Bulletin of the American Physical Society
76th Annual Meeting of the Division of Fluid Dynamics
Sunday–Tuesday, November 19–21, 2023; Washington, DC
Session G20: Drops: Levitation |
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Chair: Ranga Narayanan, Department of Chemical Engineering, University of Florida Room: 146C |
Sunday, November 19, 2023 3:00PM - 3:13PM |
G20.00001: Viscosity & Surface Tension Measurement Using Resonance Of Levitated Molten Droplets Thomas Corbin, Jason Livesay, Robert Singiser, Nevin Brosius, Brandon Phillips, Michael Sansoucie, Ranga Narayanan This research investigates a novel method using Faraday instability on a spherical drop to measure viscosity and surface tension in liquid metals. These properties play a crucial role in modeling welding, in-situ space crystal growth, and additive manufacturing processes like Direct Energy Deposition (DED). By subjecting the drop to a periodic electric field matching its natural frequency, resonance is induced, leading to the formation of unique modal structures on the drop's surface. The study explores different analytical approaches to analyze these resonant features and highlights their advantages. Furthermore, experimental data for Zirconium and Tin are presented, demonstrating the applicability of the method to different liquid metals. |
Sunday, November 19, 2023 3:13PM - 3:26PM |
G20.00002: The effect of heat transfer in an evaporatiing liquid layer on the droplets levitating above it Jacob E Davis, Vladimir S Ajaev Studies concerning droplet interactions with liquid surfaces are important for a variety of applications, including spray cooling, aerosol drug distribution, and other particle transport problems. In this study, we consider a slowly condensing droplet levitating near the surface of an evaporating layer and develop a mathematical model to describe diffusion and heat transfer in the system. The method of separation of variables in bipolar coordinates is used to obtain the series expansions for temperature distribution in the air, droplet, and the liquid layer, as well as the vapor concentration. This framework, combined with the coupled boundary conditions at the interface, allows us to determine temperature profile and condensation rate at the surface of the droplet and the temperature profile on the surface of the liquid layer. From these findings, we can analyze the effect of the liquid layer on the droplet. On the layer surface under the droplet, there is a reduction in the rate of evaporation, possibly due to the constricting geometry of the problem. The temperature gradient along the layer surface leads to previously neglected Marangoni stresses. Their influence of the fluid flow is discussed. |
Sunday, November 19, 2023 3:26PM - 3:39PM |
G20.00003: Coalescence and mixing dynamics of droplets in acoustic levitation Koji Hasegawa, Kota Honda, Kota Fujiwara, Akiko Kaneko, Yutaka Abe Acoustic levitation is well-suited to 'lab-on-a-drop' contactless chemical analysis of droplets. Rapid mixing is of fundamental importance in lab-on-a-drop platforms and many other applications involving droplet manipulation. Small droplets, however, have low Reynolds numbers; thus, mixing via turbulence is not possible. Inducing oscillation on gas-liquid interface is effective in this regard, however, the relationship between internal flow and mixing dynamics of droplets remains unclear. In this study, we conducted a set of simultaneous optical measurements to assess both the flow field and the distribution of fluid components within acoustically levitated droplets. To achieve this, we developed a technique to selectively separate fluorescent particles within each fluid, permitting the measurement of the concentration field based on the data from the discrete particle distribution. This approach revealed a relationship between the mixing process and the internal flow caused by oscillations on the gas-liquid interface. Thus, the internal flow induced by droplet oscillation could enhance droplet mixing. Our findings will be conducive to the application and further development of lab-on-a-drop devices. |
Sunday, November 19, 2023 3:39PM - 3:52PM |
G20.00004: The elastic Leidenfrost effect: An interplay between vaporization rate, gas flow rate, and shape. Vicente Luis L Diaz Melian, Isaac Lenton, Scott R Waitukaitis When a liquid droplet comes near a hot surface, vaporization can become sufficient to cause the drop to levitate—this is the Leidenfrost effect [1]. Vaporizable soft solids, e.g., hydrogels, can also exhibit levitation [2] or, additionally, a sustained bouncing effect [3]. The interplay between vaporization rate, gas flow rate, and shape is essential for these behaviors, but the nature of this interaction is not fully understood. We address this open question using high-speed interferometric imaging [4] to measure the 2D height profile underneath a floating hydrogel sphere. |
Sunday, November 19, 2023 3:52PM - 4:05PM |
G20.00005: Abstract Withdrawn |
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