Bulletin of the American Physical Society
66th Annual Meeting of the APS Division of Fluid Dynamics
Volume 58, Number 18
Sunday–Tuesday, November 24–26, 2013; Pittsburgh, Pennsylvania
Session A30: Instability: Richtmyer-Meshkov |
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Chair: Davesh Ranjan, Texas A&M University Room: 408 |
Sunday, November 24, 2013 8:00AM - 8:13AM |
A30.00001: Large Eddy Simulation Requirements for the Richtmyer-Meshkov Instability Britton Olson, Jeff Greenough The shock induced mixing of two gases separated by a perturbed interface is investigated through Large Eddy Simulation and Direct Numerical Simulation. At coarse resolutions, the effects of numerical dissipation outweigh those of physical dissipation on the entrainment and mixing process of the Richtmyer-Meshkov Instability. Decreasing the Reynolds of the flow while increasing the grid resolution largely mitigates the relative numerical dissipation but is often unachievable for realistic flows. A model for an effective viscosity is proposed which allows for an \textit{a posteriori} analysis of the simulation data that is agnostic to the LES model, numerics and the physical Reynolds number of the simulation. An analogous approximation for an effective species diffusivity is also presented. This framework can then be used to estimate the effective Reynolds number and Schmidt number of future simulations and elucidate the impact of numerical dissipation on the mixing process for an arbitrary numerical method. [Preview Abstract] |
Sunday, November 24, 2013 8:13AM - 8:26AM |
A30.00002: Experimental Parametric Study of the Inclined Interface Richtmyer-Meshkov Instability Jacob McFarland, Skylar Creel, David Reilly, Christopher McDonald, Jeffrey Greenough, Devesh Ranjan Experiments performed in the Texas A\&M shock tube facility will be presented which explore the effect of incident shock strength, Atwood number, and inclination angle on the development of the Richtmyer-Meshkov instability. Experiments with a range of Atwood numbers ($\sim$0.23 to 0.85) and high interface inclination angles ($>$45$^\circ$) at moderate incident shock Mach numbers ($\sim$1.55 and 1.9) will be presented. Qualitative results will be presented using Mie scattering images obtained from early to late times before reshock. Quantitative results such as the interface mixing width growth rate, and vorticity deposition will be presented for select cases. Experimental results will also be compared with simulation results from the Lawrence Livermore National Laboratory's ALE hydrodynamics code, ARES. [Preview Abstract] |
Sunday, November 24, 2013 8:26AM - 8:39AM |
A30.00003: Experimental Study of the Richtmyer-Meshkov Instability on a Coupled Multimode and Inclined Interface Perturbation David Reilly, Skylar Creel, Jacob McFarland, Jatin Mitruka, Christopher McDonald, Devesh Ranjan The inclined shock tube in the Texas A\&M Shock Tube and Advanced Mixing Laboratory was used to study the effect of small amplitude, long wavelength multimode perturbations imposed on the inclined interface initial condition of the Richtmyer-Meshkov instability. The inclined interface is essentially a long wavelength, extremely large amplitude perturbation. Images of the shocked flow-field were captured with the angle of the shock tube with respect to the horizontal at 60$^\circ$ ($\eta$/$\lambda$ = $\sqrt3$/6). The modal content of the initial conditions was determined by taking the Fourier decomposition of the interface. This work is a proof of concept for creating a coupled multimode and inclined interface. Work that is currently underway will investigate the effect of these initial conditions on intermediate and late-time mixing as well as the transition to turbulence before reshock by using qualitative comparisons of Mie scattering images, mixing width measurements, and circulation from Particle Image Velocimetry (PIV). [Preview Abstract] |
Sunday, November 24, 2013 8:39AM - 8:52AM |
A30.00004: Inclined Interface Richtmyer-Meshkov Instability: Reshock Study Skylar Creel, Jacob McFarland, David Reilly, Chris McDonald, Shanae Smith, Devesh Ranjan Experimental work performed in the Texas A\&M University Shock Tube and Advanced Mixing Lab will be presented focusing on the effort to drive the Richtmyer-Meshkov instability to a turbulent state through the use of reshock. Experiments presented will feature a range of Atwood numbers ($\sim$0.23 to 0.67) at an inclination angle of 60$^\circ$, Mach numbers of $\sim$1.55 and $\sim$1.91 and mulitiple reshock interaction times. Experiments will qualitatively detail the effect of reshock interaction time on the developing instability through Mie scattering images. Velocity fields will be acquired through the use of particle image velocimetry (PIV). Quantitative measurements of vorticity, using velocity fields, and mixing width growth rates, using Mie scattering images, of the reshocked flow will be compared to their pre-reshock values. Comparison will provide information on the effect of reshock on the level of turbulence in the flow. [Preview Abstract] |
Sunday, November 24, 2013 8:52AM - 9:05AM |
A30.00005: ABSTRACT WITHDRAWN |
Sunday, November 24, 2013 9:05AM - 9:18AM |
A30.00006: Three-dimensional features of shock-driven mixing flow Dell Olmstead, Peter Vorobieff, Clint Corbin, Tennille Bernard, Patrick Wayne, Garrett Kuehner, C. Randall Truman Richtmyer-Meshkov instability (RMI) is created by passing an oblique shock wave across a cylindrical column of heavy gas (sulfur hexafluoride SF$_6$) in air at Mach numbers ranging from 1.2 to 2.0. These initial conditions are inherently three-dimensional, unlike nominally two-dimensional conditions used in many earlier works. To capture the development of the RMI, Planar Laser Induced Fluorescence (PLIF) images were obtained in multiple planes along and across the RMI-perturbed column. The oblique shockwave is obtained in a shock tube inclined up to 30 degrees with the horizontal and using gravity-driven (vertical) flow to form the SF6 cylinder. The development of RMI for a cylindrical interface subjected to a normal shockwave is also documented. The main subject of the investigation is the role of the angle between the cylinder and the shock front in the formation and evolution of the three-dimensional features in the flow. Experiments also show that consideration must be given to the effects of the walls of the shock tube and especially of the holes in the walls used to form the heavy-gas column. [Preview Abstract] |
Sunday, November 24, 2013 9:18AM - 9:31AM |
A30.00007: Dependence of Single-Interface Richtmyer-Meshkov Mixing on Mach Number using Simultaneous PIV and PLIF Measurements Brandon M. Wilson, Ricardo Mejia-Alvarez, Kathy P. Prestridge Richtmyer-Meshkov mixing is dependent upon initial interface perturbations, incident shock Mach number, Atwood number, and other fluid properties. The correlation between turbulence quantities and mixing parameters with these properties is not well-understood. The Vertical Shock Tube (VST) at Los Alamos National Lab is designed to measure turbulence and mixing from the Taylor micro-scale to the largest scales (mix width). We use simultaneous velocity (PIV) and density (PLIF) diagnostics to understand the effects of incident Mach number on statistically-invariant, multimode perturbations of an air-SF6 interface (Atwood number corrected for acetone diagnostic is $A=$0.57). We quantify Ma effects on mixing at both large and small scales by measuring the time evolution of various mixing parameters ($e.g.$ mixing width, Favre-averaged Reynolds stresses, and vorticity), and we compare these results to previous studies. Late mixing after the first shock resembles a turbulent flow, and we examine the nature of the turbulence and condition of turbulent transition. [Preview Abstract] |
Sunday, November 24, 2013 9:31AM - 9:44AM |
A30.00008: Simultaneous PIV/PLIF measurements of Richtmyer-Meshkov Instabilities from single- and multi-mode perturbed interfaces Ricardo Mejia-Alvarez, Brandon Wilson, Kathy Prestridge To support validation of RANS and LES codes for single-interface Richtmyer-Meshkov mixing, the Extreme Fluids Team at Los Alamos National Laboratory commissioned a Vertical Shock Tube. This facility has the capability of generating statistically stationary single- and multi-mode spatial perturbations on the fluid interface prior to shock-interface interaction. The present study focuses on comparing the evolution of shock-driven mixing under two different spatial perturbation conditions after interacting with a M=1.2 shock wave. High resolution simultaneous PIV and PLIF are used for capturing 2D instantaneous realizations of velocity and density at different stages of the evolving interface. Multiple realizations of the flow at each one of these evolution stages are obtained to characterize the flow statistically. Also, a modal analysis via Singular Value Decomposition is performed on the density and velocity fields to elucidate the role of initial flow scales content on the transition to turbulent mixing. [Preview Abstract] |
Sunday, November 24, 2013 9:44AM - 9:57AM |
A30.00009: Simultaneous Concentration and Velocity Field Measurements in a Shock-accelerated Mixing Layer Daniel Reese, Jason Oakley, Chris Weber, David Rothamer, Jose Navarro, Riccardo Bonazza The Richtmyer-Meshkov instability (RMI) is experimentally investigated at the Wisconsin Shock Tube Laboratory. Simultaneous concentration and velocity field measurements from the mixing layer of experimental RMI images are obtained through the application of the Advection-Corrected Correlation Image Velocimetry (ACCIV) technique. A statistically repeatable broadband initial condition is created by first setting up a gravitationally stable stagnation plane of helium$+$acetone over argon and then injecting the gases horizontally at the interface to create a shear layer. The shear layer is then accelerated by a Mach 2.2 planar shock wave that causes the growth of any perturbations present at the interface, and time-separated image pair data of the mixing layer are obtained using planar laser induced fluorescence (PLIF). The image pair is corrected to show relative acetone concentration, and is then used as input to the ACCIV algorithm to obtain velocity field results. These velocity field measurements are compared with those obtained from numerical simulations. Turbulent kinetic energy spectra are compared with particle imaging velocimetry (PIV) and simulation results to validate regions of applicability. [Preview Abstract] |
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