Instability, mixing, and transition to turbulence in a laser-driven counterflowing shear experiment

Abstract

In a turbulence experiment conducted at the Omega Laser Facility [Boehly et al., Opt. Commun. 133, 495 (1997)]], regions of 60 mg/cc foam are separated by an aluminum plate running the length of a 1.6 mm shock tube. Two counter-propagating laser-driven shocks are used to create a high speed, ΔV=140 km/s shear flow environment, sustained for ∼10 ns, while canceling the transverse pressure gradient across the interface. The spreading of the aluminum by shear-instability-induced mixing is measured by x-ray radiography. The width of the mix region is compared to simulations. Reynolds numbers ≳4×105 are achieved within the layer. Following the onset of shear, we observe striations corresponding to the dominant mode growth and their transition through non-linear structures to developed turbulence.