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 L04: Animal Flight: Flying Insects II |
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Chair: Chengyu Li, Villanova University Room: 131 |
Monday, November 21, 2022 8:00AM - 8:13AM |
L04.00001: Effects of flight speed on olfactory sensitivity in upwind surging flights of a hawkmoth Seth Lionetti, Tyson L Hedrick, Chengyu Li In nature, flying insects rely on odor-guided navigation to perform a variety of tasks, including finding mates, locating food, and detecting predators. Their flapping wings can potentially draw more odor plumes towards their antennae, thereby enhancing their olfactory sensitivity. However, insects’ flapping wing kinematics drastically change as flight speed increases. It is unclear how varying an insect’s flight speed impacts its odorant perception. In this study, we reconstructed wing kinematics of a hawkmoth at both 2 m/s and 4 m/s using high-speed video recordings. Then, CFD simulations were adopted as a non-intrusive approach to investigate the unsteady flow field by solving the Navier-Stokes equations and the odorant transport process by solving the advection-diffusion equations. Results show that hawkmoths use their wings to increase the odor intensity around their antennae. At both flight speeds, odor intensity is enhanced and synchronized with the flapping motion. Compared with the 4 m/s case, the peak odor intensity is approximately 39% higher during the 2 m/s flight. We suspect that lower flying speed can enhance the olfactory sensitivity of hawkmoth in odor-tracking flights. |
Monday, November 21, 2022 8:13AM - 8:26AM |
L04.00002: Study the wake flow of small insect, with the schlieren photography and particle tracking velocimetry Yun Liu, Angel David Galarza Utilizing high-speed schlieren photography and particle-image-velocimetry, the wake flow of tethered houseflies is investigated. The high-speed schlieren photography is implemented on tethered houseflies inside an air container with a stable vertical temperature gradient to visualize the disturbed wake flow from the insects. The resulting photography images were then processed with the physics based optical flow method to derive the light-path averaged flow velocity. Additionally, the state of the art: Shake-the-Box system is implemented on a tethered housefly to measure the volumetric flow field in the wake of the insect, revealing interesting flow behavior and structures that can also be observed and correlated to the schlieren photography experiment results. Comparing the dimensionless velocity magnitude of the wake flow from the two experiments, a good qualitative agreement is reached, suggesting the viability of high-speed schlieren photography in investigating the wake flow of small insects. Furthermore, the high-speed schlieren photography is successfully applied on a housefly that is taking off from the ground, visualizing the disturbed wake flow on the freely flying insect that is challenging to achieve with other methods. |
Monday, November 21, 2022 8:26AM - 8:39AM Author not Attending |
L04.00003: Mosquito flight in turbulent airflow Intesaaf Ashraf, Florian Muijres, Martin J Lankheet, Spitzen Jeroen, Jos Zeegers, Rolands J Geraerts Mosquitoes are the world's deadliest animals as they spread many deadly human diseases through biting. To reduce or prevent this biting, we need to properly understand the in-flight host search behaviour of mosquitoes. However, most of the studies on the host searching behaviour of mosquitoes have been performed in low-turbulence wind tunnels or in unknown turbulence conditions. These studies have identified the flight dynamics of host-searching mosquitoes well, but how natural airflow turbulence affects this behaviour is not yet known. Therefore, to determine this, we performed host-search flight experiments with malaria mosquitoes in a wind tunnel, at both a low and high turbulence intensity (5% and 20%, respectively). We produced the increased turbulence intensity conditions using a turbulence generator and quantified it using hotwire anemometry. We tracked the flight dynamics of the host-searching malaria mosquitoes using a real-time machine-vision-based tracking system. By comparing the flight kinematics between mosquitoes flying in low and high turbulence conditions, we determined how turbulence affects host-searching dynamics and performance. The outcome of this study can be used to develop new and improved malaria vector control tools and strategies. |
Monday, November 21, 2022 8:39AM - 8:52AM |
L04.00004: Descending neuronal pathways for aerodynamic control in Drosophila Emily H Palmer, Jaison J Omoto, Anne Erickson, Michael H Dickinson To maintain controlled flight, animals and aerial vehicles alike must execute continuous trimming adjustments to compensate for internal and external perturbations, such as physical asymmetries or sudden gusts. Flying animals make use of a PID-like control strategy, using visual, inertial, and proprioceptive cues to determine deviations from the desired speed and flight path and adjust accordingly. Prior work in the fruit fly Drosophila melanogaster identified a population of neurons descending from the brain to the ventral nerve cord, the DNg02s, that collectively regulate wing stroke amplitude over a large dynamic range and appear to be involved in visually-mediated flight stabilization. We present additional findings illuminating the function of these important neurons in flight control. Our experiments exploit the optomotor response, a behavior in which fruit flies steer to minimize wide-field optic flow, which is quantified in tethered flies as a difference in the left and right wingbeat amplitudes. Using a suite of genetic tools to selectively silence various subsets of the population, we found a clear negative linear relationship between the number of DNg02 neurons silenced and the magnitude of the optomotor response, suggesting that the animals adjust the strength of this reflex via recruitment of different numbers of the descending cells. We then utilized high speed videography to track the wings while activating neurons in the population to determine the precise changes in stroke amplitude, stroke plane deviation, wing pitch, and wing deformation. Using a dynamically scaled physical model of a fly wing, we measured the changes in forces and moments associated with the recorded kinematic changes. This interdisciplinary study of flight control in Drosophila provides new insight into the neural mechanisms by which animals implement control strategies during locomotion. |
Monday, November 21, 2022 8:52AM - 9:05AM |
L04.00005: Transient perfusion through a microfluidic dragonfly wing vein model Sangjin Ryu, Haipeng Zhang, Mary K Salcedo, John J Socha, Günther Pass Insect wings include a network of tubular veins through which hemolymph (blood) flows to provide the sensory organs and other tissues with water and nutrients and to remove waste products. Thus, hemolymph flow through veins is important for stability and functionality of the fragile wing blade. However, the perfusion through wing venation has been poorly studied because tracing hemocytes (blood cells) in veins of living specimen provides limited information about flow patterns. To characterize transient perfusion through complex wing venation, we created a microfluidic wing vein model of the dragonfly, Anax junius. Hemolymph flow was simulated by injecting red dye into the device filled with water at a range of flow rates. Visualized perfusion patterns suggested that the perfused area in the device logarithmically increased with time. When water was injected into the device filled with the dye, perfusion occurred slower with different patterns, and the time dependence of the perfused area was not logarithmic. The observed difference suggests that perfusion does not occur uniformly throughout the wing vein network. |
Monday, November 21, 2022 9:05AM - 9:18AM |
L04.00006: Aerodynamic Characteristics of Rotating Beetle Wings Tanner E Saussaman, Roi Gurka, Gal Ribak Ariel insects, a low Reynolds number flyer, feature various flight mechanisms (flapping wings, multiple wings motions, etc.). Insects’ wings are configured in various forms over the body, with different shapes and proximities to each other. When an insect flap its wings, it generates two distinct wakes: one from each of its wings. If the wings are located closely, their proximity will cause an interaction between the two wakes in the near field. One open question is: How does this interaction affect aerodynamic loads as well as the wake flow dynamics, during forward flight? We study this flight mode, at low Reynolds numbers and body/wing ratio, by using a rotating wing reference frame to perform controlled experiments that will simulate the motion. With a set of wings locked to the same axis and planar height, the effect of the wake generated by one wing on another can be observed. Experiments were performed using a 3D-PTV (particle tracking velocimetry) system in a closed glass chamber where an electrical motor was used to rotate a set of beetle wings. Using a 3D system allows for measuring of all velocity components of the flow around the rotating wings creating a volume of information. The beetle wings used in the experiments were from the species Batocera rufomaculata. This species has several morphological features that can be altered to perform ample experimentation such as size of the wings and angle of attack (AoA). By characterizing the aerodynamic performance, understanding of the impact of wing orientation (i.e., AoA), wing size, and distance between wings on the wake-flow dynamics and their interactions (i.e.: constructive or destructive) can be achieved. |
Monday, November 21, 2022 9:18AM - 9:31AM |
L04.00007: Flow and Wing Kinematics Measurements of a Tiny Insect in Flight Evan J Williams, John Murray-Bruce, David W Murphy Tiny sub-millimeter insects in flight use the clap and fling mechanism to generate lift, but the aerodynamics of this mechanism are not well understood owing to the small spatial and fast temporal scales involved and the difficulty of experimentally observing the flow around the insect’s wings. To examine tiny insect flight, we implemented a novel ultra-high speed brightfield micro PIV system to measure time-resolved (10 kHz) flows generated by a freely flying sweet potato whitefly (Bemisia tabaci). A computational algorithm that solves a sparsity-regularized linear inverse problem was used to extract the in-focus particles from PIV images. Additionally, two orthogonal synchronized cameras were used to implement 3D stereophotogrammetry to determine the insect’s position in the PIV measurement plane and measure 3D wing kinematics. The whitefly has a body length of 0.8 mm, forewing length of 0.9 mm, hindwing length of 0.75 mm, stroke amplitude of 123°, beat frequency of 150 Hz, and chordwise Reynolds number of 14. We present fields of the clap and fling, which reveals a downwards jet ejected from between the wings with flow speeds up to 400 mm/s during clap, a medial spanwise flow during the fling as the wings create a V-shaped gap, and an induced vorticity during the power stroke. |
Monday, November 21, 2022 9:31AM - 9:44AM |
L04.00008: Design of an Efficient Mosquito Trap Using Fluid Dynamics Christopher Zuo, Soohwan Kim, Sze Hou Loh, David L Hu, Ring T Carde Mosquitoes are arguably the most dangerous animals on the planet, transmitting diseases such as malaria, dengue virus, and Zika, and causing millions of deaths every year. The ability to trap and survey intact mosquitoes is important for monitoring their populations. Despite a century of mosquito trap design, a trap's efficiency, the proportion captured of those lured to the trap, is often low, ranging from <10% to 58%. We present the design of a mosquito trap in which the bait odor plume is closer to the suction port. In previous systems, trajectories show many mosquitoes are initially attracted to the bait plume and then leave the vicinity without being sucked into the trap. We test our trap design using live mosquito experiments and computational fluid dynamics simulations. We discuss iterations of our design based upon consideration of plume streamlines and mosquito behavior. |
Monday, November 21, 2022 9:44AM - 9:57AM |
L04.00009: Parachuting at low Reynolds number with bristled wings Arvind Santhanakrishnan, Vishwa Teja Kasoju Miniature flying insects such as thrips have been observed to intermittently cease flapping and float passively downwards by spreading their bristled wings. This type of drag-based parachuting can lower their falling speed and aid in long-distance dispersal. Though bristled wings have been shown to reduce drag in the flapping flight of tiny insects, it is unknown whether bristled wings also reduce drag during parachuting. Forewing inter-wing angle (θ) of 97.4° was measured from a published video of parachuting thrips, along with a falling speed of 0.6 m/s and span-based Reynolds number (Res) of 40. Numerical simulations of steady flow past a non-bristled wing pair and two bristled wing pairs varying in the number of bristles were used to examine drag coefficients (CD) and inter-bristle flows, for Res ranging from 20-400 and θ ranging from 20°-180°. Force measurements were conducted on equivalent physical models that were towed in an 8-foot long fluid-filled tank. Irrespective of wing design, fluid barriers were observed within inter-bristle gaps at Res=20. These fluid barriers maintained constant aerodynamic loading for θ ≥ 100° by maximizing drag force and minimizing leakiness. Irrespective of Res, densely bristled wings provided maximum aerodynamic loading for θ ≥ 100°. |
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