Numerical simulations of the Rayleigh-Taylor instability in accelerated solids

Abstract

The classical Rayleigh-Taylor (RT) instability is developed in the interface that separates a heavy fluid from a lighter one in the presence of a gravitational field. If the interface is not perfectly planar, its small perturbations will grow without bound. When a solid is submitted to a very high acceleration, for example by the application of an external pressure on one of its faces, this interface is also RT unstable. This kind of situations are found in several technological applications like explosive forming process, laser implosion of fusion targets, electromagnetic implosion of metal liners or experiments to achieve hydrogen metallization [1]. If the RT instability appears the experiment could fail. So it is important to study which are the mechanisms that produce stabilizing effects to alleviate the growth of the instability. When we are dealing with fluids the stabilizing mechanisms are, for example, gradient effects, viscosity and superficial tension. Dealing with solids, their intrinsic properties can produce such a stabilizing effect. In a very simple interpretation, the elastic forces that the solid develop can compensate the buoyancy force that leads the instability, but when the material plastifies it can again be unstable.