Bulletin of the American Physical Society
2005 58th Annual Meeting of the Division of Fluid Dynamics
Sunday–Tuesday, November 20–22, 2005; Chicago, IL
Session HM: Compressible Flows |
Hide Abstracts |
Chair: Joanna Austin, University of Illinois, Urbana-Champaign Room: Hilton Chicago PDR 1 |
Monday, November 21, 2005 1:20PM - 1:33PM |
HM.00001: Reflection and focus of shock waves in lithotripsy Jonathan Iloreta, Andrew Szeri, Georgii Sankin, Yufeng Zhou, Pei Zhong Controlling cavitation has been a primary focus in shock wave lithotripsy (SWL), and techniques such as pulse superposition and waveform inversion have been used to suppress and/or enhance bubble collapses. In order to assess the effectiveness of these ideas, a numerical model of the reflection and steepening of a pressure wave from an axisymmetric lithotripter has been made. The model is based on the Euler equations coupled with the Tait equation of state. It captures wave dynamics in the solid through changes in the reflection coefficient. Results of the pressure field for different reflector shapes are compared with experimental measurements from laser and spark induced shock waves. The designs are evaluated based on how they affect bubbles in the flow field. [Preview Abstract] |
Monday, November 21, 2005 1:33PM - 1:46PM |
HM.00002: Subsonic Compressible Flow in Two-Sided Lid-Driven Cavity Palak Shah, Farzad Mashayek, Gustaaf Jacobs This paper presents a numerical study of the laminar, viscous, subsonic compressible flow in a two-dimensional two-sided lid- driven cavity using a multi-domain spectral element method. The flow is driven by steadily moving two opposite walls vertically in opposite directions. The results of the simulations are used to investigate the effects of the cavity aspect ratio, the Reynolds number and the Mach number on the flow. Cases with equal wall temperatures and with unequal wall temperatures are considered. The flow evolution shows that the basic two- dimensional flow obtained is not distinctive. This is particularly true when the temperatures of the two walls are not equal. The increase of this temperature difference changes the steady state flow from a single-vortex to a two-vortex pattern. For cases with equal wall temperatures, at lower Reynolds numbers, the flow pattern consists of two separate co- rotating vortices contiguous to the moving walls. For higher Reynolds numbers, initially a two-vortex flow is formed, which eventually turns into a single elliptical vortex occupying most of the cavity. For a higher aspect ratio, the flow patterns are dissimilar in that the streamlines become more and more elliptic. For aspect ratios as high as 2.5, at high Reynolds numbers, a three-vortex stage is formed. Energy balance studies are conducted at steady state and during flow evolution. The evolution and distribution of heat transfer and work at walls are studied. [Preview Abstract] |
Monday, November 21, 2005 1:46PM - 1:59PM |
HM.00003: Pressure-driven wave propagation in mm-scale channels Joanna Austin Miniaturized analysis systems, which may potentially revolutionize detection of air-borne biological or chemical agents through increased portability and real time response, also present exciting fundamental challenges. Development of integrated total analysis systems will depend on optimizing the interaction of multiple components such as valves, injectors, pumps, and channels. In pressure-driven systems, such components may produce finite amplitude waves and wave attenuation may then be a key design factor in optimizing both devices that operate on steady-state assumptions and devices where unsteadiness is cultivated, for example mixers. A fundamental experimental investigation of wave propagation as a function of the channel size was performed. A shock wave is transmitted into mm-scale channels to achieve a well-characterized initial condition. Wave attenuation and structure information is obtained from time-of-arrival data and pressure histories along the channel. Experimental results are compared with models developed for the analogous flow regime of wave propagation through macroscale channels in low pressure environments. [Preview Abstract] |
Monday, November 21, 2005 1:59PM - 2:12PM |
HM.00004: Experimental Validation of Detonation Shock Dynamics in Condensed Explosives D. Scott Stewart, David E. Lambert, Sunhee Yoo, Bradley Wescott Experiments on the HMX-based, condensed explosive PBX-9501 were carried out to validate a reduced asymptotically derived description of detonation shock dynamics (DSD) where it is assumed that the normal detonation shock speed is determined by the total shock curvature. The passover experiment has an embedded lead disk in a right circular cylindrical charge of PBX-9501 and is initiated from the bottom. A range of dynamically changing states, with both divergent (convex) and converging (concave) shock shapes are realized as the detonation passes over the disk. The time of arrival of the detonation shock at the top surface of the charge is recorded and compared against the DSD simulation and a separate multi-material simulation (DNS). A new wide- ranging equation of state (EOS) and rate law is used to describe the explosive and is employed in both the theoretical (DSD) calculations and the multi-material simulations. The experiment, theory and simulation are found to be in excellent agreement. [Preview Abstract] |
Monday, November 21, 2005 2:12PM - 2:25PM |
HM.00005: Numerical Study of Detonation Expansion from a Small Channel to a Large One Miltiadis Papalexandris, Christian Jacobs, Jean-Francois Thomas, Vincent Deledicque This presentation reports on numerical results for the evolution of a detonation wave that is expanded from a small channel to a larger one. In accordance with experimental data, the simulations predict three different types of evolution, supercritical, critical and subcritical ones. In a supercritical detonation, the reaction zone remains always attached to the precursor shock. A critical detonation is characterized by temporary extinction and reinitiation at later times. In a subcritical detonation, the extinction is permanent, i.e., there is a permanent decoupling of the reaction zone from the leading front. The presentation concludes with a parametric study on the effects of the activation energy of the fuel and the channel-width ratio. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700