Bulletin of the American Physical Society
72nd Annual Meeting of the APS Division of Fluid Dynamics
Volume 64, Number 13
Saturday–Tuesday, November 23–26, 2019; Seattle, Washington
Session A38: Porous Media Flow: Multiphase Flows |
Hide Abstracts |
Chair: Merlin Etzold, Cambridge Room: 620 |
Saturday, November 23, 2019 3:00PM - 3:13PM |
A38.00001: Controlling capillary fingering using pore size gradients in disordered media Nancy Lu, Christopher Browne, Daniel Amchin, Janine Nunes, Sujit Datta Capillary fingering is a displacement process that can occur when a non-wetting fluid displaces a wetting fluid from a homogeneous disordered porous medium. Here, we investigate how this process is influenced by a pore size gradient. Using microfluidic experiments and computational pore-network models, we show that the non-wetting fluid displacement behavior depends sensitively on the direction and the magnitude of the gradient. The fluid displacement depends on the competition between a pore size gradient and pore-scale disorder; indeed, a sufficiently large gradient can completely suppress capillary fingering. By analyzing capillary forces at the pore scale, we identify a non-dimensional parameter that describes the physics underlying these diverse flow behaviors. Our results thus expand the understanding of flow in complex porous media and suggest a new way to control flow behavior via the introduction of pore size gradients. [Preview Abstract] |
Saturday, November 23, 2019 3:13PM - 3:26PM |
A38.00002: Evolution of a liquid-liquid interface through a symmetric pore doublet model. Jonathan Siles Garner, Anchal Sareen, Ellen Longmire In applications such as oil recovery, diagnostics and printing, the displacement of one liquid from a porous medium is often achieved by injecting another liquid. In these situations, it is typically desired to minimize entrapment of the receding fluid in the pores. In this study, we investigate experimentally the liquid entrapment process as the liquid-liquid interface evolves through a quasi-two-dimensional pore doublet model. Experiments are performed for various Weber numbers (We) of the invading liquid for three flow geometries. The entrapped volume was found to increase significantly with increasing Weber number of the invading fluid. Beyond a `critical' We, when the inertia of the invading non-wetting liquid is high compared to the surface tension of the interface, the non-wetting liquid pierces through the pockets of the entrapped receding liquid leading to `instability'. It was also found that the entrapped volume can be reduced significantly by making the trailing edge of posts pointed. This geometry also delays the interface `instability' to higher We. Effects of the fluid viscosity ratio and We number of the invading fluid will be discussed in detail for three post geometries. [Preview Abstract] |
Saturday, November 23, 2019 3:26PM - 3:39PM |
A38.00003: Numerical Simulation of Immiscible Pore Scale Flow: Wettability and Dynamics Soheil Esmaeilzadeh, Zhipeng Qin, Amir Riaz, Hamdi Tchelepi Accurate characterization of fluid-fluid interfacial dynamics is crucial for modeling pore-scale multiphase flows common in water resources management and subsurface applications. In this work, we propose a framework to accurately capture the dynamics of the capillary dominated pore-scale fluid-fluid interfaces in the presence of complex-shaped confinements. The incompressible Navier-Stokes equations are coupled with a multiscale sharp-interface level-set method and a direct-forcing based immersed boundary approach on a cartesian mesh to capture the interfacial dynamics. With the viscous terms being treated semi-implicitly, and a dynamic contact-line model suited for curved surfaces, we study the effects of wettability, contact angles, and pinch-off dynamics. \\ Keywords: water resources management, pore-scale, level-set method, immersed boundary, multiphase flow [Preview Abstract] |
Saturday, November 23, 2019 3:39PM - 3:52PM |
A38.00004: Anisotropic wicking~ Sohyun Jung, Wonjung Kim, Ho-Young Kim Capillarity-driven wicking of liquids into porous substrates follows Washburn's rule, in general. Here we show that the wicking dynamics are substantially altered when the substrates are structurally anisotropic or soluble in the liquids. First, when the polymer fibers are aligned in one direction, the non-reactive liquid wicks fast along the direction of the fibers following Washburn's rule while the wicking still occurs across the fibers exhibiting a power law different from Washburn's rule. Second, when the polymer is soluble in the liquid, the wicking occurs dominantly across the fibers rather than along them, contrary to our intuition. We show that the rate of soluble wicking is determined by viscosity but independent of surface tension of the solution. [Preview Abstract] |
Saturday, November 23, 2019 3:52PM - 4:05PM |
A38.00005: Wicking-mediated drying in porous media Marta Gonçalves, Yeseul Kim, Jin Young Kim, Najaf Rubab, Takeshi Asai, Sungchan Hong, Byung Mook Weon When a water droplet is placed on a porous substrate, wicking and drying come up simultaneously. Wicking is a spontaneous liquid flow through porous media by capillarity and drying is a spontaneous vapor flow by vapor diffusion. Despite simultaneity of wicking and drying in porous media, how wicking affects drying is not clear yet. Here we study how wicking dynamics evolves with time and cooperates with drying dynamics by microscopic observations of water droplets on porous materials such as fabrics and papers. We find that wicking at early stages expands the surface area of absorbed water through porous materials, accelerating the evaporation rates. X-ray microscopy is a powerful tool to observe pore networks and water flows inside wicking fabrics. This result is useful to comprehend cooperation and to improve optimization between wicking and drying in porous media. [Preview Abstract] |
Saturday, November 23, 2019 4:05PM - 4:18PM |
A38.00006: Transpiration through hydrogels Merlin Aragon Etzold, M. Grae Worster, Paul F. Linden We present experiments and theory relating to transpiration through hydrogel beads in contact with a water reservoir below and evaporating into air above. Experimentally, we find that saturated hydrogel beads shrink until a steady state is reached in which water flows continuously through the beads. The size of the beads in steady state is very sensitive to the evaporation rate, which depends on the relative humidity and speed of the air, and is measurably sensitive to the pressure in the fluid reservoir. Specifically, the beads are smaller when the evaporation rate is larger or the reservoir pressure lower. Our conceptual 1D model proposes that transport in the hydrogel is driven by gradients in osmotic pressure, therefore by gradients in polymer concentration in the hydrogel, which correspond to gradients in swelling. If the evaporation rate or the bottom pressure changes, the adjustment of this gradient requires the bead to change shape. Smaller beads have larger gradients of osmotic pressure, which drive higher transpiration rates and can draw water against larger hydraulic heads. [Preview Abstract] |
Saturday, November 23, 2019 4:18PM - 4:31PM |
A38.00007: Carbonized sucrose-coated PDMS sponge for highly efficient and self-cleaning solar evaporator Jaehyeon Lee, Sang Joon Lee Solar steam generation is a promising technology for seawater desalination and water purification. However, most state-of-the-art technologies are expensive and suffer from insufficient solar-to-evaporation conversion efficiency and fouling problems, which limit their practical applications. Here, we propose a new superhydrophilic thermally-insulated macroporus membrane (STIMM) composed of carbonized sucrose and polydimethylsiloxane (PDMS) as an efficient solar evaporator. The coupled effect of superhydrophilicity and heat localization of STIMM was found to maximize the solar-to-evaporation conversion efficiency. The highest evaporation rate of 7.702 kg/h/m$^{\mathrm{2}}$, 8.7 times higher than that of only water, was achieved with solar-to-evaporation conversion efficiency of 99.8{\%}. The STIMM was applied to obtain pure drinkable water from saline water with 20 wt{\%} high salinity, with a 99.997{\%} desalination efficiency. In addition, the macro-pore size of STIMM enabled self-cleaning with 93.1{\%} of salt rejection rate, which mitigate the fouling problem substantially. The present results demonstrate a highly effective and sustainable solar steam generator, which would be applied for solar thermal desalination and water purification systems. [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