Shock waves dynamics and evolution of vortex formation during the interaction of spherical air pulse with aqueous foam layer

The numerical study of the powerful air spherical shock-wave pulse interaction with the protective aqueous foam barrier with the initial liquid volume fraction of 0.2 is carried out. The foam layer thickness is selected to satisfy the condition of the non-reflection of compression wave from the foam external boundary at the considered time intervals. In studying the wave flows dynamics, we used the assumption of the foam structure destruction into the microdrops suspension behind the strong shock wave front. The two-phase medium is described on the basis of the gas-droplet mixture model, which includes the laws of conservation of mass, momentum and energy for each phase in accordance with the single-pressure, two-speed, two-temperature approximations in a two-dimensional axisymmetric formulation. The Schiller–Naumann model is used for taking into account the interfacial drag forces. The contact heat transfer influence at the interface between the phases is taken into account by the Ranz–Marshall model. To describe the properties of air and water, the Peng–Robinson and perfect fluid equations of state are used. The numerical implementation of the model is carried out using the OpenFOAM open-source software with the two-step PIMPLE algorithm. The numerical study results are presented as spatial distributions of pressure fields, velocities and streamlines. The significant attenuation of the spherical shock wave intensity during its interaction with the aqueous foam layer has been established. The causes and dynamics of the toroidal vortices series formation in the gas region behind the shock front are investigated. The results reliability is confirmed by comparison with the solutions of the similar problem, found by another numerical method.