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 A07: Nanoflows: Complex Systems |
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Chair: Dimitrois Papavassiliou, University of Oklahoma Room: Georgia World Congress Center B212 |
(Author Not Attending)
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A07.00001: Abstract Withdrawn
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Sunday, November 18, 2018 8:13AM - 8:26AM |
A07.00002: Ion-Selective Transport and Osmotic Power Generation in Boron-Nitride Membranes with Non-overlapping Double Layers Semih Cetindag, Aaditya Pendse, Doo Sung Hwang, Sanjay Behura, Vikas Berry, Sangil Kim, Jerry W Shan Hexagonal boron nitride (h-BN) membranes, which develop high surface charge in basic solutions, are of interest for various potential applications, including osmotic power generation, highly efficient filtering and separation processes. Here, we investigate ion transport and power generation in macroscopic h-BN nanopore membranes (BN-AAO) fabricated from anodized alumina (AAO) templates. Despite the relatively large pore diameter of 30 nm, the BN-AAO membranes show highly selective transport, with electrophoretic transport rates differing by a factor of ~74.5 between positively and negatively charged fluorescent ions (NDS(-2) vs Ru(bpy)(+2) ) at pH=10. The membranes also show high osmotic power densities in the range of 27-99 W/m2, based on the open pore area, for a KCl molarity difference across the membrane of CH/CL = 1000/1 mM at pH=11. The ion selectivity and osmotic power generation are correlated to each other, and both drop with decreasing surface-charge density at lower pH. However, conductance tests suggest that an improved theoretical model, considering the concentration-dependent surface charge, may be needed to correctly estimate the surface charge of h-BN nanochannels. We conclude by comparing the BN-AAO membranes with similar selective ion-transport systems. |
(Author Not Attending)
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A07.00003: Abstract Withdrawn
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Sunday, November 18, 2018 8:39AM - 8:52AM |
A07.00004: Characterization and Manipulation of Single Nanoparticles Using Electrokinetic Trapping Near Nanopores Rami Yazbeck, Chuanhua Duan Manipulation and detection of micro/nanoparticles are of great importance in a broad spectrum of applications ranging from medical diagnostics and environmental monitoring to basic research in physics and biology. Although a variety of methods that can selectively trap and detect microparticles have been developed over the last decade, it remains a great challenge to extend these methods to the nanoscale. Here we report a new approach for single nanoparticle manipulation and detection based on electrokinetic trapping of nanoparticles near a low-aspect ratio nanopore. We discover that this trapping results from a balance between electrophoretic and electroosmotic forces and that the motion of a trapped nanoparticle can be modeled as a harmonic oscillator. We demonstrate that, by analyzing ionic current through the nanopore, it is possible to characterize the size and surface charge density of the trapped nanoparticle. We also demonstrate that the position of trapping and force exerted on the nanoparticle can be easily tuned by changing the applied voltage. We envision that further development of this technique will enable various advanced tools for drug delivery, transport control, and biosensing.
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Sunday, November 18, 2018 8:52AM - 9:05AM |
A07.00005: Emulsion Formation using Surfactants and Nanoparticles under Shear Tuan V Vu, Dimitrios V Papavassiliou In enhanced oil recovery (EOR) surfactant solutions are pumped into a reservoir to mobilize trapped oil [1]. Recently, the potential of Janus nanoparticles has also been studied for use in EOR [2]. Here, the formation of emulsions using dissipative particle dynamics (DPD) simulations and the effects of shear on oil mobilization are studied. Oil is represented by hexadecane [3] that is adsorbed on the wall of a microcavity in an aqueous environment. The system is then sheared in a Couette flow simulation. Without surfactant, the oil cannot be mobilized, but with the presence of sodium dodecyl sulfate surfactants the oil detaches from the solid surface to create oil-in-water emulsion. Increasing the surfactant concentration leads to a reduction of the required shear rate, as does a hydrophilic solid wall. The formation of Pickering emulsions by using Janus nanoparticles is also investigated, as are the synergetic effects of Janus particles and surfactants. REFERENCES 1. Green DW, Willhite GP, Enhanced oil recovery. Vol. 6. 1998: Society of Petroleum Engineers Richardson, TX. 2. Negin C, Ali S, Xie Q, Petroleum, 2016. 2(4): p. 324-333. 3. Vu T., Papavassiliou DV, J. Chem. Phys., 2018. 148(20): Art. 204704 |
(Author Not Attending)
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A07.00006: Direct visualization of fluid behaviors at the nanoscale for shale gas/oil fundamentals, challenges and applications Junjie Zhong, David Sinton Hydrocarbon recovery from shale provides an increasing share of energy. These resources are multi-component fluid mixtures within multi-scale geometries, and understanding their fluid behaviors presents an array of challenges for experimentalists, theorists and operators. Here, we present our recent progress in visually quantifying fluid behaviors down to a few nanometers scale through nanofluidic device. During the gas production, we find the fluid phase behavior is highly governed by the gas flow in nanoconfinement, a case beyond bulk understanding. The vapor flow at a Knudsen number between 0.01 to 1 is of shale relevance. We also quantify the multiphase flow and interactions in nanoconfinement. An important application of this fundamental issue is the enhanced oil recovery strategies for tight oil reservoirs. With nanofluidic device, we have directly visualized and studied factors affecting immiscible gas fingering and miscible gas filming into liquid oil in nanoporous media, indicating fundamental challenges as well as potentials of gas-based enhanced oil recovery strategies in nanoporous shale. The nanofluidic approach presented here is not limited to probing oil-gas relevant features, but also a platform for studying fluid behaviors in nanoporous material. |
(Author Not Attending)
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A07.00007: Molecular dynamics study of capillary wave damping by monolayer films at the air-water interface Hui Zhang, Kun Zhou, Adrian Wing-Keung Law Capillary waves (CW, wavelength ≤ 1 cm) at the air-water interface are governed by the restoring force of surface tension with damping by viscous dissipation. Long-chain amphiphiles can form a monolayer film via self-assembly at the water surface. The viscoelastic behaviour of monolayers can affect the CW frequency and damping coefficient in a dynamic manner. Previous studies which relied on light scattering techniques and hydrodynamic theories were able to study the CW damping by monolayers down to the wavelength of several microns. However, at the nanoscale, lacking suitable experimental techniques, the validity of the hydrodynamic description on CW damping by monolayers remains unknown. In this study, the CW damping effect of monolayers are investigated using molecular dynamics (MD) simulations. The time correlation of interfacial profiles are collected under the influence of palmitic acid (C16H32O2) monolayer. The monolayer phase transition and viscoelastic properties are examined, and the validity of hydrodynamic theory at the nanoscale is discussed. |
Sunday, November 18, 2018 9:31AM - 9:44AM |
A07.00008: Nanoscale Cavitation in perforation of cellular membrane by shock-wave induced nanobubble collapse Nan Nan, Dongqing Si, Guohui Hu The collapse of the bubble induced by the shock wave leads to nano-jet, which is able to perforating cellular membrane. This phenomenon is investigated by Martini coarse-grained molecular dynamic (CG-MD) simulations in the present study. It is found that the occurrence of cavitation nucleation at the nanoscale can be observed during the perforating process. The cavitation locates near the puncture of the cell membrane and its ultimate evolutionary form presents a ring-like structure. The volume of the cavitation is calculated for different initial bubble size, and it is found that the maximum volume of the cavitation area has a correlation with the initial bubble size. To understand the underlying physics of the cavitation phenomenon, the classical nucleation theory based on the Rayleigh-Plesset equation is applied to the non-equilibrium nanoscale system after the pressure field is obtained by using Irving-Kirkwood-Noll procedure. The consistence between the results of CG-MD and the theory reveals that the average pressure of the local environment plays a crucial role in cavitation occurrence on the non-equilibrium system subjected to strong inertia, e.g., shock wave and nano-jet. |
Sunday, November 18, 2018 9:44AM - 9:57AM |
A07.00009: Capacitive effects and transport in nanofluidic diodes Olivier Liot, Rudy Saulnier, Gilles Simon, Remy Fulcrand, Anne-Laure Biance Nanofluidics has been an emergent topic during the last decade (Bocquet et al., 2010). Because of the huge increase of surface/volume ratio, the surface electrokinetic effects could have a strong impact in the recovery of osmotic energy (van der Heyden et al., 2006). In addition, experimental works have shown that it is possible to build nanofluidic diodes using nanopores whose surface charge is not uniform (Karnik et al., 2007). A current rectification, typical of semi-conductor diodes, is observed when a potential difference is applied to nanochannels. An intrinsic aymmetry of the electrochemical potential causes this effect (Vlassiouk et al., 2007). Moreover, the dimensions of nanopores compared to the electrical double layer can lead to concentration-polarization layers with ions accumulation inside the pore or at its entrance (Dlugolecki et al., 2010), phenomena which could be promoted by surface charge discontinuity. |
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