Richtmyer-Meshkov instability

  The Richtmyer-Meshkov instability (RMI) occurs when an interface between fluids of differing density is impulsively accelerated, e.g. by the passage of a instability begins with small amplitude perturbations which initially grow linearly with time. This is followed by a nonlinear regime with bubbles appearing in the case of a light fluid penetrating a heavy fluid, and with spikes appearing in the case of a heavy fluid penetrating a light fluid. A chaotic regime eventually is reached and the two fluids mix.