Bulletin of the American Physical Society
APS March Meeting 2018
Volume 63, Number 1
Monday–Friday, March 5–9, 2018; Los Angeles, California
Session R46: Drops and Bubbles II |
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Sponsoring Units: DFD Chair: Sujit Datta, Chemical and Biological Engineering, Princeton University Room: LACC 506 |
Thursday, March 8, 2018 8:00AM - 8:12AM |
R46.00001: Capillarity and convection-controlled assembly during the spreading of particulate suspensions on an air-liquid interface Rajesh Ranjan, Srishti Sehgal, Arun Ramachandran Recent literature has seen an explosion of studies on the spreading of fluids on an air-liquid interface; however, none have examined the spreading characteristics of two-phase fluid materials. In this work, a drop of a concentrated suspension of PMMA particles in silicone oil was placed on an aqueous glycerol solution – air interface. Depending on the initial rate of spreading of the suspension, two outcomes were observed: the particles were either swept away by the spreading suspension, or organized into an array of two-dimensional networks. Increasing the particle size, particle volume fraction, substrate viscosity and salinity were found to promote network formation. The observations can be explained as a balance between the spreading-induced hydrodynamic forces that separate the particles from each other, and capillary attraction forces which lead to particle aggregation on the interface. These results have potential applications in printing and coating technologies, and in biology. |
Thursday, March 8, 2018 8:12AM - 8:24AM |
R46.00002: Atomistic Calculations of Fluid-Fluid Interfacial Mobility Paul Barclay, Jennifer Lukes Liquid-liquid and liquid-vapor interfacial mobilities are calculated for the first time using equilibrium dual control volume grand canonical molecular dynamics. Mobility is calculated from one-dimensional random walks of the interface using three different methods based on interfacial position variance, interfacial mean squared displacement, and time-autocorrelation of the interfacial velocity. The mobilities calculated with all three methods show excellent agreement for both liquid-liquid and liquid-vapor systems indicating that any one of the calculation methods could be used to calculate the interfacial mobility. |
Thursday, March 8, 2018 8:24AM - 8:36AM |
R46.00003: Fluctuation assisted spreading of a fluid filled elastic blister Andreas Carlson In this theoretical and numerical study, we show how spatially extended fluctuations can influence and dominate the dynamics of a fluid filled elastic blister as is deforms onto a pre-wetted solid substrate. To describe the blister dynamics, we develop a stochastic elastohydrodynamic framework that couples the viscous flow, the elastic bending of the interface and the noise from the environment. We deploy a scaling analysis to find the elastohydrodynamic spreading law R ∼ t1/11 a direct analogue to the capillary spreading of drops, while the inclusion of noise in our model highlights that the dynamics speed-up significantly R ∼ t1/6 as local changes in curvature enhance the peeling of the elastic interface from the substrate. Moreover, our analysis identifies a distinct criterion for the transition between the deterministic and stochastic spreading regime, which is further illustrated by numerical simulations. |
Thursday, March 8, 2018 8:36AM - 8:48AM |
R46.00004: How surfactants mobilize oil trapped in a 3D porous medium Han-Jae Cho, Nancy Lu, Sujit Datta Surfactant solutions are promising candidates for enhancing oil recovery from subsurface reservoirs and promoting contaminant removal from groundwater aquifers. However, the mechanisms by which surfactants can mobilize a non-aqueous fluid trapped in a porous medium remain unknown. We use confocal microscopy to measure the flow field associated with oil mobilization by a surfactant solution in a transparent 3D porous medium. We find that the competition between surfactant adsorption, interfacial dilation/contraction, and the local Peclet number yields different forms of oil mobilization. These results could help better inform surfactant selection and design for flooding applications. |
Thursday, March 8, 2018 8:48AM - 9:00AM |
R46.00005: Hindered Coalescence in the Presence of Insoluble Surfactants Carolina Vannozzi For moderate capillary numbers, i.e. Ca=O(0.05÷0.3), simulations and theory for two viscous drops undergoing a flow induced head-on collision in a viscous matrix in the Stoke flow limit showed that coalescence is hindered, i.e. the film reached a steady state thickness hss. We analyze this phenomenon in the presence of insoluble surfactants both for high (C=60% Cmax, where Cmax is the maximum surfactant concentration) and low (C=1.6% Cmax) surfactant concentrations through the use of boundary integral calculations of the full drop problem, [1] . |
Thursday, March 8, 2018 9:00AM - 9:12AM |
R46.00006: Breakup dynamics of toroidal droplets in shear-thinning fluids Ekapop Pairam, Alexandros Fragkopoulos, Luka Marinkovic, Alberto Fernandez-Nieves Toroidal droplets are inherently unstable and transform into spherical droplets via the Rayleigh-Plateau instability for cylindrical jets. We exploit this similarity to study the break-up dynamics of a Newtonian liquid jet surrounded by rheologically non-linear materials. We find that break-up takes longer compared to break-up in the presence of simple fluids. Interestingly, the breakup dynamics can be explained by considering the linear theory for Newtonian liquids and incorporating the non-linearities of our material through the strain-rate-dependent viscosity. Finally, we show that the scaling factor required to relate the viscosity to the growth rate associated to the Rayleigh-Plateau instability is given by the elastic modulus of the outer material, illustrating that both the viscoelasticity and shear-thinning behavior of the outer material are essential in the dynamics of the problem. |
(Author Not Attending)
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R46.00007: Droplet breakup with in situ marangoni-induced elongational flow Margaux Kerdraon, Emilien Dilly, Stéphanie Descroix, Marie-Caroline Jullien Breaking unconfined droplets in an elongational flow has been investigated both theoretically |
Thursday, March 8, 2018 9:24AM - 9:36AM |
R46.00008: Evaporation of pointy ice drops: smoothing out the singularity Etienne Jambon-Puillet, Noushine Shahidzadeh, Daniel Bonn Although not as commonly observed as the evaporation of liquid water, ice does evaporate (or sublimate) below 0°C provided the surrounding air is sufficiently dry, i.e. with a relative humidity over ice below 100%. Through controlled experiments, we study the evaporation of sessile ice drops crowned with a conical tip: pointy ice drops. We show that, like liquid droplets, their evaporation is diffusion limited and strongly enhanced at sharp points: their edges and tip. However, unlike liquid droplets whose sharp edges are maintained by surface tension, the tip and edges of our pointy ice drop, originally sharp are quickly smoothed out. We accurately predict the whole drop evaporation using finite element simulations and present simple analytical results for the tip smoothing at short time and the evaporation of the latter smoothen ice drop. Our results being also applicable to diffusion limited dissolution, we expect them to be relevant in pharmaceutical applications. |
Thursday, March 8, 2018 9:36AM - 9:48AM |
R46.00009: Experimental dew condensation using radiative cooling Joachim Trosseille, Anne Mongruel, Laurent Royon, Daniel Beysens The increasing need of fresh water in the world and especially in arid regions led recently to seriously consider rain and dew precipitations as new source of water. Collecting rain water is simple, but harvesting dew is much challenging as it requires (i) cooling a surface below the dew point so that the vapor in the air condenses; (ii) tailoring the surface properties to promote water condensation and drainage. In order to reproduce and study this phenomenon, a commonly used way is to cool the substrate by contact. However the method has thermal and geometrical limitations and diverges from the natural phenomenon which involves radiative heat exchange. In order to reproduce radiative cooling in the laboratory a novel setup has been designed. It uses a cold plate at 200K exchanging heat with the substrate. The latter is set in a humidity-controlled chamber where heat exchange is made through a window transmitting 8-13 µm radiation. The device is then used to condense water on complicated shapes as needles, insects or curved surfaces what wouldn't be possible by contact cooling. This work will be concerned with basic questions on the influence of surface chemistry and efficiency of radiative cooling, and will explore the efficiency of this coupled strategy for water harvesting. |
Thursday, March 8, 2018 9:48AM - 10:00AM |
R46.00010: Droplets and droplet lattices on freely suspended smectic films in microgravity Ralf Stannarius, Torsten Trittel, Kirsten Harth, Christoph Klopp, Pavel Dolganov, Nikita Shuravin, Vladimir Dolganov, Eric Minor, Cheol Park, Joseph MacLennan Free-standing bubbles of smectic A liquid crystals with film thicknesses of few nanometers were explored under microgravity conditions on the International Space Station (ISS) to analyse the behaviour of liquid inclusions in the films. Microdroplets created in the films self-organize into nearly regular triangular lattices. We analyse the lattice parameters and droplet dynamics to understand fundamentals of hydrodynamics in quasi-twodimensional systems and to extract smectic material parameters. |
Thursday, March 8, 2018 10:00AM - 10:12AM |
R46.00011: Abstract Withdrawn |
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