Bulletin of the American Physical Society
75th Annual Meeting of the Division of Fluid Dynamics
Volume 67, Number 19
Sunday–Tuesday, November 20–22, 2022; Indiana Convention Center, Indianapolis, Indiana.
Session J05: Biological Fluid Dynamics: General I |
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Chair: Omid Amili, University of Toledo Room: 132 |
Sunday, November 20, 2022 4:35PM - 4:48PM Author not Attending |
J05.00001: The viscoelastic spit of termite soldiers Elio J Challita, Prateek Sehgal, Saad Bhamla
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Sunday, November 20, 2022 4:48PM - 5:01PM |
J05.00002: Simulations of Pulsing Soft Corals Sarah E Downs, Matea Santiago, Roummel Marcia, Kevin A Mitchell, Gabrielle M Hobson, Laura A Miller, Shilpa Khatri Sessile soft corals in the Xeniidae family actively pulse their tentacles and are one of the few known species to move in such an energetically expensive way for a purpose other than locomotion. This pulsing was first thought to facilitate food capture, however they are rarely found with food in their gastric cavity. Instead experimental work has hypothesized that the pulsing mixes the surrounding fluid to increase the rate of photosynthesis, by up to an order of magnitude, for their symbiotic algae that provide the corals with energy. The pulsing of the corals and resulting fluid flow are modeled in three dimensions using the immersed boundary method and by solving the Navier-Stokes equations for the incompressible flow velocity and pressure, using the open-source software IBFE. Using two-dimensional slices of simulated velocity fields, we seek to understand how the coral motion affects the fluid mixing. Preliminary results will be presented. |
Sunday, November 20, 2022 5:01PM - 5:14PM |
J05.00003: On the role of the ventilatory wave in dragonfly larvae Liad Elmelech Aquatic dragonfly larvae have various methods of ventilation in their modified hindgut chamber. One of these ventilations is chewing ventilation, which is a wavelike motion of the chamber wall. While this mode has been reported by multiple studies, its role remains unclear. In this study, we correlate the chamber wall motion with the internal and external flow to understand the role of the anteriorly propagating chamber wave in the larvae of Libellula sp. The transparency of the species allowed optical access to the internal flow and chamber kinematics. The particulates in the pond water visualized the flow inside the breathing chamber. We observed that soon after the wave motion ends, particles deep within the hindgut rapidly accelerates. This suggests that the function of the anteriorly propagating wave might be to pressurize the back end of the chamber in order to create pressure gradient within. In conjunction with the transmural pressure generated by compression of the abdomen, the axial pressure gradient deep within the chamber might assist in cleaning particulates lodged deep within the breathing chamber. |
Sunday, November 20, 2022 5:14PM - 5:27PM |
J05.00004: Fluid Mediated Unraveling of Thread Skeins Mohammad Tanver Hossain, Wonsik Eom, Dakota Piorkowski, Douglas Fudge, Sameh H Tawfick, Randy H Ewoldt Hagfish slime unravels within a fraction of a second to thwart a predator attack. Understanding the unraveling mechanism will create a pathway to produce synthetic thread skein analogs that uncoil to reveal a 1:1000 length expansion ratio. Here we report the scaling relations that relate hagfish thread properties (elasticity, diameter, length) to the hydrodynamic flows required for unraveling, which are stated in terms of relative flow velocities or strain rates and fluid viscosity. Modeling considered viscous hydrodynamic force can be responsible for rapid unraveling and is extended to include flow effects for larger length scale fibers where inertial effects of the fluid or fiber are considered (high Reynolds number regime). Our modeling shows that a minimum of 17s-1 shear rate is required for natural skeins to unravel within 400ms. The collapse time of a single extended elastic thread was also considered, which is set by the ratio of fluid viscosity to the thread elasticity times a geometric factor. This modeling was then extended to consider a network of elastic elements via a poroelasticity model to obtain the collapse timescale of a slime network after deployment. Based on our findings, we provide a design criterion for synthetic skeins and the fluid viscosity and flow conditions required to unravel them. Experimental flow visualization of unraveling is pursued with a counter-rotating Couette flow setup in a rotational rheometer (MCR 702) with a single natural hagfish skein to support the hypothesis of viscous drag-dominated unraveling. |
Sunday, November 20, 2022 5:27PM - 5:40PM |
J05.00005: The Flapping Frequency of Dust Bathing in Birds Po-Lin Kuo, Patricia J Yang Birds remove excess lipids and ectoparasites from the plumage by dust bathing. During dust bathing, birds scratch their legs to get loose sand particles onto their bodies and flap their wings to shake them off in seconds, but this mechanism is poorly understood. In this study, we collect thirty videos on dust bathing in birds with masses across four orders of magnitude. The flapping frequency is in the range of 1 to 10 Hz. Among these birds, land fowl such as chickens and ostriches have the flapping frequency decreasing with body mass ranging from 0.1 to 88 kg. We hypothesize that larger land fowl have a slower flapping frequency because of a limited wingspan during dust bathing. This study may shed light on the bioinspired dry cleaning technologies such as oil-resist mechanisms in sensors and cameras. |
Sunday, November 20, 2022 5:40PM - 5:53PM |
J05.00006: Flow through an array of rigid hairs JP P Raimondi, Sri Savya Tanikella, Emilie Dressaire Hair-covered surfaces serve a variety of purposes in Nature, from chemical sensing on the antennules of a crustacean to flow generation in our respiratory system. Confining structures, walls or larger hairs, are believed to focus the flow on the hair-covered region. We investigate the influence of the confinement on the flow through an array of passive hairs. Previous work has shown that the flow exhibits three regimes: rake, deflection, and sieve. The regimes describe the relative amount of fluid traveling through and around the finite array of hairs, and depend on the Reynolds number and the porosity of the array. To explore the effects of confinement experimentally, we vary the hair spacing, channel dimension and flow rate. We measure the velocity field using Particle Image Velocimetry. We also conduct numerical simulations for a wider sweep of the parameters. Our experimental results agree well with results of finite element simulations and reveal that the confinement of an array of hairs can shift the Reynold’s number at which the flow regimes are observed and limit which regimes can occur. These results should provide insight into the morphology of hairy surfaces and have implications in the design of bio-inspired flow sensors and filters. |
Sunday, November 20, 2022 5:53PM - 6:06PM |
J05.00007: Phytoplankton morphology affects susceptibility to aggregation via microscale turbulence Melissa Ruszczyk, Maria Cardelino, Gianna Perretta, Dorsa Elmi, Donald R Webster Phytoplankton are subject to microscale turbulence which drives aggregation creating phytoplankton blooms. If the aggregated species produce toxins, blooms may become detrimental, resulting in harmful algae blooms. To understand how morphology affects aggregation, disk-shaped Coscinodiscus wailesii (50-100μm pervalar axis, 100-200μm diameter) and rod-shaped Stephanopyxis sp. (20-100μm length, 40-60μm diameter) were exposed to four intensity levels of a Burgers vortex mimicking a dissipation-scale turbulent eddy. With this approach, particle-flow interaction is essentially deconstructed to examine the dynamics around a dissipation-scale eddy. Three-dimensional trajectories are compared to trajectories of a neutrally-buoyant, spherical particle (Orgasol; 50μm diameter) across vortex intensity levels. Preliminary results reveal that C. wailesii has similar motion to Orgasol, while Stephanopyxis sp. decreases net to gross displacement ratio and trajectory-flow alignment with increasing turbulence level to a greater extent than both C. wailesii and Orgasol, suggesting that its longer chain-shape influences how it interacts with a dissipation-scale eddy and, ultimately, microscale turbulence. |
Sunday, November 20, 2022 6:06PM - 6:19PM |
J05.00008: Fluid Dynamics of Chemical Scent Detection in Stingrays Kelsi M Rutledge, Christin T Murphy, Malcolm S Gordon, John O Dabiri Stingrays are macrosmatic, relying on their sense of smell as one of their primary senses for survival. Olfaction is crucial for predator and prey recognition, navigation and tracking, and reproductive signaling. While these fishes rely on water flow to direct odors into their nose, there have been very few studies on the fluid dynamics of their olfaction. With an odor-impeding boundary layer and no direct pump-like system, how do these fishes efficiently capture chemical stimuli? To understand how nasal morphology influences chemical detection, models of the 4 nasal morphotypes seen in batoids were 3D printed in clear resin from CT scans. Models were mounted in a water tunnel and dye visualization and particle image velocimetry methods were performed at various Reynolds numbers. Models were printed with their mouths opened and tubing connecting to a syringe pump to mimic respiration. To determine how respiration indirectly influences nasal irrigation, models were tested with a continuous “inhale” respiratory rate. The pitch of the head was investigated at 0 and 8°, to mimic the change in body orientation with increased swimming speed. Particle image velocimetry was used to measure the flow. We found that different nasal geometries produce different patterns of flow and odor capture mechanisms. Pitch and respiratory processes are also crucial parameters for odor detection. This study lends insights into the fluid dynamics of chemical sensing in the marine environment and highlights the importance of the morphology of the system for odor capture and circulation. |
Sunday, November 20, 2022 6:19PM - 6:32PM |
J05.00009: Muscle-driven movement of fully elastic pulsing corals Matea Santiago, Alexander Hoover, Shilpa Khatri, Laura A Miller Corals in the Xeniidae family are sessile organisms that actively pulse their tentacles. The pulsing behavior is unusual since it is not for locomotive purposes. Using computational fluid dynamics, we seek to understand this behavior and the resulting flow. Previous work has made modeling simplifications, including modeling the coral in two dimensions, assuming the tentacle as infinitely thin, and prescribing the tentacle motion. In this work, the immersed boundary finite element method (IBFE), a part of the open-source software IBAMR is used to model a fully three-dimensional coral. Active tension will be applied to the tentacles as a simplified muscle model rather than a prescribed motion. This approach could allow for observing emergent properties of the interaction between the coral motion and fluid flow that would not be present with prescribed motion. Preliminary work will be presented. |
Sunday, November 20, 2022 6:32PM - 6:45PM |
J05.00010: An Integrability Technique for Fluid Flow Induced Deformation of a Boundary Hair Jonas Smucker, Zerrin Vural, José Alvarado, Philip J Morrison The deformation of a dense carpet of hair due to Stokes flow in a channel can be described by a nonlinear integro-differential equation for the shape of a single hair, which possesses several solutions for a given choice of parameters. While being posed in a previous study and bearing resemblance to the pendulum problem from mechanics, this equation has not been analytically solved until now. Despite the presence on an integral with a nonlinear functional dependence on the dependent variable, the system is integrable. We compare the analytically obtained solution to a finite-difference numerical approach, identify the physically realizable solution branch, and briefly study the solution structure through a conserved energy-like quantity. Time-dependent fluid-structure interactions are a rich and complex subject to investigate and we argue that the solution discussed herein can be used as a basis for understanding these systems. |
Sunday, November 20, 2022 6:45PM - 6:58PM |
J05.00011: Understanding the Flow-signal correlation in seal whisker array sensing using a supervised deep learning model Dariush Bodaghi, Geng Liu, Xudong Zheng, Qian Xue Phocid seals detect and track artificial or biogenic hydrodynamic trails based on mechanical signals of their whisker arrays. Behavior studies have shown that by using the collective array signals resulting from the interaction with the oncoming vortices, seals are able to locate and distinguish the upstream obstacles. In this study, we investigate the correlation of characteristics of upstream obstacles, flow structures and whisker array signals using a supervised deep learning neural network model. A circular plate is placed in front of a realistic harbor seal head to generate hydrodynamic wake structures; one-way FSI was then simulated to obtain the dynamic behavior and root mechanical signal of each whisker in the two whisker arrays on the seal head. The locations and orientations of the circular plate are systematically varied to generate a large training data set. The network takes the inputs of the temporal mechanical signals of the two arrays and is trained to predict the location and orientation of the plate. The primary features of array signals are identified by incorporating an autoencoder into the network model and are further related to the vortex structures to understand their correlations. This study would provide helpful insight into seal whisker flow sensing mechanisms. |
Sunday, November 20, 2022 6:58PM - 7:11PM |
J05.00012: Control of the localized bioconvection unit of Euglena suspension by manipulating light environment Hiroshi Yamashita, Touya Kamikubo, Kazuki Muku, Nobuhiko J Suematsu, Makoto Iima Collective motion of active matters within a confined region, i.e. bird flocking, has attracted attention not only in biology but also in fluid dynamics, and has therefore been investigated extensively. However, there have been few reports on flocking in bioconvection. The present study is focused on the collective motion of Euglena. |
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