Numerical Study On The Richtmyer-Meshkov Instability Of The Minimum-Surface Featured Interface Impacted By Shock Wave

Richtmyer-Meshkov(RM)instability phenomenon refers to the interface instability of fluid with a certain density gradient after being impacted by shock waves.Under the effect of baroclinic vorticity and pressure disturbance,the interface disturbance increases continuously,asymmetric spikes and bubbles appear,and the fluid flow eventually develops into turbulence.The study on RM instability not only promotes the development of compressible turbulence and vortex dynamics,but also plays an important role in inertial confinement fusion,supersonic combustion and supernova explosion.In the development of RM instability research,two-dimensional(2D)research has always been the mainstream and fruitful research results have been achieved.However,in practice,the RM instability often exists in three-dimensional(3D)forms.The minimum-surface featured interface is a special 3D interface with zero mean curvature,which can be used as an ideal interface to study 3D RM instability.It is of great significance to study the minimum-surface featured interface impacted by shock waves,reveal the underlying evolution mechanism and a series of scientific problems brought about by multi-mechanism coupling.In this paper,the Level Set method is used to numerically study the interaction between the shock wave and minimum-surface featured interface,the influence of different interaction mechanisms on interface evolution is analyzed.It is aimed to lay a foundation for subsequent researches.The following works are conducted in the present study.1.The formation mechanism of the lagging structure in the previous experimental results is revealed in the study of a heavy/light minimum-surface featured interface impacted by a planar shock wave.By extracting the 3D wave systems and velocity field distributions,it is found that the irregular shock reflection at the interface significantly affects the distribution of soap fog in the flow field.After the shock wave impacts the gas interface,the soap fog formed by the soap film breakup is divided into two areas by the airflow.One part moves to the observation window,while the other part flows to the middle part of the 3D space forming a lagging structure.This process reasonably explains the formation of this lagging structure.2.In the study of the light/heavy minimum-surface featured interface impacted by a reshock,the effects of initial interface height,incident shock intensity and shock reflection distance on the interface evolution are investigated.It is found that there is irregular shock reflection occurring at the gas interface after the re-shock,an arc-shaped high-pressure region pushes the interface to promote the phase inversion.The interface mixing zone width growth rate is greatly affected by the incident shock wave intensity and is almost independent of the interface height and reflection distance,which verifies the validity of Charakhch’yan reflection model.3.In the study of a planar shock wave interacting with heavy gas layers,it is found that the interface coupling effect and the wave reflection between the two interfaces have important influences on the evolution of the whole heavy gas layer,the interface amplitude increases intermittently.The wave system formed in the gas layers is complex due to the special 3D curvature of the minimum-surface featured interface.The existing theoretical models fail in predicting the growth of interfacial disturbance,which indicates that it is necessary to develop a new theoretical prediction model to fully consider the 3D effect of the gas layers.