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 G29: Biological Fluid Dynamics : Animals |
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Chair: Jamey Jacob, Oklahoma State University Room: 611 |
Sunday, November 24, 2019 3:48PM - 4:01PM |
G29.00001: Examining the effects of hydrodynamic features on biofouling growth and suppression Lena Dubitsky, Mark Menesses, Jesse Belden, James Bird The growth of biofouling organisms such as algae, barnacles, and mussels on submerged surfaces is a ubiquitous phenomenon and generally undesirable. Heavy biofouling on ships leads to increased drag and subsequent fuel costs, and even small amounts of fouling can interfere with scientific instruments in the field. It is known that biofouling growth is a consequence of both biological and environmental conditions, with the latter including a variety of possible fluid mechanic phenomena. While various researchers have investigated select hydrodynamic effects, a comprehensive picture linking flow features to fouling development is elusive. Through field experiments and laboratory analysis, we examine the interactions between fluid flow structures, interfaces, and biofouling growth patterns. Such characterization has the potential to improve dynamic anti-fouling mechanisms. [Preview Abstract] |
Sunday, November 24, 2019 4:01PM - 4:14PM |
G29.00002: Chemical Interactions around Pulsing Soft Corals Matea Santiago, Laura Miller, Shilpa Khatri A subset of sessile Octocorals (Family Xenidaee) actively and almost constantly pulse their tentacles. Experimental results indicate that the pulsing facilitates the photosynthesis of the symbiotic algae that live on the Octocorals. It is hypothesized that a significant source of the corals’ energy is the byproduct of the photosynethsis by the symbiotes. We model the photosynthesis of the symbiotic algae as a gas exchange of carbon dioxide to oxygen, where the coral tentacles are modeled as a source and sink of chemical concentrations. Additionally, the fluid-structure interaction of the pulsing corals, modeled using the immersed boundary method, is coupled to these chemical concentrations. We will present numerical simulations with varying parameters which have been used to gain insight to the complex interactions between the pulse driven fluid flow and the surrounding chemical concentrations. [Preview Abstract] |
Sunday, November 24, 2019 4:14PM - 4:27PM |
G29.00003: Mixing and pumping functions in a zebrafish larval intestine Kenji Kikuchi, Hyeongtak Noh, Keiko Numayama-Tsuruta, Takuji Ishikawa Transportation phenomena in the gut are extremely important for digestive, metabolism and absorption in nutrient uptake. The function of mixing and pumping in the intestine, which is a relatively larger vessel in the tracts of the body, has been partially understood in the physiological and medical fields, but not been fully clarified in the physical and mechanical aspects. The flow in the intestine has been recently focused on a distribution of gut flora concerning inflammably bowel disease, diabetes, and cancer. Even though quasi-static distribution analysis of the gut flora has been developed using a next-generation sequencer for medical diagnostics, but mechanical reasons for medical and surgical therapies have not been approached due to invisibility in the body. Here, we proposed \textit{in vivo} real-time intestinal flow measurement in the larval zebrafish intestine, which has justified similar constriction anatomically and genetically, using a fluorescent particle tracking velocimetry for analysis of mixing and pumping functions of the posterior and interior intestines. Péclet number in the intestines led us to our mechanical understanding; the mixing and pumping functions were crossing over after meal in the zebrafish larva. [Preview Abstract] |
Sunday, November 24, 2019 4:27PM - 4:40PM |
G29.00004: Pump Function of C. elegans Pharynx in Highly Viscous Environments Yuki Suzuki, Kenji Kikuchi, Keiko Numayama-Tsuruta, Takuji Ishikawa A nematode C. elegans is a filter feeder, which lives in various viscous habitats such as soil and rooting fruits. C. elegans draws a suspension of food bacteria and separates them from the solvent water by using the pharyngeal pump. Former studies have proposed the mechanism of the food condensation only in low viscosity environments. Although C. elegans lives mostly in highly viscous habitats, few studies have investigated the food condensation in highly viscous conditions. Hence, it is not clear how C. elegans can eat bacteria to survive in highly viscous environments. In this study, we investigated the effect of viscosity on the survival of worms and the pump function of the pharynx in highly viscous conditions. We found that the survival rate of worms diminished with increase in viscosity. We also found that the pump function weakened due to higher viscosity while the pump power rose with increase in viscosity. This result suggests that the amount of ingested food declined with increase in viscosity since the pharyngeal pump could expand and contract inadequately in high viscosity. Finally, our results indicate that decrease in the survival rate of worms would be related with decline in the amount of food ingested by the pharyngeal pump in high viscosity. [Preview Abstract] |
Sunday, November 24, 2019 4:40PM - 4:53PM |
G29.00005: Snail feeding at the air-water interface Daisuke Takagi, Soyoun Joo, Robert Cowie, Sungyon Lee, Sunghwan Jung Apple snails exhibit an intriguing feeding behavior at the air-water interface: they deform the foot to set up a funnel-like structure with surface waves traveling radially inwards. We report quantitative measurements of the resultant flow generated on and around the snails. Our observations reveal that distant food particles floating on the interface are effectively drawn in and collected at the center of the funnel. We develop a mathematical model based on lubrication theory to explore plausible physical mechanisms driving the entire system. The snails’ efficient feeding strategy offers a great source of inspiration for engineering devices designed to drive and control particles along any interface. [Preview Abstract] |
Sunday, November 24, 2019 4:53PM - 5:06PM |
G29.00006: Characterization of Cetacean Blowhole Flow Fields from In Situ Measurements Alvin Ngo, Mitchell Ford, Chris Barton, Richard Gaeta, Aaron Alexander, Arvind Santhanakrishnan, Jamey Jacob The stress levels of Atlantic bottlenose dolphins can be quantified through hormone concentrations in mucus samples expelled from the blowhole during regular breathing. Though easily monitored in dolphins under human care, collecting viable mucus samples from wild dolphins is challenging. In order to obtain samples from wild dolphins, a better understanding of the flow characteristics of the jet expelled from a dolphin's blowhole is required. The multi-phase properties of the flow in conjunction with the evasiveness of the dolphins present a significant issue. Analysis of the flow expelled from the blowhole of a dolphin under human care was performed using high speed (4500 frames per second) imaging, and Particle Image Velocimetry was used to generate velocity vector fields. Maximum fluid velocities exiting the blowhole were estimated to be between 22.5 and 27.5 m/s across the three different subjects of varying age and size. A momentum flux analysis was performed to estimate volumetric flow rate and breath intake/outtake characteristics. Characterization of the flow field sets the foundation for the design and development of a dolphin blowhole simulator for sample attainment testing. [Preview Abstract] |
Sunday, November 24, 2019 5:06PM - 5:19PM |
G29.00007: Development of a Simulator to Mimic a Dolphin Blowhole Jet Flow Field Chris Barton, Richard Gaeta, Alvin Ngo, Mitchell Ford, Arvind Santhanakrishnan, Aaron Alexander, Jamey Jacob The health of bottlenose dolphins can be monitored by marine biologists through an analysis of their mucus contained in their breath. To capture a dolphin's breath in the wild, an Unmanned Aerial Systems (UAS) can fly ``through'' the breath when expelled thus the extent of the exhaled breath is required to properly design the UAS platform. This jet is impulsive, unsteady, two-phase, and in cross flow. A mechanical device has been designed and fabricated to simulate this type of jet for use in wind tunnels and ultimately for UAS aircraft trials. Requirements for this simulator were obtained using three separate dolphins under human care of varying age, weight, and gender by taking high-speed videos of the dolphin's breath in two planes. PIV measurements were calculated from the videos and used to guide the development of the specialized jet simulator. In addition, existing mass flow data from measurements of dolphins show that these breaths vary from 20-140 liters per second in a time duration of 0.26-0.31 seconds. These requirements were used to design the biologically inspired two-phase jet. Flow measurements of the blow-hole jet dynamics are compared with in-situ field data of actual dolphins. [Preview Abstract] |
Sunday, November 24, 2019 5:19PM - 5:32PM |
G29.00008: Two-Phase Computational Fluid Dynamics Simulations of Dolphin Blowhole Expulsion Jets Aaron Alexander, Richard Gaeta, Ngo Alvin, Mitchell Ford, Jason Bruck, Haley O’Brien Monitoring the well-being of the wild dolphin population poses a challenge for biologists. While dolphins in human care can be trained to provide biological samples for monitoring, other methods must be utilized to obtain samples from wild dolphins. It is known that the mucus found in the flow generated from dolphins’ blowholes can be tested for hormones that help understand the current health status of the dolphin. Yet, the emitted jets from dolphin blowholes have not been well characterized. In order to understand these jets so that adequate samples may be obtained by Unmanned Aerial Systems (UAS) without spooking the dolphins, a combined program of in-situ measurements, experimental setups, and computational simulations has been designed. This study comprises the computational simulation leg of the effort and uses high fidelity scans of a dolphin respiratory system to create a computational fluid dynamic (CFD) replication of the jet emitted from the blowhole. A two-phase flow model resolves the entrainment of the mucus in the expelled jet. Additionally, a cross-wind is implemented to model the effect of the head-wind generated by the forward swimming of the dolphin. [Preview Abstract] |
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