Bulletin of the American Physical Society
71st Annual Meeting of the APS Division of Fluid Dynamics
Volume 63, Number 13
Sunday–Tuesday, November 18–20, 2018; Atlanta, Georgia
Session B38: Awards Session: Presentation of Awards and DFD Fellowships (Otto LaPorte Lecture, Stanley Corrsin Award, Francois Frenkiel Award, Andreas Acrivos Dissertation Award) |
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Chair: Eckart Meiburg, University of Califonia, Santa Barbara, Satish Kumar, University of Minnesota, S. Balachandar, University of Florida Room: Georgia World Congress Center Thomas Murphy Ballroom |
Sunday, November 18, 2018 10:20AM - 10:55AM |
B38.00001: PRESENTATION OF AWARDS AND FELLOWSHIPS
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Sunday, November 18, 2018 10:55AM - 11:40AM |
B38.00002: Otto LaPorte Lecture: Singularities in Fluid Dynamics Invited Speaker: Keith Moffatt Singularities of the Navier-Stokes equations occur when some (possibly high-order) derivative of the velocity field is infinite at any point of a field of flow (or, in an evolving flow, becomes infinite at any point within a finite time). Such singularities can be mathematical but unphysical (as e.g. in two-dimensional flow near a sharp corner) in which case they can be 'resolved' by improving the physical model considered; or they can be physical but non-mathematical (as e.g. in the case of cusp singularities at a fluid/fluid interface) in which case resolution of the singularity may involve incorporation of additional physical effects; such examples will be briefly reviewed. The 'finite-time singularity problem' for the Navier-Stokes equations will then be discussed and a new analytical approach will be presented; here it will be shown that there is indeed a singularity of the 'physical but non-mathematical' type, in that, at sufficiently high Reynolds number, vorticity can be amplified by an arbitrarily large factor within a finite time. In this case, the singularity is resolved by three-dimensional vortex reconnection in a manner that admits analytical description. Implications for turbulence will be presented. [Part of this work has been in collaboration with Yoshifumi Kimura.] |
Sunday, November 18, 2018 11:40AM - 12:25PM |
B38.00003: Stanley Corrsin Award Talk: Hairy Hydrodynamics Invited Speaker: Anette E. Hosoi Flexible slender structures in flow are everywhere. While a great deal is known about individual flexible fibers interacting with fluids, considerably less work has been done on fiber ensembles — such as fur or hair — in flow. These hairy surfaces are abundant in nature and perform multiple functions from thermal regulation to water harvesting to sensing. Motivated by these biological systems, we consider several examples of hairy surfaces interacting with flow including drinking bats and diving sea otters. In the first example we consider viscous dipping, a feeding method utilized by many nectar drinking animals. This mechanism is reminiscent of Landau-Levich-Derjaguin (LLD) dip coating, and has been analyzed through the LLD framework in previous studies. However, many viscous dippers have hairy structures on their tongues that enhance fluid uptake. In this study, we investigate the impact of mesoscale hairy structures on feeding efficiency. In the second example, we take inspiration from semi-aquatic mammals (such as fur seals, otters, and beavers) which have specially adapted fur that serves as an effective insulator both above and below water. Many of these animals have evolved pelts that naturally entrap air when they dive. Here we investigate diving conditions and fur properties which amplify air entrainment. |
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