Acceleration rate effects on Rayleigh-Taylor instability in elastic-plastic materials

Rayleigh Taylor instability (RTI) is originally a hydrodynamic instability that can also occur in elastic-plastic (EP) materials. The majority of theoretical and numerical studies on RTI in EP materials assume a uniform and constant acceleration field. However, the applications of RTI in solids (i.e. inertial confinement fusion) occur at variable and impulsive acceleration fields. We have developed a rotating wheel experimental setup that allows for imposing variable acceleration profiles as well as adjustment of the rate of increase in the driving acceleration. In this setup, the test section filled with the soft material (mayonnaise) and air are attached to the disk in such a way that the centrifugal acceleration due to rotation acts on the soft material air interface perpendicularly. In our previous studies, the instability regime for both 2D and 3D initial perturbation geometries were addressed by our group under a linearly increasing driving acceleration. We will present results from our measurement campaign in which we evaluate the effects of the rate of increase in linear driving acceleration profiles for different regimes of RTI. The time evolutions of perturbation amplitude, perturbation mass, and axial stresses acting on the perturbation are analyzed to allow for a better understanding of RTI evolution and aid the development of more comprehensive models for RTI in EP materials.