A new instability of a contact surface driven by a nonuniform shock wave

Propagation of a nonuniform shock wave driven by a ripple piston has been investigated both analytically and computationally. Oscillating surface ripple of the shock wave is found to decay exponentially with its propagation. The oscillation period and the decay time observed in simulations agree very well with the linear theory. A new instability of a contact surface is shown to be driven by the ripple shock wave. Namely a uniform contact surface becomes unstable after the nonuniform shock passing through it. The growth rates depend on the phase of the oscillating shock wave at the time when the shock hits the contact surface. Physical mechanism of the instability is qualitatively discussed. Nonlinear evolution of the instability is also investigated. Properties of the instability are quite different from those of the Richtmyer-Meshkov instability in both linear and nonlinear phases. copyright 1996 American Institute of Physics