Effect of multi-mode initial conditions in shock-driven flows

Carefully imposed initial conditions have been shown to control late time turbulence and mixing in buoyancy-driven flows [\textit{Dimonte et al., 2004; Banerjee {\&} Andrews, 2009}]. This is important in understanding and prediction of Inertial Confinement Fusion. We report the experimental results on the initial condition parameters, namely amplitude ($\delta )$ and wavelength ($\lambda )$ of perturbations, that impact the material mixing and transition to turbulence in shock-driven, Richtmyer-Meshkov instability. A detailed study on the impact of $\delta $ and $\lambda $ on turbulence in a heavy gas varicose curtain (air-SF$_{6}$-air) is undertaken. Experiments were conducted with stable, membrane-free initial conditions at shock Mach number, \textit{Ma} = 1.2 and Atwood number, \textit{At }= 0.67. The effect of multi-mode initial conditions on mixing and transition was quantitatively measured using simultaneous Particle Image Velocimetry (PIV) and Planar-Laser Induced Fluorescence (PLIF). The turbulence statistics were measured for different combinations of $\delta $, $\lambda $. The results obtained are being compared with data from ongoing 3-D numerical simulations.