Bulletin of the American Physical Society
75th Annual Meeting of the Division of Fluid Dynamics
Volume 67, Number 19
Sunday–Tuesday, November 20–22, 2022; Indiana Convention Center, Indianapolis, Indiana.
Session J10: Compressible Flows: General |
Hide Abstracts |
Chair: Roy Baty, Los Alamos Natl Lab Room: 137 |
Sunday, November 20, 2022 4:35PM - 4:48PM |
J10.00001: On the Integrability of Subsonic Compressible Potential Flow Around Cylinders Roy S Baty, Scott D Ramsey This work analyzes the local integrability of the potential equation for steady, compressible flow in the plane. The classical problem of flow past a circular cylinder is analyzed for free-stream Mach numbers that yield subsonic flow fields. Theorems from differential geometry are applied to study the local integrability of the governing potential equation. The linearized potential equation is analyzed using both the vector field form and the dual formulation in terms of differential ideals. Differential ideals are applied in the analysis by casting the compressible potential equation as an exterior differential system with an independence condition. The resulting exterior differential system is a Pfaffian system which converts the difficult analysis question of local solvability about non-singular points to a simpler problem in linear algebra. A global version of the integrability result is also applied which gives the geometric conditions required for the solution of the potential equation for the subsonic flow around a circular cylinder to decompose into a foliation. The relationship of the leaves of the foliation to the streamlines around the cylinder is considered. |
Sunday, November 20, 2022 4:48PM - 5:01PM |
J10.00002: On the Integrability of Subsonic Compressible Potential Flow Around Bodies of Revolution Scott D Ramsey, Roy S Baty This work applies differential geometry concepts involving integrability to the linearized potential equation for steady, compressible flow around axisymmetric bodies in space. The classical problem of flow past a sphere is analyzed for free-stream Mach numbers that yield subsonic flow fields. For this scenario, after casting the relevant linearized potential equation as an exterior differential system, the isovector method may be used to construct infinitesimal vector fields or Lie group generators encoding the invariance properties of the coordinate-free representation. This vector field then has a number of important applications to the underlying mathematical model, including categorization of its underlying Lie symmetries, association of those symmetries with readily observable flow behaviors, interrogation of conditions for local integrability, and identification and characterization of obstructions in extending from local to global integrability. This analysis is intended to provide a direct connection between these abstract geometric concepts and a classical, thoroughly understood physical model. |
Sunday, November 20, 2022 5:01PM - 5:14PM |
J10.00003: Application of the Janzen-Rayleigh Method to Obstructed Flow Tyler Remedes, Scott D Ramsey, Roy S Baty The Janzen-Rayleigh method is a familiar solution technique used to describe the flow of an inviscid, compressible fluid around a cylinder through an expansion in the Mach number. The purpose of this work is to use this familiar methodology to elucidate the concepts described by Baty and Ramsey. Previous work describes the process of using differential geometries to describe the flow around a spherical object and identify salient physics occurring in the problem. This work validates the aforementioned solutions using a well-known technique, and therefore, validates the physical conclusions previously presented. Further, this work extends the number of known solutions found when applying the Janzen-Rayleigh method to this type of problem. LA-UR-22-27339 |
Sunday, November 20, 2022 5:14PM - 5:27PM |
J10.00004: Flow unsteadiness in the near-wake of a supersonic cylinder Ravi Sankar Vaddi, Premika S Thasu, Subhajit Das, Subrahmanyam Duvvuri High speed flow over a 2D circular cylinder produces coherent flow oscillations in the near-wake region. Previous experimental studies at free-stream Mach numbers M∞ = 4 and 6 have identified the length of the near-wake free shear layers (S) as the relevant length scale for the oscillations. The oscillation Strouhal number, formed using S and the free-stream velocity, was found to exhibit universal behavior with respect to the Reynolds number, and the universality was also seen to hold for both M∞ = 4 and 6. The present work aims to investigate if the universal behavior extends down to a lower supersonic Mach number. Experiments are being carried out in the Satish Dhawan Supersonic Wind Tunnel at IISc at M∞ = 2.3, at various Reynolds numbers. The frequency of oscillations and other flow features of interest are extracted by spectral proper orthogonal decomposition (SPOD) of high-speed schlieren data. The complete experimental results along with a discussion will be presented at the meeting. |
Sunday, November 20, 2022 5:27PM - 5:40PM |
J10.00005: Large-eddy simulation of a Mach 6 cylinder wake Gaurav Kumar, Subrahmanyam Duvvuri The unsteady wake of a circular cylinder at Mach 6 and Reynolds number 5 x 105 (based on free-stream flow conditions and cylinder diameter) is investigated with large-eddy simulation (LES) of the flow. The high-speed cylinder wake has remarkably distinct appearance and dynamics from its low-speed counterpart. Supersonic flow separation on the aft side is accompanied by separation and reattachment shock waves along with formation of symmetric (top/bottom) shear layers. These shear layers intersect at a downstream location at the centerline. Recent experiments of this flow have revealed coherent flow oscillations in the wake, centered around the region of shear layers intersection, with the Strouhal number exhibiting universal behavior. The present effort aims to understand the mechanism sustaining the unsteadiness through the simulation results. Basic flow features from the simulation are found to be in agreement with experimental observations, and a detailed analysis of the results is presently underway. The complete set of computational results along with a discussion will be presented at the meeting. |
Sunday, November 20, 2022 5:40PM - 5:53PM |
J10.00006: Investigation of Mach number effects on flow over a rectangular cylinder around critical geometry at Reynolds number O(103) using a low-density wind tunnel Satoshi Kimura, Takayuki Nagata, Miku Kasai, Yuta Ozawa, Taku Nonomura In this study, drag force measurements were conducted for subsonic compressible flows around a rectangular cylinder with a side length ratio from 0.5 to 1.2 near the critical geometry, a side length ratio of which was reported to be 0.65 for incompressible flow in the previous study. The effect of the compressibility on the critical geometry was evaluated using a low-density wind tunnel in the Mach number range from 0.1 to 0.6 at the Reynolds number of O(103). The side length ratio with the peak drag coefficient was confirmed to change with the Mach numbers. Remarkably, the peak drag coefficient for the side length ratio of 1.0 was observed at the Mach number of 0.6. In addition, the change in the flow field was investigated using the time-resolved schlieren visualization, and the flow field was discussed with the force measurement results. The change in the flow fields behind cylinders that have different side length ratios is related to the back pressure, and it results in a significant change in the drag coefficient. |
Sunday, November 20, 2022 5:53PM - 6:06PM |
J10.00007: TRANSIENT PHENOMENA ASSOCIATED WITH MODE TRANSITION IN STRUT-BASED DUAL-MODE SCRAMJET ENGINES Rajesh Kumar, AMARDIP GHOSH A strut-based, parallel-flow, supersonic combustor, based on the DLR geometry, was numerically simulated for mode transition, both from supersonic to subsonic and from subsonic to supersonic modes by throttling the fuel flow rate while holding the air flow rate constant. Both RANS and URANS simulations were performed using ANSYS-Fluent software to capture steady behaviour at fixed fuel-flow rate and unsteady behaviour for step changes in fuel-flow rate respectively. |
Sunday, November 20, 2022 6:06PM - 6:19PM |
J10.00008: Leading-edge separation in hypersonic flow Karthick SK, Soumya R Nanda, Jacob Cohen Leading-edge separation and the resulting unsteadiness are a byproduct of flow turning around a blunt body with a sharp axial protrusion at hypersonic speed. The resulting flow dynamics impose severe fluid-structure interaction and substantial heat transfer on the immersed body. A hypersonic Ludweig tunnel is built to produce an impulse flow at M∞=6. An axisymmetric flat-face cylinder of diameter D=35 mm is equipped with a sharp-tip spike of different lengths and spike diameters to induce the leading-edge separation. Unsteady pressure measurements on the base body along with high-speed images from the schlieren and the laser-based Rayleigh scattering resolve the flow field spatiotemporally. Two different forms of unsteadiness involving pulsation and flapping are observed. Flapping unsteadiness is observed for a wide range of Reynolds numbers (ReD) and geometrical configurations. The signature of the shock oscillation during flapping depends on the nature of the separated shear layer undergoing a transition from laminar to a turbulent state. Analysis of shock-foot oscillations using x-t diagrams from the high-speed schlieren images for the longest spike reveals a change in spectra from discrete to broadband while varying from low to high ReD. Similarly, unsteady pressure measurements show a four-order reduction in the power spectra while increasing the spike length by two times. More details on the experiments and discussions will be presented at the conference. |
Sunday, November 20, 2022 6:19PM - 6:32PM |
J10.00009: Alternative Analytical Solution for Planar Oblique Shock Waves Steven A Miller One now famous analytical solution for shock waves was developed by Dr. Theodore Meyer within his Ph.D. dissertation under advisement of Professor Ludwig Prandtl. The original solution relies on analysis via control volume of the equations of motion. This approach has limited future development of analytical solutions for more complex flow-fields. In this presentation, we recover the classic solution of Meyer for the planar oblique shock wave via a new approach. We recast the Navier-Stokes equations in terms of generalized functions and an arbitrary surface that evolves in space and time. A closed-form solution for the density field is found, which depends on the integration of a Green’s function and source. The source is a function of the ambient fluid properties and surface shape. The surface shape is constructed with the use of the product of multiple Heaviside functions. The integral is evaluated for the planar oblique shock wave. The newly derived approach yields exactly the same solution as presented by Meyer. The new method represents a possible avenue to attack unsolved canonical fluid flow problems. |
Sunday, November 20, 2022 6:32PM - 6:45PM |
J10.00010: Steady, Quasi-One-Dimensional, Internal Compressible Flow with Area Change, Heat Addition, and Friction Andrew A Oliva, Scott C Morris An exact, closed-form solution is presented for internal compressible flows with an arbitrary combination of area change, heat addition, friction, and non-uniform flow. The approach assumes steady flow of a calorically perfect ideal gas using the integral form of the governing equations. It is shown that the equations reduce to a simple, bi-quadratic equation in exit Mach number. This solution is compared to previously known solutions for Rayleigh flow, Fanno flow, isentropic flow, and normal shock relations. Theoretical solutions for sudden expansion, sudden contraction, and supersonic-supersonic two-stream constant area mixing are also presented. These solutions were found to be in agreement with data available in the literature. |
Sunday, November 20, 2022 6:45PM - 6:58PM |
J10.00011: Multi-Scale Modeling of a Shock Tube to Examine Shock-Droplet Interaction Reed W Forehand, Khanh C Nguyen, Sydney Briggs, Nicolas Berube, Caroline J Anderson, Michael P Kinzel, Subith Vasu, Sheryl M Grace This effort presents a multi-physics, multi-scale approach to modeling the problem of shock-droplet interaction within a shock tube. The overall motivation of this study is to simulate a practical experiment that provides a similar mechanism that a rain droplet would experience when interacting with the bow shock of a reentry vehicle. The present work presents a multi-scale approach using a lower fidelity simulation of the entire shock tube to gain the boundary conditions of the test section, and provide a preliminary impact analysis while a higher fidelity simulation of the droplet explores phenomena such as breakup, cavitation, and evaporation. |
Sunday, November 20, 2022 6:58PM - 7:11PM |
J10.00012: Machine Learning with Supersonic Retropropulsion Wind Tunnel Test Data David Wu, Wai Tong Chung, Matthias Ihme, Karl Edquist Future human Mars missions will require powered descent starting at supersonic conditions, termed supersonic retropropulsion (SRP), because parachutes alone will not provide sufficient deceleration for landing human-scale payloads. We use machine learning (ML) methods to develop novel and innovative data-analytic methods to advance the fundamental understanding of multi-nozzle plume physics, quantify uncertainties, and inform planning for enabling the deployment of SRP technology. Overall, we analyze wind-tunnel test data for a wide range of input parameters and operating conditions. From the knowledge generated from the analysis of this data, robust and efficient physics-informed ML tools can be developed to support the design of SRP vehicles. |
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