Shock Wave Impact "V" Interface Instability And Turbulent Mixing Studies

Based on the mass fraction model of multicomponent mixture,the Richtmyer-Meshkov instability(RMI)of "V' shaped air/SF6 interface accelerated by weak shock wave was numerical simulated using high resolution finite volume method with minimized dispersion and controllable dissipation(MDCD)scheme.Through the numerical results,we studied the mechanism of the development of instability and the process of material mixing,then summarized some phenomena and laws.When shock wave passed through the“V”shaped interface,the baroclinicvorticity is deposited near the interface due to the misalignment of the density and pressure gradient,leading to the formation of vortical structures along the interface.At the same time,the interface perturbations evolve gradually and lead to the appearance of bubbles and spikes due to Richtmyer-Meshkovinstability(RMI).Focusing on the interface evolution on the earlier stage,this paper summarized the laws of the leftmost interface displacement and interface width growth rate which agree well with experimental results.The vortices which induce the rolling up and deformation of interface interacteachotherandmergegradually.Then,theywill accumulate at several distinct regions,where multi-scale vortical structures are generated because of vorticalinduction.This paper studied this process in detail through turbulent kinetic energy spectrum.The results of turbulent kinetic energy spectrum agree well with the distribution of vorticity.With the emerging of vortical structures with smaller scales in these regions where vortices merging,the turbulent kinetic energy spectrum transfer to sections with higher wave numbers,which means that the structures with smaller scales emerge.The superposition effect of vortex induction makes vortices developing to the wall up and down.Then,the complicated interaction between vortex and wall start.Because of the vortex/wall interaction,vortex was accelerated along the wall,leading to the stretching of material interface.Then,the primary vortex will lifts off from the wall and forms a second vortex.Asthevortex/wall interaction will increase the material mixing significantly,this paper studied the mechanism of this process through material mixing,and analyze the effect of vortex/wall interaction on material mixing quantificationally.It is observed that due to the different scaling with Reynolds number of upper bound and lower bound,an uncoupled inertial range appears,and the mixing transition occurs with the appearance of an inertial range of scales.The classical Kolmogorov-5/3 power laws are shown in the energy fluctuation spectrum,which means the inertial range is just beginning to form and the flow field near the material interface will develop to turbulence.This paper studied the trend of developing to turbulence of the flow field and analyze the process of energy transfer.