Bulletin of the American Physical Society
68th Annual Meeting of the APS Division of Fluid Dynamics
Volume 60, Number 21
Sunday–Tuesday, November 22–24, 2015; Boston, Massachusetts
Session R37: Biofluids: Swimming Animals |
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Chair: Christophe Clanet, École Polytechnique Room: Sheraton Back Bay A |
Tuesday, November 24, 2015 12:50PM - 1:03PM |
R37.00001: Diving birds Christophe Clanet, lucien masson, Gareth McKinley, Robert Cohen Many seabirds (gannets, pelicans, gulls, albatrosses) dive into water at high speeds (25 m/s) in order to capture underwater preys. Diving depths of 20 body lengths are reported in the literature. This value is much larger than the one achieved by men, which is of the order of 5. We study this difference by comparing the impact of slender vs bluff bodies. We show that, contrary to bluff bodies, the penetration depth of slender bodies presents a maximum value for a specific impact velocity that we connect to the velocity of diving birds. [Preview Abstract] |
Tuesday, November 24, 2015 1:03PM - 1:16PM |
R37.00002: Calanoid Copepod Behavior in Thin Layer Shear Flows: Freshwater Versus Marine A.N. Skipper, D.R. Webster, J. Yen Marine copepods have been shown to behaviorally respond to vertical gradients of horizontal velocity and aggregate around thin layers. The current study addresses whether a freshwater copepod from an alpine lake demonstrates similar behavior response. \textit{Hesperodiaptomus shoshone} is often the greatest biomass in alpine lakes and is the dominant zooplankton predator within its environment. The hypothesis is that \textit{H. shoshone} responds to vertical gradients of horizontal velocity, which are associated with river outflows from alpine lakes, with fine-scale changes in swimming kinematics. The two calanoid copepods studied here, \textit{H. shoshone} (freshwater) and \textit{Calanus finmarchicus }(marine), are of similar size (2 -- 4 mm), have similar morphologies, and utilize cruising as their primary swimming mode. The two animals differ not only in environment, but also in diet; \textit{H. shoshone} is a carnivore, whereas \textit{C. finmarchicus }is an herbivore. A laminar, planar jet (Bickley) was used in the laboratory to simulate a free shear flow. Particle image velocimetry (PIV) quantified the flow field. The marine species changed its swimming behavior significantly (increased swimming speed and turning frequency) and spent more time in the layer (40{\%} vs. 70{\%}) from control to treatment. In contrast, the freshwater species exhibited very few changes in either swimming behavior or residence time. Swimming kinematics and residence time results were also similar between males and females. Unlike the marine copepod, the results suggest the environmental flow structure is unimportant to the freshwater species. [Preview Abstract] |
Tuesday, November 24, 2015 1:16PM - 1:29PM |
R37.00003: Larvacean kinematics: a biological model of flapping flexible foils Alexa Baumer, Kakani Katija, Megan C. Leftwich Larvaceans are marine organisms found throughout the world's oceans that create mucus houses to filter food (e.g., small plankton, detritus, and particulates) from adjacent waters. Estimates indicate that discarded mucus houses, which are eventually abandoned by larvaceans, are responsible for one\textunderscore third of the particulate transported to the bottom of Monterey Bay in Central California. Once houses are abandoned, larvaceans swim freely to another location before generating a new one. Here we conduct a study of an undescribed larvacean, Bathocordaeus sp., to examine their free\textunderscore swimming and in-house behaviors, and how changes in their body kinematics may alter fluid interactions. High\textunderscore definition videos captured by remotely operated vehicles (ROVs) in Monterey Bay (from 2003 to present) are analyzed to extract the kinematics of larvacean tail motion during these two distinct swimming behaviors. Using in-house Matlab algorithms, we reveal significant differences in stroke dynamics as traveling waves propagate along the larvacean tail. These kinematic differences may have important implications for swimming performance and fluid filtration rates through larvacean mucus houses. [Preview Abstract] |
Tuesday, November 24, 2015 1:29PM - 1:42PM |
R37.00004: ABSTRACT WITHDRAWN |
Tuesday, November 24, 2015 1:42PM - 1:55PM |
R37.00005: Mechanical and scaling considerations for efficient jellyfish swimming Alexander Hoover, Laura Miller, Boyce Griffith With a fossil record dating over half a billion years, jellyfish represent one of the earliest examples of how multicellular organisms first organized into moving systems. Lacking an agonist-antagonist muscle pairing, jellyfish swim via a process of elastic deformation and recoil. Jellyfish propulsion is generated via the coordinated contraction of its elastic bell by its coronal swimming muscles and a complementary re-expansion that is passively driven by stored elastic energy. Recent studies have found jellyfish to be one of the most efficient swimmers due to its low energy expenditure in their forward movement. Using an immersed boundary framework, we will further examine the efficiency of jellyfish swimming by incorporating material models that are informed by the musculature present in jellyfish into a model of the elastic jellyfish bell in three dimensions. The fully-coupled fluid structure interaction problem is solved using an adaptive and parallelized version of the immersed boundary method (IBAMR). This model is then used to explore how variability in the mechanical properties of the bell affect the work done by the bell as well as the cost of transport related to jellyfish locomotion. We then examine how the efficiency of this system is affected by the Reynolds number. [Preview Abstract] |
Tuesday, November 24, 2015 1:55PM - 2:08PM |
R37.00006: Flapping, wobbling, and zig-zagging: Tomographic PIV measurements of Antarctic sea butterfly ''flying'' underwater D. Adhikari, D.R. Webster, J. Yen A portable tomographic PIV technique was used to study the fluid dynamics and kinematics of sea butterflies in Antarctica. Antarctic pteropods (or sea butterflies), which are currently threatened by ocean acidification, swim in seawater with a pair of gelatinous parapodia (or ``wings'') via a unique propulsion mechanism. Both power and recovery strokes propel the organism (1.5 -- 5 mm in size) upward in a sawtooth-like trajectory with average speed of 14 -- 30 mm/s and pitch the shell forwards-and-backwards at 1.9 -- 3 Hz. The pitching motion effectively positions the parapodia such that they stroke downward during both the power and recovery strokes. Reynolds numbers defined for flapping, translating, and pitching (i.e. \textit{Re}$_{f}$, \textit{Re}$_{U}$, and \textit{Re}$_{\mathrm{\Omega }})$ characterize the motion of the pteropod. For \textit{Re}$_{f}$ \textless 50, the shell does not pitch and the pteropod swims abnormally. We present a detailed comparison of the volumetric fluid velocity fields induced by pteropods swimming upwards with \textit{Re}$_{f} =$ 80 and 180. The pteropod at the lower \textit{Re}$_{f}$ creates an attached shear flow along the parapodia and pushes fluid in a method analogous to a paddle. In contrast, at higher \textit{Re}$_{f}$, the flow along the parapodia separates and generates complex vortex structures. [Preview Abstract] |
Tuesday, November 24, 2015 2:08PM - 2:21PM |
R37.00007: Experimental investigation of crustacean swimming with variation of limb structures Hong Kuan Lai, Milad Samaee, Geoffrey Donnell, Arvind Santhanakrishnan, Robert Guy, Timothy Lewis Crustaceans such as crayfish and krill swim by rhythmically paddling a set of four to five limbs (known as swimmerets or pleopods) originating from their abdomen. The limb motion in these animals has been observed to follow tail-to-head metachronal wave pattern with an approximate quarter-period inter-limb phase difference. The goal of this study is to investigate the hydrodynamics of this swimming mechanism as a function of inter-limb phase difference, inclusion of hinges in the limbs, and Reynolds number (Re). 2D PIV measurements were conducted on a scaled robotic model of metachronal paddling, consisting of a rectangular tank fitted with stepper motors coupled to a four-bar linkage that actuated four paddles immersed in water-glycerin fluid medium. The inter-limb phase difference was varied from 0{\%} (synchronous paddling) through 50{\%} across Re range of O(10-1000). Two types of limb models were used, including a simple flat plate and a `split-paddle' structure with two flat plates connected halfway with hinges. The results of the study show that limb models with hinges generated increased horizontal (thrust-producing direction) fluid velocity compared to the simple flat plate paddles, suggesting that asymmetry between power and return strokes is important to augment thrust. [Preview Abstract] |
Tuesday, November 24, 2015 2:21PM - 2:34PM |
R37.00008: Bio-inspired robotic legs drive viscous recirculating flows Daisuke Takagi, Rintaro Hayashi Crustaceans actuate multiple legs in a well-coordinated sequence to generate suitable flow for feeding and swimming. Inspired by tiny crustacean larvae operating at low Reynolds number, we study a scaled-up model in which slender rods oscillate independently in a bath of glycerol. Experiments reveal qualitatively different flow patterns depending on the phase and orientation of actuated rods. The observations are analyzed in the framework of slender-body theory for Stokes flow. This study shows that simple oscillatory motion of multiple legs can produce complex recirculating flows, with potential applications for mixing and pumping. [Preview Abstract] |
Tuesday, November 24, 2015 2:34PM - 2:47PM |
R37.00009: Volumetric flow around a swimming lamprey Andrea M. Lehn, Sean P. Colin, John H. Costello, Megan C. Leftwich, Eric D. Tytell A primary experimental technique for studying fluid-structure interactions around swimming fish has been planar dimensional particle image velocimetry (PIV). Typically, two components of the velocity vector are measured in a plane, in the case of swimming studies, directly behind the animal. While useful, this approach provides little to no insight about fluid structure interactions above and below the fish. For fish with a small height relative to body length, such as the long and approximately cylindrical lamprey, 3D information is essential to characterize how these fish interact with their fluid environment. This study presents 3D flow structures along the body and in the wake of larval lamprey, $\textit Petromyzon$ $\textit marinus$, which are 10-15 cm long. Lamprey swim through a 1000 cm$^3$ field of view in a standard 10 gallon tank illuminated by a green laser. Data are collected using the three component velocimeter V3V system by TSI, Inc. and processed using Insight 4G software. This study expands on previous works that show two pairs of vortices each tail beat in the mid-plane of the lamprey wake. [Preview Abstract] |
Tuesday, November 24, 2015 2:47PM - 3:00PM |
R37.00010: Investigation of Thunniform Swimming Using Material Testing, Biomimetic Robotics and Particle Image Velocimetry Ruijie Zhu, Vishaal Saraiya, Jianzhong Zhu, Gregory Lewis, Hilary Bart-Smith Thunniform swimming is well recognized as an efficient method for high-speed long-distance underwater travelers such as tuna. Previous research has shown that tuna relies on contraction and relaxation of red muscle to generate angular motion of its large, crescent-shaped caudal fin through its peduncle. However, few researchers conduct deep investigation of material properties of tuna caudal fin and peduncle. This research project is composed of two parts, first of which is determining mechanical properties of components such as spine joints, tendons, fin rays and cartilage, from which the biomechanics of tuna tail can be better understood. The second part is building a robotic system mimicking a real tuna tail based on previously retrieved information, and testing the system inside a flow tank. With the help of PIV (Particle Image Velocimetry), fluid-structure interaction of the biomimetic fin is visualized and data such as swimming speed and power consumption are retrieved through the robotic system. The final outcome should explain how the material properties of tuna tail affect fluid dynamics of thunniform swimming. [Preview Abstract] |
Tuesday, November 24, 2015 3:00PM - 3:13PM |
R37.00011: Copepod Behavioral Response to Simulated Frontal Flows D.R. Webster, A.C. True, M.J. Weissburg, J. Yen, A. Genin When presented with a fine-scale upwelling or downwelling shear flow in a laboratory flume, two tropical copepods from the Red Sea, \textit{Acartia negligens} and \textit{Clausocalanus furcatus}, performed a set of behaviors that resulted in apparent depth-keeping and the potential for producing patchiness. Analyses of free-swimming trajectories revealed a behavioral threshold shear deformation rate value of 0.05 s$^{\mathrm{-1}}$ for both species. This threshold triggered statistically significant changes in path kinematics (i.e., relative swimming speed and turn frequency) in the shear layer versus out-of-layer. Gross path characteristics (i.e., net-to-gross displacement ratio, NGDR, and proportional vicinity time, PVT) were also significantly different in the shear layer treatments compared to controls. The vertical net-to-gross displacement ratio (VNGDR) was introduced here to explain a spectrum of depth-keeping behaviors. The mean value of VNGDR significantly increased in the shear layer treatments and, coupled with excited relative swimming speeds, suggested the potential to induce large vertical transport (at the 10 cm scale of the observation). However, histograms of VNGDR revealed a bimodality, which indicated a sizable portion of the population was also displaying depth-keeping behavior. Those copepod trajectories displaying large VNGDR predominately consisted of copepods swimming against the flow, thereby resisting vertical advection, which is another potential depth-keeping mechanism. [Preview Abstract] |
Tuesday, November 24, 2015 3:13PM - 3:26PM |
R37.00012: Hydrodynamic role of longitudinal ridges in a leatherback turtle swimming Kyeongtae Bang, Jooha Kim, Sang-im Lee, Haecheon Choi The leatherback sea turtle ({\it Dermochelys coriacea}), the fastest swimmer and the deepest diver among marine turtles, has five longitudinal ridges on its carapace. These ridges are the most remarkable morphological features distinguished from other marine turtles. To investigate the hydrodynamic role of these ridges in the leatherback turtle swimming, we model a carapace with and without ridges by using three dimensional surface data of a stuffed leatherback turtle in the National Science Museum, Korea. The experiment is conducted in a wind tunnel in the ranges of the real leatherback turtle’s Reynolds number (Re) and angle of attack ($\alpha$). The longitudinal ridges function differently according to the flow condition (i.e. Re and $\alpha$). At low Re and negative $\alpha$ that represent the swimming condition of hatchlings and juveniles, the ridges significantly decrease the drag by generating streamwise vortices and delaying the main separation. On the other hand, at high Re and positive $\alpha$ that represent the swimming condition of adults, the ridges suppress the laminar separation bubble near the front part by generating streamwise vortices and enhance the lift and lift-to-drag ratio. [Preview Abstract] |
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