Bulletin of the American Physical Society
69th Annual Meeting of the APS Division of Fluid Dynamics
Volume 61, Number 20
Sunday–Tuesday, November 20–22, 2016; Portland, Oregon
Session R15: Bio: Pumping/Bacterial Oil Remediation |
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Chair: Jian Sheng, Texas A&M University Room: E143/144 |
Tuesday, November 22, 2016 1:30PM - 1:43PM |
R15.00001: Drinking with a hairy tongue: viscous entrainment by dipping hairy surfaces Alice Nasto, Pierre-Thomas Brun, José Alvarado, John Bush, Anette Hosoi Nectar-drinking bats have tongues covered with hair-like papillae, enhancing their ability to take up viscous nectar by dipping. Using a combination of model experiments and theory reminiscent of Landau-Levich-Derjaguin dip coating, we rationalize this mechanism of viscous entrainment in a hairy texture. For the model experiments, hairy surfaces are fabricated using laser cut molds and casting samples with PDMS elastomer. Modeling the liquid trapped within the texture using a Darcy-Brinkman like approach, we derive the drainage flow solution. The amount of fluid that is entrained is dependent on the viscosity of the fluid, the density of the hairs, and the dipping speed. We find that there is an optimal hair density to maximize fluid uptake. [Preview Abstract] |
Tuesday, November 22, 2016 1:43PM - 1:56PM |
R15.00002: A fully coupled bolus-esophageal-gastric model for esophageal emptying based on the immersed boundary method Wenjun Kou, John E. Pandolfino, Peter J. Kahrilas, Neelesh A. Patankar In this work, we develop a fully coupled bolus-esophageal-gastric model to study esophageal emptying based on the immersed boundary method. The model includes an esophageal segment, an ellipsoid-shaped stomach, and a bolus. It can easily handle the passive and active function of the lower esophageal sphincter (LES). Two groups of case studies are presented. The first group is about the influence from tissue anisotropy. Simulation shows that the weaker (or more compliant) part suffers from a higher wall shear stress and higher pressure load when the bolus is filled in and emptied from the LES segment. This implies a degradation cycle in which a weaker tissue becomes much weaker due to an increased load, a possible pathway to the esophageal lower diverticulum. The second group is about bulge formation resulting from asymmetric anatomy and a compliant LES. In particular, we find a right bulge tends to develop for a compliant LES. The bulge is most pronounced with a highest stiffness of the gastric wall. This implies that the competition between the LES stiffness and gastric wall stiffness might be another factor related to the esophageal lower diverticulum. [Preview Abstract] |
Tuesday, November 22, 2016 1:56PM - 2:09PM |
R15.00003: Pore Water Pumping by Upside-Down Jellyfish Manikantam Gaddam, Arvind Santhanakrishnan Patchy aggregations of Cassiopea medusae, commonly called upside-down jellyfish, are found in sheltered marine environments with low-speed ambient flows. These medusae exhibit a sessile, non-swimming lifestyle, and are oriented such that their bells are attached to the substrate and oral arms point towards sunlight. Pulsations of their bells are used to generate currents for suspension feeding. Their pulsations have also been proposed to generate forces that can release sediment locked nutrients into the surrounding water. The goal of this study is to examine pore water pumping by Cassiopea individuals in laboratory aquaria, as a model for understanding pore water pumping in unsteady flows. Planar laser-induced fluorescence (PLIF) measurements were conducted to visualize the release of pore water via bell motion, using fluorescent dye introduced underneath the substrate. 2D particle image velocimetry (PIV) measurements were conducted on the same individuals to correlate PLIF-based concentration profiles with the jets generated by pulsing of medusae. The effects of varying bell diameter on pore water release and pumping currents will be discussed. [Preview Abstract] |
Tuesday, November 22, 2016 2:09PM - 2:22PM |
R15.00004: Flow Dynamics of a smart pump: Mytilus Galloprovincialis Karem Pekkan, Fazil Uslu Hydrodynamic performance of marine mussel, Mytilus Galloprovincialis, is studied by the time-resolved particle image velocimetry (PIV). We evaluated inhalant flow, exhalant jet flow, pumping performances, and flow control capabilities of the mussels quantitatively. Inhalant flow structures of mussels are measured at the coronal plane first-time in literature. Nutrient fluid is convected into the mussel by three-dimensional sink type flow that is different than exhalant jet flow. Inhalant velocity reaches its highest magnitude inside of the mussel mantle while accelerating outward the mussel. We calculated pressure gradient at the coronal plane where three-dimensional sink type inhalant flow is observed. As inhalant flow approaches mussel shell tip, suction force generated by the inhalant flow increases. Likewise, unique exhalant jet flow regimes are studied for 17 mussels. Mussels can control their exhalant jet flow structure from single potential core region to double one or vice versa. Peak exhalant jet velocity generated by the mussels changes between 2.77 cm/s and 11.1 cm/s as a function of mussel cavity volume. Hydrodynamic dissipation at sagittal plane is calculated to evaluate whether there is any interference between inhalant sink flow and exhalant jet flow or not. Results showed an efficient synchronized pumping mechanism. This pumping mechanism can feature flow-turning angle, the angle between inhalant and exhalant jet flow, 90\textdegree with standard deviation of 16\textdegree . [Preview Abstract] |
Tuesday, November 22, 2016 2:22PM - 2:35PM |
R15.00005: The effect of resonant driving and damping on dynamic suction pumping Nicholas Battista, Laura Miller Impedance pumping (or dynamic suction pumping) drives flow through a a flexible valveless tube with a single region of actuation. It is a profoundly complex pumping mechanism given that the flow velocities and directions generated depend nonlinearly upon the driving frequency, material properties, duty factor, and location of the actuation point. Given the simplicity of its actuation, it is used in biomedical devices and is thought to generate flow in a number of biological systems. In this study, we numerically simulate an elastic tube with mass using the immersed boundary method and explore the performance when it is driven over a range of frequencies and damping factors. Flow is maximized during resonance, and bulk transport is minimal when the tube is over-damped. [Preview Abstract] |
Tuesday, November 22, 2016 2:35PM - 2:48PM |
R15.00006: The effect of lymphatic valve morphology on fluid transport Alexander Alexeev, Matthew Ballard, Zhanna Nepiyushchikh, Brandon Dixon The lymphatic vasculature is present in nearly all invertebrate tissue, and is essential in the transport of fluid and particles such as immune cells, antigens, proteins and lipids from the tissue to lymph nodes and to the venous circulation. Lymphatic vessels are made of up a series of contractile units that work together in harmony as ``micro hearts'' to pump fluid against a pressure gradient. Lymphatic valves are critical to this functionality, as they open and close with the oscillating pressure gradients from contractions, thus allowing flow in only one direction and leading to a net pumping effect. We use a hybrid lattice-Boltzmann lattice spring model which captures fluid-solid interactions through two-way coupling between a viscous fluid and lymphatic valves in a section of a lymphatic vessel to study the dynamics of lymphatic valves and their effect on fluid transport. Further, we investigate the effect of variations in valve geometry and material properties on fluid pumping. This work helps to increase our understanding of the mechanisms of lymphatic fluid transport, which has implications in a variety of pathologies, including cancer metastasis, autoimmunity, atherosclerosis and obesity. [Preview Abstract] |
Tuesday, November 22, 2016 2:48PM - 3:01PM |
R15.00007: Experimental Fluidic Investigation of Degradation of Pico-liter Oil Droplets by Physical and Biological Processes Maryam Jalali, Jian Sheng This study used laboratory experiments to assess degradation of crude oil by physical and biological processes including dissolution and consumption. To perform this study, we have developed a bioassay that consists of a flow chamber with a bottom glass substrate printed with an array of pico-liter oil droplets using micro-Transfer Printing. The technique allows the printing of highly homogeneous pico-liter droplet array with different dimensions and shapes that can be maintained for weeks. Since the droplets are pinned and stationary on the bottom substrate, the key processes can be evaluated by measuring the change of shape and volume using Atomic Force Microscopy. Parallel microfluidic bioassays are established at the beginning, exposed to abiotic/biotic solutions, and scarified for characterization at given time intervals for each experiment. Two processes, dissolution and consumption, are investigated. In addition, the effects of dispersant on these processes are also studied. The results show that the amount of oil degraded by bacteria accounts for almost 50{\%} of the total volume in comparison to 25{\%} via dissolution. Although dispersant has a subtle effect on dissolution, the effect on rates of consumption and its asymptotic behavior are substantial. Experiments involving different bacterial strains, dispersant concentration, and flow shear rate are on-going. [Preview Abstract] |
Tuesday, November 22, 2016 3:01PM - 3:14PM |
R15.00008: Biodegradation of crude oil dispersions by marine bacteria Gabriel Juarez, Vicente Fernandez, Roman Stocker Dispersants are used to break up marine oil slicks and increase the available surface area for bacteria to degrade oil hydrocarbons. However, this common view neglects key elements of the microscale interactions between bacteria and oil droplets, namely encounters and growth.~Utilizing experimental observations of bacteria colonizing oil droplets, we model the interactions affecting hydrocarbon consumption between a collection of oil droplets with varying sizes and a single bacterial pool.~The results show that degradation time is minimized for intermediate droplet sizes and that reducing droplet size too much can lead to years in increased degradation time. This mechanical model provides a baseline for understanding oil biodegradation and mitigation strategies in open marine systems. [Preview Abstract] |
Tuesday, November 22, 2016 3:14PM - 3:27PM |
R15.00009: Quantifying oil degradation processes by flow, microbes and dispersant using digital holographic interferometry and micro-bioassay jian Sheng, Maryam Jalali, Larry Brock The unceasing demand of hydrocarbons has led and will lead to the future events of releasing crude into marine environment like Deep Horizon oil spill. The burning question to scientific community after the spill was the fate of oil spill especially with high concentration of dispersant. It is found that various physical processes such as wind, wave, turbulence, compounded with dispersants, break oil into suspension of micro-droplets. It is widely accepted that dispersant reduces interfacial tension and results in increased surface to volume ratio and subsequently improve biodegradation. Due to complexity of oil composition, key mechanisms differ substantially from well-studied laboratory system, especially in the presence of other environmental factors such as flow shear and microbes. To investigate these mechanisms at oil water interface qualitatively, we have developed a micro-bioassay consisting of microfluidics with a substrate printed with oil droplet array and a digital holographic interferometer (DHI). The degradation of micro-droplets is evaluated with the change of shape and volume measured in real time by DHI at a 2-minute interval over 100 hours. Time resolved experiments are performed to study effects of droplet size, dispersant concentrations, flow shear, and different bacteria species on the rate of degradation. The details on the rate and mechanisms will be provided in the talk. [Preview Abstract] |
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