Richtmyer-Meshkov-induced turbulence in shock-tube experiments

Experiments of the Richtmyer-Meshkov instability are carried out in a vertical shock tube to investigate the effect of initial conditions on the late-time turbulence and mixing. An initially 2D perturbed interface separating a light fluid from a heavy fluid (air from SF₆, Atwood number A ≈ 0.6) is first accelerated by the passage of an incident shock (of Mach number M_s ≈ 1.15 and M_s ≈ 1.25), followed by reshock. State-of-the-art diagnostics are used to measure the density and velocity fields simultaneously at four different downstream visualization windows past the initial shock (3 before reshock, 1 after reshock). Typical quantities characterizing the time evolution of the instability are measured, such as the perturbation amplitude, x-t diagrams, and vorticity fields. At each window, the shots are repeated multiple times at a high-repetition rate (∽ 100 shots per window), providing a unique ensemble data set used to obtain turbulence statistics.