The Richtmyer-Meshkov instability of a “V” shaped air/helium interface subjected to a weak shock

Abstract

The Richtmyer-Meshkov instability of a “V” shaped air/helium gaseous interface subjected to a weak shock wave is experimentally studied. A soap film technique is adopted to create a “V” shaped interface with accurate initial conditions. Five kinds of air/helium “V” shaped interfaces with different vertex angles (60°, 90°, 120°, 140°, and 160°), i.e., different amplitude-wavelength ratios, are formed to highlight the effects of initial conditions, especially the initial amplitude, on the flow characteristics. The interface morphologies identified by the high-speed schlieren photography show that a spike is generated from the vertex after the shock impact, and grows constantly with time accompanied by the occurrence of the phase reversal. As the vertex angle increases, vortices generated on the interface become less noticeable, and the spike develops less pronouncedly. The linear growth rate of the interface mixing width of a heavy/light interface configuration after compression phase is estimated by a linear model and a revised linear model, and the latter is proven to be more effective for the interface with high initial amplitudes. It is found for the first time in a heavy/light interface configuration that the linear growth rate of interface width is a non-monotonous function of the initial perturbation amplitude-wavelength ratio. In the nonlinear stage, it is confirmed that the width growth rate of interface with high initial amplitudes can be well predicted by a model proposed by Dimonte and Ramaprabhu [“Simulations and model of the nonlinear Richtmyer-Meshkov instability,” Phys. Fluids 22, 014104 (2010)].

Numerical study of the Richtmyer–Meshkov instability of a three-dimensional minimum-surface featured SF6/air interface

“…From 200 μs to 250 μs, except the growing of the interface amplitude, a salient feature of the experimental images is the detachment of the gas interface and the soap film. As has been proved in a series of previous studies, 23,47,48 the soap film, once impacted by a shock wave, ruptures and atomizes immediately. It exerts very limited influence on the later flow field.…”

“…This kind of detachment can be observed frequently in heavy/light gas interface scenarios. 18,23 Interestingly, seen at 400 μs, distinct lagging structures (S1, as highlighted by white dashed squares) are formed. In our previous study, 36 we believed that S1 was caused by gas interface deformations, the present numerical results deny our previous judgment.…”

Statistical characterization of a shock interacting with an inclined gas column

“…(2019) and V-shaped interfaces that were studied experimentally by Zhai et al. (2016). Experimental studies have also been conducted at the Atomic Weapons Establishment on the interaction of a shock with a finite-width interface featuring a ‘chevron’ shaped oblique perturbation by Smith et al.…”

“…Earlier experimental studies of the RMI have focused on the interaction of a planar shock with a single, sinusoidally perturbed interface (Meshkov 1969). Variations from this configuration include shock interactions with perturbed, planar interfaces such as those in the experiments of Rasmus et al (2019) and V-shaped interfaces that were studied experimentally by Zhai et al (2016). Experimental studies have also been conducted at the Atomic Weapons Establishment on the interaction of a shock with a finite-width interface featuring a 'chevron' shaped oblique perturbation by Smith et al (2001), and of half-height interfaces by Holder & Barton (2004).…”

Nonequilibrium kinetics effects in Richtmyer–Meshkov instability and reshock processes

“…The RMI has been extensively studied [28][29][30][31] in theory [32][33][34][35][36], numerical simulations [37][38][39][40][41][42][43][44][45][46][47][48][49][50], and experiments [51][52][53][54][55][56][57][58][59][60][61][62][63][64][65][66] for general conditions. The physical comprehension of RMI is becoming clearer.…”