Accounting for this factor through numerical modeling is crucial for the development of advanced applications of converging shock waves, such as the initiation of chemical reactions (detonation, shock-wave synthesis).