Bulletin of the American Physical Society
72nd Annual Meeting of the APS Division of Fluid Dynamics
Volume 64, Number 13
Saturday–Tuesday, November 23–26, 2019; Seattle, Washington
Session P28: Particle Laden Flows: Shock Accelerated Flows |
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Chair: Jesse Capecelatro, University of Michigan Room: 610 |
Monday, November 25, 2019 5:16PM - 5:29PM |
P28.00001: A simple hydride model for cerium ejecta particles Jonathan D. Regele, John D. Schwarzkopf, William T. Buttler, Alan K. Harrison Cerium ejecta particles created by shock driven Richtmyer-Meshkov instabilities are known to hydride inside of deuterium gas and release exothermic energy in the form of heat and increased particle temperature. Cerium dihydride, which is the reaction product specie, is solid under the experimental conditions considered. A model is developed to describe the hydriding process by combining the lumped-capacitance thermal conduction model, Ranz-Marshall heat transfer correlation, and a diffusion-controlled reaction. Comparisons with experimental data are used to determine model accuracy and to discover what additional physics should be considered in the model. [Preview Abstract] |
Monday, November 25, 2019 5:29PM - 5:42PM |
P28.00002: Modeling pseudo-turbulence in compressible particle-laden flows Gregory Shallcross, Rodney Fox, Jesse Capecelatro When a shock passes through a dense suspension of solid particles, velocity fluctuations are generated in particle interstitial sites. While this is captured in fully resolved simulations of shock-particle interactions, it remains a challenge to reproduce using coarse-grained models, such as Eulerian-Eulerian and Eulerian-Lagrangian methods. Recent work has revealed that pseudo-turbulent kinetic energy (PTKE) can contribute significantly to the overall kinetic energy during shock-particle interactions. We demonstrate this term acts to systematically increase the local Mach number, and needs to be accounted for to properly capture particle dispersion. A transport equation for PTKE is presented, and closure for the dissipation rate is proposed. The equations are implementing in a high-order Eulerian-Lagrangian framework and compared against direct numerical simulations of shock-particle interactions. We demonstrate the model is capable of predicting the pseudo-turbulent Reynolds stresses with correct levels of anisotropy, independent of the drag law employed. Finally, a stochastic model informed by the PTKE is proposed to improve the prediction of particle dispersion. [Preview Abstract] |
Monday, November 25, 2019 5:42PM - 5:55PM |
P28.00003: Examination of Particle Force Model and its Uncertainty in a Detonation-Driven Multiphase Flow Joshua Garno, Frederick Ouellet, Rahul Koneru, Thomas Jackson, S. Balachandar, Bertrand Rollin Recent work in the compressible, multiphase flow community has shown that the compressible Maxey-Riley-Gatignol (MRG) force model captures the transient forces exerted on a particle by a passing air shock and compressed flow. In this work, the model's predictive capability in the post-detonation flow regime is considered following a rigorous study of the explosive products as the carrier phase. The model parameters of the JWL equation of state are varied to observe their individual sensitivities on the post-detonation flow. Uncertainty quantification with experimental data provides the most influential and likely JWL parameters. With the gas phase in agreement with experiments, the validity of the compressible MRG model under extreme condition is reviewed. Experimental X-ray data provides the trajectory of a few Tungsten particles ejected from an initial explosion. Particle trajectory data from experiments is compared with finite-volume, Euler-Lagrange, point-particle simulations results employing the MRG model. [Preview Abstract] |
Monday, November 25, 2019 5:55PM - 6:08PM |
P28.00004: Analyzing particle curtains with advection-corrected correlation image velocimetry and particle image velocimetry Janghan Park, Daniel Freelong, Patrick Wayne, Peter Vorobieff We conduct an experimental study of an interaction between a planar shock in air and a nominally planar curtain of particles embedded in air. We investigate shocks at Mach numbers 1.2, 1.4, 1.7, and 2.0. Particle curtains of different nominal thickness (2, 4, and 6 mm) are subjected to shock acceleration. The particles are soda lime microspheres with a density of 1.4 g/cc and diameters ranging from 30 to 50 microns. The curtain formation prior to shock arrival is recorded by a high-speed camera during 2 seconds at 960 frames per second. The curtain mass flow rate is also acquired. Each frame of the particle curtain video is analyzed with advection-corrected correlation image velocimetry (ACCIV) and particle image velocimetry (PIV). We investigate whether ACCIV offers any advantages over PIV for this flow. Measurements of velocity combined with mass flow rate data can then be used to provide an estimate of the particle volume fraction and insights into the air entrainment by the curtain. The subsequent study must relate the local volume fraction in the curtain and its thickness with the post-shock features we observe. [Preview Abstract] |
Monday, November 25, 2019 6:08PM - 6:21PM |
P28.00005: Shock interaction with particle curtains of varying thickness Daniel Freelong, Patrick Wayne, Janghan Park, Gregory Vigil, Carolina Shaheen, Peter Vorobieff The interaction of a curtain of particles with a shock wave is investigated experimentally. Soda lime particles form a gravity-driven curtain. The geometry of the curtain-forming nozzle can be adjusted, producing curtains with a nominal thickness of 2 mm, 4 mm, and 6 mm in the direction of the shock. Particle volume fractions for all three curtains range between 1{\%} and 9{\%}, with variations primarily due to particle acceleration along the vertical extent of the curtain. Prior to shock impact, we measure the instantaneous and average velocities of the particles to show that the particles are nearly in a free-falling state, with their average velocity increasing linearly with vertical distance. Experimental data reveal that the shock wave is both transmitted through and partially reflected by the curtain. Time-resolved images show the underlying flow structure of the interaction. This research is supported by the US Defense Threat Reduction Agency (DTRA) grant HDTRA1-18-1-002. [Preview Abstract] |
Monday, November 25, 2019 6:21PM - 6:34PM |
P28.00006: Mach number and particle size effects on the unsteady drag of shocked micro-droplets Kyle Hughes, Adam Martinez, John Charonko Experiments of shock-accelerated micro-droplets show high drag coefficients when the particles are tracked from initial acceleration through the relaxation times. An eight-pulse particle tracking diagnostic measures individual particle positions, and a shadowgraph system measures shock location, with pressure transducers providing shock speed at the test section. These diagnostics give us detailed measurements of particle positions versus time for Mach 1.2, 1.3 and 1.4 experiments, allowing us to calculate accelerations and drag. Comparison is made to previous experiments conducted on solid Nylon particles in similar flow regimes. [Preview Abstract] |
Monday, November 25, 2019 6:34PM - 6:47PM |
P28.00007: Evaluation of Point-Particle Models in Shock-Particle Bed Interactions Rahul Babu Koneru, Bertrand Rollin, Frederick Ouellet, S. Balachandar In this work, 3D Euler-Lagrange (EL) point-particle simulations of shock- particle cloud interaction are presented for two cases (i) shock interacting with a stationary bed of particles and (ii) a multiphase shock tube. In an effort to improve the point-particle models, results from these EL simulations are compared against particle-resolved (PR) Euler simulations in case of the stationary bed and experiments from the Multiphase Shock Tube facility at Sandia National Laboratories (SNL). In the stationary bed simulations, it is observed that at low incident shock Mach numbers and particle volume fractions (10\%-15\%), the point-particle models predict the average gas properties reasonably well. As the effects of compressibility become more prominent (presence of bow shocks), the models predict a higher drag than that is observed in the PR simulations. A sensitivity analysis is performed to identify the force components responsible for this additional drag. In the case of the multiphase shock tube, the effects of particle collisions and the initial curtain profile on the curtain expansion rate are explored. The particle collisions in this case are modeled using a soft-sphere type DEM model in CMT-Nek. [Preview Abstract] |
Monday, November 25, 2019 6:47PM - 7:00PM |
P28.00008: Implementation of Key Capabilities to Study Unsteady Drag of Shock-Accelerated Particles with an Arbitrary Lagrangian-Eulerian Code Tanner Nielsen, W. Curtis Maxon, Nick Denissen The dynamic drag coefficient on particles due to shock-acceleration has been observed, experimentally and computationally, to significantly increase during the passage of the shock over the particle. The later times, after the passage of the shock during which the particle is accelerated to the post-shock conditions, have not been as thoroughly studied nor are there models that accurately capture drag effects in this unsteady regime. This work details key capabilities that have recently been added to FLAG, an arbitrary Lagrangian-Eulerian (ALE) code developed at Los Alamos National Laboratory, to enable to the study of shock-accelerated particles. This unique simulation tool allows high-resolution studies of a single particle from rest to post-shock acceleration. The ALE framework permits the particle to move freely within the computational domain based on the pressure and viscous forces. Details will be given regarding the implementation of the viscous terms in FLAG to enable the solution of the Navier-Stokes equations for the air surrounding the particle. The drag calculation is done in a way that allows the integration of the forces on the particle as it moves freely through the domain. [Preview Abstract] |
Monday, November 25, 2019 7:00PM - 7:13PM |
P28.00009: High Resolution Simulations of Particle Acceleration in Shock-Driven Multiphase Flows William Maxon, Tanner Nielsen, Nicholas Denissen, Jonathan Regele, Jacob McFarland Particle drag models, which capture macro viscous and pressure effects, have been developed over the years for various flow regimes to enable cost effective simulations of particle-laden flows. The relatively recent derivation by Maxey and Riley has provided an exact equation of motion for spherical particles in a flow field based on the continuum assumption. Many models that have been simplified from these equations have provided reasonable approximations; however, the sensitivity of the shock-driven multiphase instability to particle drag requires a very accurate model to simulate. To develop such a model, 2D axisymmetric and 3D Cartesian Navier-Stokes DNS of a single particle in a transient, shock-driven flow field were conducted in the hydrocode FLAG. FLAG's capability to run arbitrary Lagrangian-Eulerian (ALE) hydrodynamics coupled with solid mechanic models in solids makes it an ideal code to capture the physics of the flow field around the particle as it is shock-accelerated -- a challenging regime to study. Preliminary results have shown higher drag than the current models predict. Simulation results will be used to create a new drag model for multiphase particle-in-cell methods. [Preview Abstract] |
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