A three-dimensional simulation on deformation and instability of low-density spherical bubble induced by incident and reflected shock waves is performed with Navier-Stokes equations.A computational model validated by experiments is used to study deformation of bubbles,formation and three-dimensional instability of vortex rings.It is found that low.density spherical bubbles can deform and form vortex rings with different rotating directions along streamwise direction induced by incident and reflected shock waves. Baroclinic effect is the main reason for formation of vortex rings.Vortex rings move due to self-induced effect and flow field velocity. And azimuthal instability OCCURS due to disturbance.Finally.vortex rings may induce turbulent flow a8 they form a complicated structure dominated by small-scale streamwise vortices.

A variable-density stochastic vortex model is used in simulating H₂/O₂/N₂ turbulent jet diffusion flames,in which turbulence is modeled by vortex sample,vortex suppression and vortex turnover.A large-vortex suppression mechanism for variable density reacting flows is presented and effects of parameters in model prediction are discussed in detail.It shows that the modified model can predict reasonably H₂/O₂/N₂ jet flame structures,and reflect characteristics of turbulent vortices.It also reveals that various parameters in vortex sample and vortex suppression affect results of the model.