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 B05: Compressible Flows: Shock Waves and Explosions |
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Chair: Michael Hargarther, New Mexico Tech Room: 204 |
Saturday, November 23, 2019 4:40PM - 4:53PM |
B05.00001: Scale-invariant Homentropic Compressible Flows and Their Application to the Noh Problem Jesse Giron, Scott Ramsey, Roy Baty The purpose of this work is to examine the group invariance properties of the inviscid Euler equations, subject to an equation of state (EOS) where the fluid pressure is regarded solely as an arbitrary function of the fluid density. We derive the conditions under which the resulting \emph{homentropic} Euler equations and associated shock jump conditions are invariant under scaling groups. The invariance properties of these relations are used to construct a Noh-like solution featuring a constant velocity stagnation shock. For this solution to exist, we demonstrate that the EOS must satisfy a transcendental algebraic relation. [Preview Abstract] |
Saturday, November 23, 2019 4:53PM - 5:06PM |
B05.00002: Quasi-Similar Converging Shock Flows for a Mie-Gruneisen Equation of State Emma Schmidt, Scott Ramsey, Roy Baty The Guderley hydrodynamic test problem is an example of a self-similar, scale-invariant solution of the inviscid Euler equations. It consists of an infinitely strong shock wave converging to an axis or point of symmetry, where the defined flow has the notable property of being independent of a system of units. A key piece of the self-similar analysis is selecting a material that exhibits scale invariant behavior. The symmetry properties of the Euler equations have been used by several authors to determine the general form of an equation of state (EOS) that permits the existence of scale-invariant solutions. However many widely used EOSs, such as the Mie-Gruneisen EOS for crystalline solids, are not of the required form. We propose a joint similarity-perturbative analysis that modifies the classical self-similar solutions of the Euler equations to represent non-ideal material behavior, and perform the quasi-similar analysis of the Guderley problem in a non-ideal material defined by the Mie-Gruneisen EOS. LA-UR-19-27159. [Preview Abstract] |
Saturday, November 23, 2019 5:06PM - 5:19PM |
B05.00003: Numerical modeling of solid-cluster evolution applied to the nanosecond solidification of water through ramp and shockwave compression Dane Sterbentz, Philip Myint, Jean-Pierre Delplanque, Jonathan Belof Classical nucleation theory (CNT) is a promising way to predictively model the sub-microsecond kinetics of rapid phase transitions that occur under ramp or shock compression, such as the suite of experiments performed over the past two decades on the solidification of liquid water to the high-pressure ice VII phase. We model the liquid water--ice VII phase transformation in these hydrodynamic-loading experiments using a numerical discretization scheme to solve the Zel'dovich--Frenkel partial differential equation (a fundamental CNT-based kinetic equation that describes the statistical time-dependent behavior of solid cluster formation and accounts for transience in the nucleation kinetics) as well as through hydrodynamics simulations. We have also developed a new dimensionless parameter that may be applied \textit{a priori} to predict whether or not transient nucleation will be important in a given ramp- or shock-compression experiment. [Preview Abstract] |
Saturday, November 23, 2019 5:19PM - 5:32PM |
B05.00004: Shock-wave structure according to the Navier--Stokes--Fourier constitutive relations Francisco J. Uribe, Rosa M. Velasco The Navier--Stokes--Fourier constitutive equations are used to study plane shock--waves in dilute gases. We use the soft sphere model in which the viscosity and thermal conductivity are proportional to a power of the local temperature: $\eta, \kappa \sim T^\sigma$, $\sigma$ being the viscosity index . We show that the experimental normalized density profiles for argon can be fit with the viscosity index. Results form the direct simulation Monte Carlo method and with transport coefficients obtained from ab initio potentials are also considered. [Preview Abstract] |
Saturday, November 23, 2019 5:32PM - 5:45PM |
B05.00005: Non-classical behavior in shock-compressed gas mixtures Patrick Wayne, Peter Vorobieff, Carolina Shaheen, Daniel Freelong, C. Randall Truman Rankine-Hugoniot (R-H) equations, while assuming a calorically perfect gas, provide a good approximation for real gases undergoing shock compression. Our experiments focus on problems that arise when an attempt to predict post-shock gas properties is made for a non-reacting mixture of two gases with highly disparate properties (hydrogen and sulfur hexafluoride). Although the range of Mach numbers we consider is quite modest(1.2 to 2.0), we observe major deviations from the behavior that classical models predict. The latter include R-H equations in combination with either Dalton's or Amagat's law to characterize the gas mixture. Moreover, we observe these deviations to persist on time scales much longer than those historically associated with non-equilibrium behavior due to shock front passage. [Preview Abstract] |
Saturday, November 23, 2019 5:45PM - 5:58PM |
B05.00006: Multi-dimensional evolution of explosive product gas cloud Part I: Evolution in confined two-dimensional and three-dimensional geometries Veronica Espinoza, Christian Peterson, Michael Hargather The evolution of an explosively-driven gas cloud was studied at different scales, geometries, and confinements. The tests used exploding bridgewires and small PETN charges as the explosion sources and measured the shock wave and gas production. These experiments were imaged with high-speed schlieren imaging to visualize the produced gas cloud and the evolution of the surface motion. The explosive events were confined between two acrylic sheets with a varied confinement thickness. Image processing is used to track the gas cloud and to characterize the complexity of the surface in terms of a fractal dimension. Turbulence quantities are estimated from the refractive images and show variations as a function of confinement thickness. [Preview Abstract] |
Saturday, November 23, 2019 5:58PM - 6:11PM |
B05.00007: Multi-dimensional evolution of explosive product gas cloud Part II: Three-dimensional gram-scale charges Christian Peterson, Veronica Espinoza, Kyle Winter, Michael Hargather The evolution of an explosively-driven gas cloud was studied using gram-scale explosive charges. Spherical explosive charges were suspended in free-air above a solid surface and detonated, producing a shock wave and expanding gas cloud. The explosions were imaged with shadowgraphy and background oriented schlieren from multiple views. The individual views are used to track the evolution of the gas cloud surface in two dimensions. The views are combined to produce a three-dimensional reconstruction of the gas cloud. The fractal dimension of the gas cloud surface is measured from the digital images as a measure of the complexity of the surface. The time-evolution of the turbulence and surface details are measured. Results are compared to smaller-scale open air tests. [Preview Abstract] |
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