Bulletin of the American Physical Society
2017 Fall Meeting of the APS Prairie Section
Saturday–Sunday, November 11–12, 2017; University of Illinois at Chicago, Chicago, Illinois
Session D1: Session D |
Hide Abstracts |
Chair: Zhenyu Ye, University of Illinois at Chicago Room: UIC Student Center East 302 |
Sunday, November 12, 2017 10:30AM - 10:42AM |
D1.00001: Fluid--Structure Interaction Between a Power-Law Fluid and a Deformable Microtube or Microchannel Vishal Anand, Ivan Christov Microfluidic devices are made of soft materials, which leads to significant deformation even for ``slow'' flows of viscous fluids within. This deformation affects the flow rate versus pressure drop correlation, compared to the ideal case of Hagen--Poiseuille flow. We study the steady fluid flow and the concomitant structural deformation problem for a shallow cylindrical microtube as well as a slender rectangular microchannel. In both cases, having biofluid mechanics applications in mind, the non-Newtonian fluid behavior is modeled by the power-law fluid model to account for a shear-rate dependent viscosity. The fluid--structure coupled problem is solved analytically using a perturbation expansion. A consistency check is performed by comparing the initial results with those of a Newtonian fluid obtained by Fung (1993) and Christov et.\ al.\ (2017). It is seen that for the case of microtubes, the flow rate can be expressed as an explicit function of the pressure and the power-law exponent, while for the case of microchannels, it is possible to find the flow rate as a function of pressure for only specific values of the power-law exponents. We show this is a result of the non-trivial differences between the governing equations of static deformation of thin plates and shells. [Preview Abstract] |
Sunday, November 12, 2017 10:42AM - 10:54AM |
D1.00002: Binary gas mixture in a high speed channel Dr. Sahadev Pradhan The viscous, compressible flow in a 2D wall-bounded channel, with bottom wall moving in? the positive $x-$direction, simulated using the direct simulation Monte Carlo (DSMC) method,? has been used as a test bed for examining different aspects of flow phenomenon and separation performance of a binary gas mixture at Mach number \textit{Ma }$=$\textit{ (U\textunderscore w / }$\backslash $\textit{sqrt(}$\gamma $\textit{ k\textunderscore B T\textunderscore w /m)?) }in the range\textit{0.1 \textless Ma \textless 30}, and Knudsen number \textit{Kn }$=$\textit{ 1/(}$\backslash $\textit{sqrt(2) }$\pi $\textit{ d\textasciicircum 2 n\textunderscore d H)}in the range? \textit{.1 \textless Kn \textless 10}. The generalized? analytical model is formulated which includes the fifth order differential equation for the? boundary layer at the channel wall in terms of master potential ($\chi )$, which is derived? from the equations of motion in a 2D rectangular $(x - y)$coordinate. The starting point? of the analytical model is the Navier-Stokes, mass, momentum and energy conservation? equations in the $(x - y)$coordinate, where $x$and $y$are the streamwise? and wall-normal directions, respectively. The linearization approximation is used ((Pradhan {\&} Kumaran\textit{, J. Fluid Mech -}); (Kumaran {\&} Pradhan, \textit{J. Fluid Mech -})), where the equations of motion are truncated at linear order in the velocity and pressure perturbations to the base flow, which is anisothermal compressible Couette flow. Additional assumptions in the? analytical model include high aspect ratio \textit{(L \textgreater \textgreater H)}, constant temperature in the base state (isothermal condition), and low? Reynolds number (laminar flow). The analytical solutionsare compared with direct simulation Monte Carlo (DSMC) simulations and found good agreement (with a difference of less than 10{\%}), provided the boundary conditions are accurately incorporated in the analytical solution. [Preview Abstract] |
Sunday, November 12, 2017 10:54AM - 11:06AM |
D1.00003: Weakly Nonlinear Computational Analysis on Viscous Fingering in Tapered Hele-Shaw Cells Daihui Lu, Ivan Christov We present a theoretical and numerical study on the stability of immiscible viscous fingering in tapered Hele-Shaw cells across a range of capillary numbers ($Ca$), which measure the relative significance of the fluid's viscous forces to the interface's surface tension. The simulations are carried out using the InterFoam solver in the OpenFOAM, which solves the incompressible Navier-Stokes equations in each fluid, and couples the two through interfacial boundary conditions. We consider two cells: a diverging cell with a depth gradient $\alpha=3\times 10^{-3}$ and a converging cell with $\alpha=-1.5\times 10^{-3}$. We find in the diverging case the finger's growth rate is always positive. However, in the converging case there are three regimes depending on $Ca$. For small $Ca$, the growth rate is negative, which stabilizes the finger; for moderate $Ca$, the growth rate is negative first and then positive; for large $Ca$, the growth rate is positive. We explain this change through a local $Ca$, which is increasing along the flow direction in a converging cell. We also find in the high-$Ca$ regimes, the interface is relatively destabilized in the converging cell and stabilized in the diverging cell. We compare our simulations to recent experiments in the literature. [Preview Abstract] |
Sunday, November 12, 2017 11:06AM - 11:18AM |
D1.00004: Reconciling differences between Lipid transfer in free-standing and solid supported membranes: a time resolved small angle neutron scattering study. Benny Wah, Jeffrey Breidigan, Joseph Adams, Li Ge, Piotr Horbal, Sumit Garg, Lionel Porcar, Ursula Perez-Salas The membranes of animal cells have significant variation in the lipid and protein composition. If it weren't for the active work of proteins that maintain most of these variations, membranes would ultimately homogenize throughout by mixing. It has been long been recognized that the study of the passive movement of lipids between and within membranes can provide insight into this energetic toll. Using small angle neutron scattering, a non-invasive in situ technique, we recently demonstrated that tags or small structure changes in the lipids can have a huge effect on their transport characteristics. In the present study we compare lipid transfer and energetics between supported and free standing membranes. We find that exchange and flipping process are comparable while the presence of the surface slightly increases inter and intra-membrane transport rates. The activation energies for exchange appear to be nearly unaffected by the presence of the surface while for flip-flop it slightly increases. Our results strongly suggest that the geometry of the vesicles is responsible the apparent contradicting behavior previously reported between supported flat membrane systems and in free-standing membranes. [Preview Abstract] |
Sunday, November 12, 2017 11:18AM - 11:30AM |
D1.00005: First-principles study of interaction of silicene with amino acid analogues in solvated phase Yesukhei Jagvaral, Haiying He, Ravindra Pandey We have investigated the nature of adsorption of amino-acid analogues on silicene employing density functional theory and an implicit solvation model. Amino acid analogues are defined as CH3--R molecules, where R is the functional group of the amino acid side chain. We have found from the calculated results three distinct groups within the amino-acid analogues considered: (i) group I, which includes MeCH3 and MeSH, interacts with silicene via the van der Waals dispersive terms leading to physisorbed configurations; (ii) group II strongly interacts with silicene forming Si--O/N chemical bonds in the chemisorbed configurations; and (iii) group III, which consists of the phenyl group, interacts with silicene via $\pi $--$\pi $ interactions leading to physisorbed configurations. The results show that the lateral chains of the amino acids intrinsically determine the interactions between protein and silicene at the interface under the given physiological conditions. [Preview Abstract] |
Sunday, November 12, 2017 11:30AM - 11:42AM |
D1.00006: Enhancing rare earth ion luminescence using semiconducting nanoparticles P K Babu, Saisudha Mallur Glasses doped with rare earth (RE) ions are interesting optical systems due to their potential applications in solid state lasers, optical telecommunication, non-linear optical materials, electro-optic devices and, photovoltaics. They provide chemically stable and optically favorable environment for the lasing action of RE ions. Enhancing the fluorescence properties of RE ions is highly desired to make them suitable for these applications. For example, a large stimulated emission cross section ($\sigma_{p})$ is essential for an efficient laser transition. Among several factors that can influence $\sigma_{p}_{\mathrm{,}}$ the most important one is the immediate chemical environment of the RE ions. Therefore, to improve the efficiency of fluorescence transitions, one must produce favorable changes to the chemical environment of RE ions either by varying the base glass composition and/or doping the glass with metal/semiconducting nanoparticles (NPs). In this work, we show that when CdSe and ZnSe NPs are present in Sm-doped borate glasses, $\sigma_{p}$ of Sm$^{\mathrm{3+}}$ ions is considerably enhanced. Details about creating and controlling the growth of NPs inside a glass matrix will also be presented. [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