Theoretical analysis of effects of viscosity, surface tension, and magnetic field on the bubble evolution of Rayleigh-Taylor instability

The evolution of bubble in Rayleigh-Taylor (RT) instability for non-ideal hydromagnetic fluid is investigated theoretically in this study. In a plane perpendicular to the magnetic field, the general governing equation describing the bubble evolution is derived by considering the influences of viscousity, surface tension and magnetic field. The numerical and asymptotic solutions of the bubble velocity in two-dimensional planar geometry are obtained under different conditions and the effects of fluid viscosity, surface tension and magnetic field on the bubble growth are then analyzed in detail. It is found that the bubble velocity is reduced by viscosity and surface tension, which indicates that viscosity and surface tension can suppress the RT instability. It is also observed that the influence of magnetic field on the RT instability is caused by its nonlinear part, and whether the RT instability can be suppressed or enhanced depends on the direction of the nonlinear part of magnetic field.