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 B03: Aerodynamics: Vehicles |
Hide Abstracts |
Chair: Peng Zhang, NYU Room: 201 |
Saturday, November 23, 2019 4:40PM - 4:53PM |
B03.00001: Optimization of a highway infrastructure design through a combined computational fluid dynamics and evolutionary algorithm framework Peng Zhang, Anh-Vu Vo, Debra Laefer, Maurizio Porfiri Design of highway infrastructure significantly influences the performance and fuel consumption of vehicles. However, standard design practice heavily relies on empirical knowledge, based on difficult-to-generalize and cost-prohibitive experiments. Here, we propose a global optimization framework based on computational fluid dynamics (CFD) and evolutionary algorithms to identify the optimal design of a highway infrastructure that minimizes aerodynamic drag on moving vehicles. Although the framework is broadly-applicable, we investigate the design using an actual section of highway with vertical side walls. The highway's geometry was captured by terrestrial laser scanning and is used to generate the computational domain for three-dimensional CFD. The drag on the vehicles is estimated through CFD using a k-$\varepsilon $ turbulence model. Reduction in the aerodynamic drag is attained by enhancing the interaction between the vehicles and the vertical side walls through the addition of solid slabs to the walls. The optimization process is performed through an evolutionary algorithm, which iteratively evolves the size and positioning of the added slabs toward an optimal design. Our results demonstrate that the proposed computational framework can inform future highway infrastructure designs. [Preview Abstract] |
Saturday, November 23, 2019 4:53PM - 5:06PM |
B03.00002: Unsteady Aerodynamics of Roll-Tacking and Roll-Gybing in an Olympic Class Sailboat Sarah Morris, C. H. K. Williamson In this research, we study unsteady sail motion techniques used by Olympic sailors to increase sailboat propulsion. One such technique is for sailors to use bodyweight movements to roll the boat about its longitudinal axis. This motion is used especially for turning the boat in light winds, by either ``roll-tacking'' (upwind sailing) or ``roll-gybing'' (downwind sailing). When roll-tacking and roll-gybing, sailors dynamically roll the boat to increase their speed and propel their boats faster than using wind alone; this is in contrast to flat-tacking and flat-gybing, wherein the sailor keeps the boat level (and mast vertical) while turning. Each of these motions is characterized in on-the-water experiments using a Laser sailboat equipped with a GPS, IMU, wind sensor and GoPro camera array. Bringing these motions into the laboratory, we study the underlying vortex dynamics that are responsible for generating extra propulsion in roll-tacking and roll-gybing. [Preview Abstract] |
Saturday, November 23, 2019 5:06PM - 5:19PM |
B03.00003: Effect of Hybrid-Heave Motions on the Lift of Oscillating Airfoils Jay Young, Sarah Morris, C. H. K. Williamson Inspiration for a number of unsteady airfoil dynamics studies has been drawn from animal locomotion. In the present research, we instead employ a sports-mimetic approach, studying unsteady airfoil motions inspired by sail dynamics. One such technique is ``sail flicking,'' whereby sailors use their bodyweight motion to roll the boat about its longitudinal axis, flicking the sail periodically. Because sailors do not sail directly into the wind, the boat travels at an angle relative to the apparent wind it experiences. A ``flicking'' sail will therefore oscillate at non-perpendicular angles to the incoming flow, in a motion we call ``hybrid-heave.'' We study these hybrid-heave motions with a NACA 0012 airfoil. We find both a ``high-lift'' and low-lift'' mode. The high-lift mode delivers significant lift increase compared to that of a static airfoil. We study the case of the two distinct modes in terms of instantaneous angle of attack, speed, and vortex dynamics. [Preview Abstract] |
Saturday, November 23, 2019 5:19PM - 5:32PM |
B03.00004: Effect of Spherical Depressions on Hatchback Cars: A CFD Study Sourajit Bhattacharjee, Vishesh Kashyap, Priyanshu Mittal, B.B. Arora A major reason for the development of form drag is vortices generated due to flow separation. This greatly affects the aerodynamics of light vehicles such as hatchback cars. Flow separation may be delayed by the creation of spherical depressions at various locations on the vehicle body, which could lead to a decrease in the form drag. Through a series of studies, the effect of spherical depressions of aspect ratios 2, 4, 6 and 8 was studied separately on the bonnet, doors and roof of a generic hatchback car. 3-D CFD analyses were performed using ANSYS Fluent using a validated computational model. The trends for drag force and drag coefficient with aspect ratio were observed to vary with change in the location of the depressions. While an aspect ratio of 4 delivered the greatest decrease in drag for the bonnet, an increasing trend was observed for the other 2 locations. At higher aspect ratios, the drag was observed to be higher than for the car without depressions. The studies demonstrated the effect of spherical depressions on hatchback cars and elaborated on the importance of location as well as aspect ratio as factors to be considered for low aerodynamic drag. [Preview Abstract] |
Saturday, November 23, 2019 5:32PM - 5:45PM |
B03.00005: Aerodynamic Assessment of Cross-Wind Airwake Characteristics at Ship Helodeck: A Simplified Approach Shrish Shukla, S. N. Singh, S. S. Sinha, R. Vijayakumar The combined ship-helicopter operation nearby small naval vessels has historically been one of the most challenging tasks. The complexity of this task primarily depends on the ship superstructure, helicopter aerodynamics, and cross-wind conditions. An early assessment of the overall airwake characteristics is one of the challenging tasks. The First-Of-Class Flying Trials are one of the most common methods to assess the resultant flow characterises over helodeck. These trials are conducted post-construction of the ship and mainly based on qualitative ratings of the test pilot. Also, a wide range of wind conditions cannot be covered, and the scope of further design modification is limited. Thus, there is a strong need to assess the impact of cross-wind conditions on the ship helodeck at the initial design stages. We present an early-stage simplified approach to estimate the aerodynamic impact of cross-winds over ship helodeck with reasonable accuracy. A Reynolds-averaged-Navier-Stokes based parametric analysis has been conducted for six cross-wind conditions to understand the cross-wind phenomena over a simplified frigate ship helodeck. The paper reports the cross-wind airwake assessment based on the criteria set developed by mean velocity gradients and turbulence intensity. [Preview Abstract] |
Saturday, November 23, 2019 5:45PM - 5:58PM |
B03.00006: Busemann-Sears-Haack hybrid geometries applied toward supersonic vehicles for improved wave drag performance Andrew Sklar, Zvi Rusak We present a new configuration for supersonic aircraft fuselages. It is first demonstrated that the commercial Fluent code provides mesh converged, valid results for inviscid supersonic flows around various configurations compared to classical predictions. Then, by adapting a hybrid geometry of the Busemann biplane shape to a span-wise split Sears-Haack body in the region between the bodies, we present a physically feasible two-body configuration that reduces shock wave interference between the two bodies and lowers the wave drag per volume of a given fuselage volume and length. The reduction is about $50\%$ when compared to the Sears-Haack body with same volume and length. In addition, when applied to non-enclosed geometries, the Busemann biplane experiences none of the wave drag spikes and hysteresis that were found with biplanes in prior studies, while maintaining its efficacy. Preliminary studies into effects of viscosity for supersonic flows at high Reynolds numbers show that the total drag is limited to $25\%$ greater than inviscid flow results. This effect has also been extended to a triple body configuration, which further cuts the drag per volume to less than $40\%$ of the equivalent Sears-Haack body. [Preview Abstract] |
Saturday, November 23, 2019 5:58PM - 6:11PM |
B03.00007: String Stability in Energy-Saving Formation Flight Philippe Chatelain, James Riehl, Esteban Hufstedler, Julien Hendrickx Formation flight of fixed-wing aircraft provides the opportunity to save substantial energy by exploiting the upwash created by vortical wakes. For the most efficient flight, the aircraft need to carefully track the relative wake position of their leader, which may move due to turbulence or maneuvering of the leader. The tracking errors may grow as the disturbances propagate to aircraft further downstream, resulting in `string instability'. This is more commonly examined in automobile platoons, and has not been adequately examined with respect to efficient aircraft formations. We discuss some pitfalls and trade-offs involved in designing string stable controllers for this system, and describe a controller that achieves both string stability and energy efficiency. [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