Focusing of an oscillating shock wave emitted by a toroidal bubble cloud

Formation and Amplification of Shock Waves in a Bubble “Cord”

“…A certain analog of experimental modeling of the problem in this formulation was studied in [5], where a polyurethane-foam sphere saturated by a gas was used as a cluster. By means of numerical simulation of shock-wave interaction with a toroidal bubble cluster placed onto the centerline of a hydrodynamic shock tube, it was shown [6] that generation of a toroidal wave by a bubble cluster leads to emergence of directed emission toward the liquid. Another example of wave focusing in axisymmetric geometry was considered in [10], where the problem of a hydrodynamic shock tube with abrupt changes in the cross-sectional size and filled by a chemically active bubble mixture was numerically studied.…”

“…Beginning from publications of 1960s-1970s (see the references in [1, Chapters 5 and 7]), this model was used to describe the development of cavitation in the case of underwater explosions near the free surface, the strength of a real liquid containing cavitation cores, and the structure of shock waves and rarefaction waves and their interaction in passive [4,6] and chemically active [10] bubble media in both one-dimensional and two-dimensional formulations. A comparison of shock-wave processes and the dynamics of state and the structure of bubble media calculated within the framework of this model with experimental data showed that the IKW model and its modifications offer an adequate description of both the wave processes in passive and chemically active bubble media and the dynamics of the medium structure.…”

“…Among various problem formulations in this field, let us note the experimental and numerical research of explosions of cord high explosive (HE) charges and non-one-dimensional flows with axial symmetry [1][2][3][4][5][6] in free bubble media. In particular, the results for a number of problems of an underwater explosion with a detailed analysis of the structure and parameters of the wave field of cord and spiral charges, specific features of transformation of shock waves in bubble media, their amplification due to collisions and focusing, and also the problems of formation of bubble detonation waves in chemically active systems are described in [1].…”

Shock Waves in Bubbly Media

“…Bubbly media can also be effective, because as we showed, they can amplify shock waves by orders of magnitude. Below we will consider the so-called free bubbly systems in two statements, which amplify the outer disturbances and enable certain concentration of the radiation in a given direction [56,57].…”

“…The statement with the toroidal bubbly cluster was first proposed and studied in [56]. The objective of the study was to access the efficiency of this method for the generation of strong shock waves in a liquid and for their directional radiation prior to proceeding to the experimental arrangement.…”