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 L20: Bio: General Topics I |
Hide Abstracts |
Chair: Daniel Anderson, George Mason University Room: D137-138 |
Monday, November 21, 2016 4:30PM - 4:43PM |
L20.00001: A Reduced-dimension Model of Liquid Plug Propagation in Tubes David Halpern, Hideki Fujioka, Jason Ryans, Donald Gaver We developed a reduced dimensional model of the flow resistance by the motion of a viscous plug through a liquid lined tube. This is motivated by our interest in developing large-scale models of interfacial flows in pulmonary networks. Unfortunately, full CFD calculations are not viable, so we propose a semi-empirical formula for the resistance as a function of plug length, capillary number (Ca) and precursor film thickness. We developed CFD-based empirical relationships for the resistance contributors (front and rear meniscus and the plug core). The front meniscus resistance varies with Ca and the precursor film thickness. The rear meniscus resistance increases monotonically with decreasing Ca. We use a Poiseuille model in the core region, so the resistance linearly increases with plug length. With this we estimate the max wall shear and normal stress and gradients. The results show that for fingers of air propagating through airways, the epithelial cell damage correlates with the pressure gradient. However, for shorter plugs the front meniscus may provide substantial stresses that could modulate this behavior and may influence cell injury. [Preview Abstract] |
Monday, November 21, 2016 4:43PM - 4:56PM |
L20.00002: Modeling glycocalyx of the tear film as poroelastic layer Javed Siddique, Antonio Mastroberardino, Richard Braun, Daniel Anderson In this study we investigate a one-dimensional model for the evolution of the tear film subject to locally elevated evaporation at its anterior surface. We formulate a thin film model based on a combination of lubrication theory and mixture theory in order to understand the dynamics between the aqueous layer and the glycocalyx, which we treat as a poroelastic region. The model includes the physical effects of evaporation, surface tension, and viscosity. [Preview Abstract] |
Monday, November 21, 2016 4:56PM - 5:09PM |
L20.00003: Contact lens and tear film dynamics during blinking Timothy Reid, Daniel Anderson We develop a mathematical model that couples the dynamics of the tear film and contact lens during blinking. We derive an ordinary differential equation for the motion of the contact lens (parallel to the cornea) driven and retarded by viscous forces in the thin fluid films separating the contact lens from the eyelids and the corneal surface. Using the contact lens motion and tear film dynamics models we calculate a numerical solution of tear film thickness, showing that the lens and lid motion influence the tear film dynamics. The numerical solution uses a mapped Chebyshev spectral method for the spatial derivatives to reduce the model to a system of differential algebraic equations. [Preview Abstract] |
Monday, November 21, 2016 5:09PM - 5:22PM |
L20.00004: Simulation Of The Synovial Fluid In A Deformable Cavity Nancy Martinez-Gutierrez, Laura A. Ibarra-Bracamontes The main components of a synovial joint are a cartilage and a biofluid known as the synovial fluid. The results were obtained using the FLUENT software to simulate the behavior of the synovial fluid within a deformable cavity with a simple geometry. The cartilage is represented as a porous region. By reducing the available region for the fluid, a fluid displacement into the cartilage is induced. The total pressure reached in the interface of the deformable cavity and the porous region is presented. The geometry and properties of the system are scaled to values found in a knee joint. The effect of deformation rate, fluid viscosity and properties of the porous medium on the total pressure reached are analyzed. The higher pressures are reached either for high deformation rate or when the fluid viscosity increases. [Preview Abstract] |
Monday, November 21, 2016 5:22PM - 5:35PM |
L20.00005: The circulation of the cerebrospinal fluid (CSF) in the spinal canal Antonio L Sanchez, Carlos Martinez-Bazan, Juan C Lasheras Cerebrospinal Fluid (CSF) is secreted in the choroid plexus in the lateral sinuses of the brain and fills the subarachnoid space bathing the external surfaces of the brain and the spinal canal. Absence of CSF circulation has been shown to impede its physiological function that includes, among others, supplying nutrients to neuronal and glial cells and removing the waste products of cellular metabolism. Radionuclide scanning images published by Di Chiro in 1964 showed upward migration of particle tracers from the lumbar region of the spinal canal, thereby suggesting the presence of an active bulk circulation responsible for bringing fresh CSF into the spinal canal and returning a portion of it to the cranial vault. However, the existence of this slow moving bulk circulation in the spinal canal has been a subject of dispute for the last 50 years. To date, there has been no physical explanation for the mechanism responsible for the establishment of such a bulk motion. We present a perturbation analysis of the flow in an idealized model of the spinal canal and show how steady streaming could be responsible for the establishment of such a circulation. The results of this analysis are compared to flow measurements conducted on in-vitro models of the spinal canal of adult humans. [Preview Abstract] |
Monday, November 21, 2016 5:35PM - 5:48PM |
L20.00006: Filling a Conical Cavity Kyle Nye, Azar Eslam-Panah Root canal treatment involves the removal of infected tissue inside the tooth's canal system and filling the space with a dense sealing agent to prevent further infection. A good root canal treatment happens when the canals are filled homogeneously and tightly down to the root apex. Such a tooth is able to provide valuable service for an entire lifetime. However, there are some examples of poorly performed root canals where the anterior and posterior routes are not filled completely. Small packets of air can be trapped in narrow access cavities when restoring with resin composites. Such teeth can cause trouble even after many years and lead the conditions like acute bone infection or abscesses. In this study, the filling of dead-end conical cavities with various liquids is reported. The first case studies included conical cavity models with different angles and lengths to visualize the filling process. In this investigation, the rate and completeness at which a variety of liquids fill the cavity were observed to find ideal conditions for the process. Then, a 3D printed model of the scaled representation of a molar with prepared post spaces was used to simulate the root canal treatment. The results of this study can be used to gain a better understanding of the restoration for endodontically treated teeth. [Preview Abstract] |
Monday, November 21, 2016 5:48PM - 6:01PM |
L20.00007: Calculation of pressure drop in the developmental stages of the medaka fish heart and microvasculature sreyashi chakraborty, Pavlos Vlachos Peristaltic contraction of the developing medaka fish heart produces temporally and spatially varying pressure drop across the atrioventricular (AV) canal. Blood flowing through the tail vessels experience a slug flow across the developmental stages. We have performed a series of live imaging experiments over 14 days post fertilization (dpf) of the medaka fish egg and cross-correlated the red blood cell (RBC) pattern intensities to obtain the two-dimensional velocity fields. Subsequently we have calculated the pressure field by integrating the pressure gradient in the momentum equation. Our calculations show that the pressure drop across the AV canal increases from 0.8mm Hg during 3dpf to 2.8 mm Hg during 14dpf. We have calculated the time-varying wall shear stress for the blood vessels by assuming a spatially constant velocity magnitude in each vessel. The calculated wall shear stress matches the wall shear stress sensed by human endothelial cells (10-12 dyne/sq. cm). The pressure drop per unit length of the vessel is obtained by doing a control volume analysis of flow in the caudal arteries and veins. The current results can be extended to investigate the effect of the fluid dynamic parameters on the vascular and cardiac morphogenesis. [Preview Abstract] |
Monday, November 21, 2016 6:01PM - 6:14PM |
L20.00008: Vascular wall shear stress in zebrafish model of early atherosclerosis Woorak Choi, Eunseok Seo, Eunseop Yeom, Sang Joon Lee Although atherosclerosis is a multifactorial disease, the role of hemodynamic force has strong influence on the outbreak of the disease. Low and oscillating wall shear stress (WSS) is associated with the incidence of atherosclerosis. Many researchers have investigated relationships between WSS and the occurrence of atherosclerosis using \textit{in vitro }and \textit{in vivo} models. However, these models possess technological limitations in mimicking real biophysiological conditions and monitoring the temporal progression of atherosclerosis. In this study, a hypercholesterolaemic zebrafish model was established as a novel model to resolve these technical limitations. WSS in blood vessels of 15 days post-fertilisation zebrafish was measured using a micro PIV technique, and the spatial distribution of lipids inside blood vessels was quantitatively visualized using a confocal microscopy. As a result, lipids are mainly deposited in the regions of low WSS. The oscillating WSS is not induced by blood flows in the zebrafish disease model. The present hypercholesterolaemic zebrafish model would be useful for understanding the effect of WSS on the early stage of atherosclerosis. [Preview Abstract] |
Monday, November 21, 2016 6:14PM - 6:27PM |
L20.00009: What optimization principle explains the zebrafish vasculature? Shyr-Shea Chang, Kyung In Baek, Tzung Hsiai, Marcus Roper Many multicellular organisms depend on biological transport networks; from the veins of leaves to the animal circulatory system, to redistribute nutrients internally. Since natural selection rewards efficiency, those networks are thought to minimize the cost of maintaining the flow inside. But optimizing these costs creates tradeoffs with other functions, e.g. mixing or uniform distribution of nutrients. We develop an extended Lagrange multiplier approach that allows the optimization of general network functionals. We also follow the real zebrafish vasculature and blood flows during organism development. Taken together, our work shows that the challenge of uniform oxygen perfusion, and not transport efficiency, explain zebrafish vascular organization. [Preview Abstract] |
Monday, November 21, 2016 6:27PM - 6:40PM |
L20.00010: Time-resolved transglottal pressure measurements in a scaled up vocal fold model Hunter Ringenberg, Michael Krane, Dylan Rogers, Mitchel Misfeldt, Timothy Wei Experimental measurements of flow through a scaled up dynamic human vocal fold model are presented. The simplified 10x scale vocal fold model from Krane, \textit{et al}. (2007) was used to examine fundamental features of vocal fold oscillatory motion. Of particular interest was the temporal variation of transglottal pressure multiplied by the volume flow rate through the glottis throughout an oscillation cycle. Experiments were dynamically scaled to examine a range of frequencies, 100 -- 200 Hz, corresponding to the male and female voice. By using water as the working fluid, very high resolution, both spatial and temporal resolution, was achieved. Time resolved movies of flow through symmetrically oscillating vocal folds will be presented. Both individual realizations as well as phase-averaged data will be shown. Key features, such as randomness and development time of the Coanda effect, vortex shedding, and volume flow rate data have been presented in previous APS-DFD meetings. This talk will focus more on the relation between the flow and aeroacoustics associated with vocal fold oscillations. [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. |
© 2025 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