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 J06: Low Reynolds Number Locomotion: Plankton |
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Chair: Margaret Byron, Penn State University Room: 133 |
Sunday, November 20, 2022 4:35PM - 4:48PM |
J06.00001: Hydrodynamic Efficiency of Robotically Controlled Aurelia aurita in a Vertical Water Treadmill Simon R Anuszczyk, John O Dabiri Energy consumption is a limiting factor for mission duration of existing ocean monitoring techniques. Jellyfish have the lowest cost of transport of all metazoans and live in a wide range of ocean temperature, salinity, pH, and depth, making them ideal candidates for ocean monitoring robots. Aurelia aurita jellyfish stimulated with microelectronic swim controllers could serve as ocean sensors combining the benefits of low energy use, regenerative capabilities of live tissue, and inexpensive electronics. Previous work has demonstrated enhanced jellyfish vertical swimming speeds of 2.8 times baseline speeds without swim controllers. Indirect measurements suggest that this enhanced swimming can be achieved without proportional increases in energy consumption. Here, we examine this question using direct measurements of the hydrodynamic efficiency of robotically controlled Aurelia aurita associated with enhanced swimming speeds. Using PIV, we measure the kinetic energy of water set in motion by the animals to determine hydrodynamic efficiency. We utilize a 3,600-gallon tank to create a vertical water treadmill. This work demonstrates a new technique to characterize swimming performance in untethered aquatic species and connect wake measurements to swimming performance. |
Sunday, November 20, 2022 4:48PM - 5:01PM |
J06.00002: Automated laboratory for the study of biologically inspired soft settling bodies Matthew D Biviano, Kaare Hartvig Jensen Soft living organisms suspended, flying, or swimming in a fluid vary in size over nine orders of magnitude, from tens of nanometres to tens of meters. Understanding the evolution and behavior of these strikingly diverse organisms requires detailed knowledge of the interactions between their flexible bodies and the fluid medium. The emerging availability of advanced methods, such as 3D printing and laser cutting of soft materials, has enabled substantial progress in the field. Currently, however, steps forward are limited by the poor scalability of these methods and the cost of alternatives such as direct numerical simulations. We explore potential strategies and trade-offs for automated experiments based on said techniques. Implications for the evolutionary link between physical traits (e.g., terminal settling velocity) and organism shape are discussed. |
Sunday, November 20, 2022 5:01PM - 5:14PM Author not Attending |
J06.00003: Exploring Turning in Biohybrid Jellyfish Malaika Cordeiro, John O Dabiri Recent work has explored the use of robotically controlled jellyfish for ocean exploration. To date, those studies have focused on unidirectional locomotion. Here we explore the biomechanics and fluid dynamics relating to turning in these biohybrid robots. To characterize the relationship between robotic control inputs and the subsequent turning dynamics, we test a centrally embedded microelectronic control system with a series of electrode configurations varying in spatial location and relative stimulation timing. Fluorescent tags are inserted into jellyfish tissue and tracked in videos. The kinematic measurements drawn from video processing software enable further measurements of contraction wave speeds in the animal body, informing the determination of control laws to eventually steer the organisms along desired trajectories. These findings can facilitate the development of biohybrid jellyfish that incorporate directed 3D locomotion. |
Sunday, November 20, 2022 5:14PM - 5:27PM |
J06.00004: Locomotion at intermediate Reynolds numbers: particle shadow velocimetry measurements of ctenophore swimming across species Mohammadreza Zharfa, Adrian Herrera-Amaya, Margaret L Byron Ctenophores (comb jellies) are the largest animals that employ cilia for locomotion. They use millimeter-scale appendages (ctenes) composed of bundled cilia, which create flow by beating metachronally in rows. Past work has provided considerable understanding of ciliary flows at the micron scale (low Reynolds numbers), but less is known about how cilia operate at intermediate Reynolds numbers. We use ctenophores as a model to investigate these intermediate-scale ciliary flows. Conventional particle image velocimetry (PIV) methods are impractical at scales around a few millimeters, as the light sheet becomes nontrivially thick compared to the field of view; additionally, flows near surfaces can be difficult to resolve due to reflections. Particle shadow velocimetry (PSV), conversely, uses a narrow focal depth in lieu of a laser sheet and can measure smaller fields of view containing complex moving boundaries. We use PSV to investigate flows generated by several species of ctenophores which have different swimming and feeding strategies. We observe differences in ctene beating frequency and consequently oscillatory Reynolds number (ranging from 15 to 75) across species. We also analyze differences and similarities between the planar velocity fields measured for each species |
Sunday, November 20, 2022 5:27PM - 5:40PM |
J06.00005: Feeding of sessile ciliates in uniform and nonuniform nutrient concentrations Jingyi Liu, Yi Man, Eva Kanso Aquatic eukaryotic microorganisms use strategies such as swimming, sinking, or generating flow currents to increase their feeding rate. While many studies analyze nutrient uptake of swimming and sinking cells, less is known about how well sessile cells can compete in feeding compared to motile cells. Based on Blake's envelope model, we represent a sessile ciliated cell by a fixed sphere with a slip surface velocity representing the ciliary motion. We solve analytically for the cilia-generated flow field, then investigate the advection-diffusion behavior of a concentration of surrounding nutrients via numerical and asymptotic analysis. Starting from uniform background concentration of nutrients, we find that sessile ciliated cells can outperform, in terms of nutrient uptake, cells that use buoyancy-driven sinking, but they are no match to cells that use the same ciliary activity for self-propulsion. Importantly, we show that, in non-uniform background concentration, sessile ciliates can enhance their feeding to transcend the limitation they face in uniform concentration by generating flow currents from regions of higher concentration towards the cell. |
Sunday, November 20, 2022 5:40PM - 5:53PM |
J06.00006: Diverse swimming behaviors of Cryptophytes Ludivine D Sanchez Arias, Matthew D Johnson, Houshuo Jiang, Henry C Fu Cryptophytes are aquatic unicellular eukaryotes, or protists, that inhabit both marine and freshwater environments worldwide and whose photosynthetic forms may be important primary producers and prey for higher trophic levels. Cryptophytes have flattened, elliptical cells and swim using two flagella. Swimming in protists is one of their more conspicuous attributes that stimulated early studies on their ecology and taxonomy. In this research work, we investigate the swimming patterns and behaviors of a representative group of cryptophytes having different cell geometries, feeding behaviors, and plastid type and/or presence. We observe swimming cryptophytes using the High-Speed Microscale Imaging System, which allows behavioral evaluations in environments closer to natural conditions, avoiding confinement and heating effects common in traditional microscopy techniques. We have observed various swimming behaviors and speed among the species: helical trajectories with vastly different radii for Rhodomonas salina, Proteomonas sulcata, Chroomonas mesostigmatica, Chilomonas paramecium, Hemiselmis cryptochromatica and Guillardia theta; almost straight paths for Teleaulax amphioxeia; tumbling-like motion for Goniomonas pacifica; and nearly circular trajectories for Storeatula major. These distinct swimming behaviors may affect how cryptophyte species optimize the exploration of their environment depending on their trophic mode and could shape their survival strategies against predatory zooplankters. |
Sunday, November 20, 2022 5:53PM - 6:06PM |
J06.00007: Tracking plankton configurations during vertical migration at different densities Nina Mohebbi, Matthew K Fu, John O Dabiri Diel vertical migration of plankton is a significant synchronized biomass movement ubiquitous to earth’s oceans. The hydrodynamic interactions of swimmers in these swarms may impact the aggregation configuration and the nature of any swarm-scale flow features induced by the migration. |
Sunday, November 20, 2022 6:06PM - 6:19PM |
J06.00008: Quantifying coral larval behavior response to chemical cues in a microfluidic channel Koumudhi Deshpande, Daniel Gysbers, Gabriel Juarez Coral reef restoration often utilizes artificial substrates designed to induce settlement of coral larvae. These larvae use physical and chemical cues to navigate to a suitable habitat. However, the lack of quantitative data regarding the type and concentration of chemicals needed to trigger a behavioral response makes it difficult to engineer substrates that aid settlement. Here, we conduct chemotaxis experiments with Caribbean coral larvae in microfluidic chambers to study their response to different soluble inorganic (Magnesium, Strontium, and Calcium) and organic (Crustose coralline algae) chemical cues. Using particle tracking velocimetry, we quantify the positions, trajectories, and swimming speeds of larvae with respect to the chemical gradients. We augment this study by performing 2D simulations modeled after the experiments to characterize the chemical concentrations at which the larvae show behavioral changes. Our results enable the design of substrates that enhance larval settlement using chemical cues, improving their effectiveness in reef restoration. |
Sunday, November 20, 2022 6:19PM - 6:32PM |
J06.00009: Surface topography drives marine larval settlement through boundary layer flow interactions Daniel Gysbers, Mark Levenstein, Gabriel Juarez As invertebrate larvae approach marine surfaces, their motion is affected by interactions with the benthic boundary layer flow and surface topography. We performed 2D agent-based simulations of larval transport to investigate these effects on the movement and settlement of larvae. Surface features on the millimeter scale were examined using a ridged substrate as a model topography and by systematically varying the height and spacing of the ridges. Our simulations show that certain substrate topographies modify the boundary layer flow by creating vortices and ejecting them into the bulk flow. These flow structures increase larval transport towards the surface and enhance settlement. Interestingly, the optimal settlement substrates produced the highest averaged turbulent kinetic energy (TKE), indicating that passive larval transport due to recirculatory flow structures is a critical factor in settlement. This result is supported by simulated larval concentration profiles along the water column, which reveal clear differences in the efficiency of larval transport to the substrate arising from the different flow structures. Our findings thus demonstrate that TKE can be used as a predictor of larval settlement to inform substrate design. |
Sunday, November 20, 2022 6:32PM - 6:45PM |
J06.00010: Learning to blindly follow hydrodynamic trails Haotian Hang, Sina Heydari, Yusheng Jiao, Eva Kanso Many aquatic animals can follow hydrodynamic trails by sensing and responding to flow signals. Despite numerous studies on this topic, an understanding of how this behavior can be enacted using feedback control strategies that require only local and instantaneous flow sensing remains elusive. Here, we apply deep Reinforcement Learning to solve the problem of following vortical wakes to their generating source. We find that the trained swimmer reaches the source of the wake by turning towards larger flow speed, and that the location of the flow sensor is crucial for successful trail following. Through analysis in a reduced order signal field, we map the sensor location to the stability of the controller in locating the source. Importantly, the sensory control strategy is generalizable to thrust and drag wakes of different Strouhal and Reynolds numbers and to 3D wakes. This work emphasizes the importance of both sensor location and sensor type and has implication on other source seeking control problems with traveling-wave characteristic. |
Sunday, November 20, 2022 6:45PM - 6:58PM |
J06.00011: Fluid-based microbial processes modeling in Trichodesmium colonies Heng Wei, David A Hutchins, Paul D Ronney, Niema M Pahlevan In tropical and subtropical ocean gyres, Trichodesmium colonies account for up to half of the total N2 fixation in the ocean, making it one of the most ecologically significant N2 fixing cyanobacteria. Trichodesmium trichome colonies and large surface blooms formation have been studied relatively little in laboratory environments. More importantly, the flow motion effect has been ignored in previous studies. As the first step towards small-scale microbial processes associated with Trichodesmium synthesis, we present a shear-related fluid flow-based growth and synthesis model to better understand how fluid dynamics affect bacteria colony formation and growth. Under the assumption that early growth characteristics are strongly dependent on the shear rate, a two-way coupling fluid-structure interaction was developed using the lattice Boltzmann method for a porous colony. The results demonstrate that our model captures the exponential growth trend during the colony formation phase, and both the colony growth and the colony shape are dominated by the flow field. |
Sunday, November 20, 2022 6:58PM - 7:11PM |
J06.00012: Aggregation and breakage of cyanobacterial colonies Yuri Z Sinzato, Petra Visser, Jef Huisman, Maziyar Jalaal Harmful cyanobacterial blooms are a frequent nuisance in many freshwater bodies around the world. Microcystis is a common genus of colonial cyanobacteria which relies on its large colony size to achieve high flotation velocities. The colony size and morphology are strongly influenced by the local turbulence in the suspension, induced either by wind or artificial mixers. We investigate both numerically and experimentally the dynamics of colony formation under laminar and turbulent shear flows. Special attention is given to balance between cell division, aggregation and breakage. The experimental setup consists of the simultaneous use of rotational disks and microscopy. Colony shape, size distribution and moment kinetics are characterized by the laboratory culture of M. aeruginosa. The governing regimes are identified as a function of the main non-dimensional physical parameters. The results provide valuable criteria for the design of artificial mixing systems for bloom control. |
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