Vortex Formation in a Shock-Accelerated Gas Induced by Particle Seeding

Vorobieff, Peter; Anderson, Michael J.; Conroy, Joseph; White, Ross; Truman, C. Randall; Kumar, Sanjay

doi:10.1103/physrevlett.106.184503

Cited by 56 publications

(34 citation statements)

References 19 publications

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“…Our recent experiments [17,18] confirm formation of large-scale vortices in a gaseous medium non-uniformly seeded with micron-or submicron-sized droplets or particles after shock acceleration. The flow structure superficially resembles one that would emerge after shock acceleration of continuous medium with average initial density matching that of our two-phase, non-uniformly seeded medium.…”

Section: Introductionsupporting

confidence: 59%

Analogues of Rayleigh-Taylor and Richtmyer-Meshkov instabilities in flows with nonuniform particle and droplet seeding

Vorobieff

Anderson

Conroy

et al. 2011

Computational Methods in Multiphase Flow VI

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The well-known Rayleigh-Taylor (RT) and Richtmyer-Meshkov (RM) instabilities characterize the behavior of flows where two gases (or fluids) of different densities mix due to gravity (RT) or due to impulsive acceleration (RM). Recently, analogous instabilities have been observed in two-phase flows where the seeding density of the second phase, e.g., particles or droplets in gas, and the resulting average density, is initially non-uniform. The forcing causes the second phase to move with respect to the embedding medium. With sufficient seeding concentration, this leads to entrainment of the embedding phase. The resulting movement is similar to the movement that would evolve in a mixing flow with no second phase seeding, but with non-uniform density (not unlike a mixture of lighter and heavier gases), where RT and RM instabilities develop in the case of gravityinduced and impulsive acceleration, respectively. The hydrocode SHAMRC has been used in the past to study the formation and growth of the RM instability. Here we attempt to use it to model the first order formation and growth phenomena of the new class of instability in two-phase flows first, by approximating the second phase as a continuous fluid with an averaged density, and second, by taking the relative motion of particles (droplets) into account explicitly. The initial conditions are varied to provide a wide range of instability growth rates. Comparison of the numerical results with experiment shows good agreement.

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Section: Introductionsupporting

confidence: 59%

Analogues of Rayleigh-Taylor and Richtmyer-Meshkov instabilities in flows with nonuniform particle and droplet seeding

Vorobieff

Anderson

Conroy

et al. 2011

Computational Methods in Multiphase Flow VI

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show abstract

“…This α value agrees with "classical" RTI experiments [14]. Experiments with an analog of RMI on an interface between unseeded air and air seeded with glycol droplets also led to vortex formation not unlike that characteristic of RMI, but with important differences in the physical mechanisms responsible for the vorticity deposition [15,16].…”

Section: Introductionsupporting

confidence: 81%

“…The evolution of the flow after shock acceleration is described elsewhere [15,16]. Here we focus on the reshock occurring after a M = 1.2 shock is reflected from an aluminum flange placed between the test section and the runoff section.…”

Section: Results Of Experimentsmentioning

confidence: 99%

Vortex deposition in shock-accelerated gas with particle/droplet seeding

Vorobieff¹,

Anderson²,

Conroy³

et al. 2012

AIP Conference Proceedings

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Abstract. We present an experimental and numerical study of post-shock evolution of gas initially seeded with small droplets or particles. In two-phase media with gas being the embedding phase occupying most of the volume, shock acceleration can lead to vortex formation. The physical mechanism responsible for the vorticity deposition in this case is different from that of Richtmyer-Meshkov instability that would emerge on a gas-gas density interface. After the shock passage, the particles or droplets lag behind the surrounding gas. Momentum exchange between the embedded phase and the embedding phase leads to non-uniform local equilibrium velocity distribution, and thus to shear and vortex formation. Here we investigate shock interaction with a cylindrical particle-seeded column (with and without reshock).

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“…The late-time results were roughly consistent with K41 prediction of 2/3 power-law scaling for the second-order longitudinal velocity structure function. Sadly, at higher Mach numbers, tracer particles used for PIV present an increasing problem because they don't follow the gas flow [21] and interfere with flow physics [18]. Here we use a cleaner diagnostic (PLIF), however, it does not easily yield results in terms of velocity, because it effectively shows cross- diffusive passive scalar and even of a reacting component in the flow [22], and moreover, has an equivalent representation in terms of the second-order structure function of the scalar (under the same conditions that ensure the equivalence of the -5/3 and 2/3 laws for velocity spectra and structure functions [22]).…”

mentioning

confidence: 99%

Shock-driven transition to turbulence: Emergence of power-law scaling

et al. 2017

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We consider two cases of interaction between a planar shock and a cylindrical density interface.In the first case (planar normal shock), the axis of the gas cylinder is parallel to the shock front, and baroclinic vorticity deposited by the shock is predominantly two-dimensional (directed along the axis of the cylinder). In the second case, the cylinder is tilted, resulting in an oblique shock interaction, and a fully three-dimensional shock-induced vorticity field. The statistical properties of the flow for both cases are analyzed based on images from two orthogonal visualization planes, using structure functions of the intensity maps of fluorescent tracer pre-mixed with the heavy gas.At later times, these structure functions exhibit power-law-like behavior over a considerable range of scales. Manifestation of this behavior is remarkably consistent in terms of dimensionless time τ defined based on Richtmyer's linear theory within the range of Mach numbers from 1.1 to 2.0 and the range of gas cylinder tilt angles with respect to the plane of the shock front (0 to 30 • ).

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Vortex Formation in a Shock-Accelerated Gas Induced by Particle Seeding

Cited by 56 publications

References 19 publications

Analogues of Rayleigh-Taylor and Richtmyer-Meshkov instabilities in flows with nonuniform particle and droplet seeding

Analogues of Rayleigh-Taylor and Richtmyer-Meshkov instabilities in flows with nonuniform particle and droplet seeding

Vortex deposition in shock-accelerated gas with particle/droplet seeding

Shock-driven transition to turbulence: Emergence of power-law scaling

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