Article
Engineering, Multidisciplinary
Chao Zhou, Jianghao Wu
Summary: The study shows that the flexibility of the wing is crucial for the kinematics and aerodynamic performance of micro air vehicles; in a flexible wing, passive deformation is mainly caused by inertial forces, exhibiting a linear spanwise twist; flexible wing deformation can increase lift, enhance rotating moments, and improve power efficiency.
JOURNAL OF BIONIC ENGINEERING
(2021)
Article
Robotics
Songnan Bai, Qingning He, Pakpong Chirarattananon
Summary: This study adopts bioinspired principles to significantly reduce the power consumption of small unmanned aerial vehicles, enabling them to achieve hovering flight. By optimizing the design, the aircraft utilizes rotating wings and unsteady aerodynamics to improve flight efficiency while maintaining passive attitude stability. Compared to traditional multirotor robots, this drone consumes half the power and has a longer flight time.
Article
Mechanics
Yueyang Guo, Wenqing Yang, Yuanbo Dong, Jianlin Xuan
Summary: This paper investigates the mechanism and feasibility of generating sufficient lift using a simple motion at a certain frequency with a centimeter-scale flapping wing. The study shows that under certain frequency conditions, the flapping wing can effectively generate the necessary aerodynamic force to sustain flight on this scale.
Article
Engineering, Aerospace
Jianghao Wu, Xinyi Wu, Peng Tang, Yanlai Zhang, Chao Zhou
Summary: This study analyzed the hovering stability of a 30 g flapping-rotary-wing (FRW) prototype and found that it has two unstable modes: an unstable oscillatory mode and a slow divergence mode. The distinction between FRW and helicopters lies in the longitudinal-lateral coupling and rotational-vertical coupling in their modal characteristics.
Article
Engineering, Mechanical
Sevak Tahmasian
Summary: This paper discusses the effects of wing inertial forces on flight stability and required lift for insects with a varying stroke plane. The study shows that wing inertial forces have destabilizing effects on the insect's translational motion during hover, and insects with a varying stroke plane require less aerodynamic lift than their weight and a nonzero-mean drag for a stable hovering flight.
NONLINEAR DYNAMICS
(2023)
Article
Biology
Suyash Agrawal, Bret W. Tobalske, Zafar Anwar, Haoxiang Luo, Tyson L. Hedrick, Bo Cheng
Summary: The study found that hummingbirds use their unique musculoskeletal system and wing motion ability to achieve hover and flight control, and developed a functional model to predict torque and contraction behavior of muscles. Primary muscles act as engines, not only driving wing motion but also actively deviating and pitching the wings, while secondary muscles act against primary muscles through controlled-tightening effects.
PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES
(2022)
Article
Engineering, Multidisciplinary
Jinjing Hao, Jianghao Wu, Yanlai Zhang
Summary: Passive wing pitching is a hypothesis in insect flight and is widely used by most FWMAVs. This study analyzes the flight control of a hovering model fruit fly and FWMAV with passive pitching wings, finding that control derivatives are significantly influenced by passive pitching wings. The study provides guidelines for evaluating different control inputs and designing cost-effective control schemes for FWMAVs.
BIOINSPIRATION & BIOMIMETICS
(2021)
Article
Thermodynamics
Y. Zhang, Z. Wang, H. Zheng
Summary: This research explores bionic propulsion technology to develop an improved flapping wing micro air vehicle (FWMAV) design, inspired by the flight dynamics of flying insects and birds. The study involves the preliminary design of a prototype to achieve multi-attitude flight using a bionic formula, kinematic modeling for data analysis, and the adoption of a meshless particle hydrodynamics method to optimize the flapping driving mechanism and understand its influence on aerodynamic performance. Based on the aerodynamic model, force measurement experiments are conducted to verify simulation availability and investigate the importance of wing flexibility. The results show that the average lift is proportional to the flapping frequency, amplitude, and quick-return characteristics, and further optimization is conducted to find the best design parameters.
JOURNAL OF APPLIED FLUID MECHANICS
(2023)
Article
Robotics
Yogesh M. Chukewad, Sawyer Fuller
Summary: This paper introduces three innovations that increase yaw actuation torque and validates these results through simulation and experiment. These innovations include a new two-actuator robot design, wider actuators, and a phase shift to the second harmonic signal.
IEEE ROBOTICS AND AUTOMATION LETTERS
(2021)
Article
Engineering, Aerospace
Xinyu Lang, Bifeng Song, Wenqing Yang, Xiaojun Yang, Dong Xue
Summary: This study analyzed the influence of wing shape and flapping motion on the hovering flight of flapping wing micro air vehicles (FWMAVs). A sensitivity analysis was conducted to evaluate the degree of influence of each parameter on aerodynamic performance, and exponential relationships were established between the parameters and aerodynamic properties. The results showed that wing area had the largest influence on lift, and the distribution of area had the most significant effect on aerodynamic power. Flapping frequency had a greater impact on lift growth and power loading, while the shape of the flapping motion primarily influenced lift and power loading, and the sweeping motion dominated power consumption.
Article
Engineering, Aerospace
James L. Lankford, Inderjit Chopra
Summary: Instantaneous force and structural deformation experiments were conducted on a flexible flapping wing, and compared with computational fluid dynamics/computational structural dynamics (CFD/CSD) analysis. The results showed that decreasing wing stiffness can improve wing performance.
JOURNAL OF AIRCRAFT
(2022)
Article
Engineering, Multidisciplinary
Xueguang Meng, Xinyu Liu, Zengshuang Chen, Jianghao Wu, Gang Chen
Summary: In this study, wing damage was simulated in droneflies (Eristalis tenax) by performing successive unilateral and bilateral wing shearing. The wing kinematics were measured using high-speed photography technology. Different shearing methods had minimal impact on the kinematics, forces, and energy consumption of the insects. Adjusting the stroke angle (phi) in isolation or combining it with the pitch angle (psi) contributed the most to the change in vertical force following wing damage. The insects may alleviate the problems of increasing power consumption and asymmetric power distribution by storage and reuse of the negative inertial work of the wing.
BIOINSPIRATION & BIOMIMETICS
(2023)
Article
Multidisciplinary Sciences
Liansong Peng, Mengzong Zheng, Tianyu Pan, Guanting Su, Qiushi Li
Summary: The interactions between tandem-wings of dragonflies play a significant role in affecting the aerodynamic performance of hovering flight. These interactions result in a reduction of lift coefficient and aerodynamic power, mainly caused by the vortex structures between the forewing and hindwing. The phase difference between the wings also affects the lift production and efficiency of dragonflies during hovering, with different phase differences resulting in varying lift outputs.
ROYAL SOCIETY OPEN SCIENCE
(2021)
Article
Engineering, Multidisciplinary
Xueguang Meng, Anas Ghaffar, Yang Zhang, Chengjian Deng
Summary: This study investigates the ground effect trend of a three-dimensional flapping insect wing at a very low Reynolds number (Re = 10). It demonstrates that at this Re, the ground effect trend has a 'single force regime' unlike the expected 'three force regimes' at higher Reynolds numbers. The trend correlates to wing-wake interaction or downwash strength.
BIOINSPIRATION & BIOMIMETICS
(2021)
Article
Engineering, Aerospace
Qian Li, Jiwei Yuan, Huan Shen, Jiaguo Deng, Timothy R. Jakobi, Sridhar Ravi, Xiaoyi Wang, Aihong Ji
Summary: This study introduces a new quasi-flapping wing driving mechanism based on a half-rotating mechanism capable of pure rotational flapping for hovering flight. Experimental assessments were done for different wing layouts and materials, showing that the average lift coefficient of the flexible wing is higher than that of the rigid wing and increases with flexural compliance within a certain range. Results also indicated that the flow field interference between symmetrically arranged wings impacts the lift coefficient of the HRW, showcasing the importance of velocity difference in generating vortices during hovering flight.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART G-JOURNAL OF AEROSPACE ENGINEERING
(2021)
Article
Mechanics
Mehdi Vahab, David Murphy, Kourosh Shoele
Summary: This study investigates the physics of the impact of snow and hail particles on liquid surfaces using a numerical model. The melting rate and air content of the particles are found to be key factors affecting the formation of vortex rings and the transportation of gas bubbles. Water temperature plays a significant role in phase change and thermal transport, while particle temperature has minimal effect. The Reynolds, Weber, and Stefan numbers have different effects on the flow dynamics of snow particles.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Chemistry, Physical
Qiang Zhu, Xiaobo Bi
Summary: This study numerically investigates the dynamic response of erythrocytes in oscillatory shear flows, focusing on membrane shear deformation and skeleton-bilayer dissociation stress. It revealed that the variation in surface area-to-volume ratio can lead to significant changes in the occurrence of response modes, highlighting the importance of understanding the dependencies of skeleton deformation and stress on S/V ratio for applications such as diagnosis.
Review
Engineering, Multidisciplinary
Qiang Zhu, Qing Xiao
Summary: The article summarizes existing studies on underwater jet propulsion, ranging from investigations on the underlying physics to the creation of mechanical systems utilizing this locomotion mode. Research directions that worth future investigation are also discussed.
BIOINSPIRATION & BIOMIMETICS
(2022)
Article
Engineering, Multidisciplinary
Oluwafemi Ojo, Kourosh Shoele
Summary: This study investigates the role of flexibility and branching patterns of trees in their reconfiguration and stress mitigation capabilities using a numerical model. The results show that the breaking risk of trees from the stem to terminal foliage strongly depends on the cross section changes in the branching nodes, the overall tree geometry, and the level of tree flexibility. The optimal branching pattern for both flexible and rigid trees is to have a uniform stress distribution throughout the tree's height, except for very flexible branched plants which are strongly influenced by the reconfigurability of the tree.
BIOINSPIRATION & BIOMIMETICS
(2022)
Article
Mechanics
Oluwafemi Ojo, Yu-Cheng Wang, Alper Erturk, Kourosh Shoele
Summary: The fluttering response of heavy inverted flags with different aspect ratios is studied to understand how vortical structures influence the intermittent vibration response of the flag. Experimental and numerical results show that there is significant hysteretic bistability between different oscillatory modes, which is caused by the distinct roles of vortices around the flag. The interaction between the flexible plate and the vortices is quantified and it is found that the aspect ratio can significantly alter the hysteresis behavior and bistable response of the flag.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Shijian Wu, Tomas Solano, Kourosh Shoele, Hadi Mohammadigoushki
Summary: In this study, we investigate the effects of helical swimmer shape on swimming dynamics in a constant viscosity viscoelastic fluid. The results show that increasing the swimmer's tail thickness and pitch angle enhances the swimming speed. Furthermore, a front-back flow asymmetry is observed in the viscoelastic flow around the swimmer, and the strength of the negative wake is inversely proportional to the swimming speed. Simulations confirm the formation of a similar front-back flow asymmetry. Finally, the contribution of polymer stresses in the interior region of the helix may provide a mechanism for swimming enhancement or diminution in the viscoelastic fluid.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Xiaobo Bi, Hui Tang, Qiang Zhu
Summary: By investigating the fluid dynamics of a salp-like swimmer, it is shown that coordinated shell inflation/deflation and valve opening/closing can create uni-directional flow for forward motion, reducing energy loss and allowing for energy recovery among different body parts. This phenomenon also suggests passive activation of valves by harvesting energy spent by the shell, simplifying mechanical design for sustained locomotion.
Article
Mechanics
Tomas Solano, Chuanxin Ni, Rajat Mittal, Kourosh Shoele
Summary: The effectiveness of face masks depends on both the material and the fit on faces. A new model for masks is presented to study the leakage pattern on realistic faces. Higher porosity reduces leakage.
Article
Physics, Fluids & Plasmas
Tso-Kang Wang, Kourosh Shoele
Summary: This paper investigates the regulation of the plunging response of a foil with the use of an active flap, improving structural safety and energy extraction efficiency. The competition between active flap-induced and flow-induced modes dictates the foil's response. The active flap can modulate the vortex shedding and regulate the foil's motion, making it a good candidate for active flow control.
PHYSICAL REVIEW FLUIDS
(2022)
Article
Engineering, Multidisciplinary
Brian Van Stratum, Kourosh Shoele, Jonathan E. Clark
Summary: Researchers have developed a new robot locomotion inspired by the Pacific lamprey that allows the robot to climb on flat and near-vertical surfaces with the ability to steer. The experimental results demonstrate that this climbing strategy is effective for snake robots climbing on near-vertical surfaces with limited push points.
BIOINSPIRATION & BIOMIMETICS
(2023)
Article
Physics, Multidisciplinary
Farshad Nazari, Kourosh Shoele, Hadi Mohammadigoushki
Summary: We present a study on the locomotion of a helical swimmer in yield stress fluids, which involves three stages. In the first stage, the swimmer needs to overcome the yield strain of the material to achieve rotational motion. However, surpassing the first threshold alone does not lead to locomotion. Only when the viscous forces are strong enough to cause plastic deformation of the material, resulting in movement away from the swimmer, can net locomotion occur. In the third stage of locomotion, the yield stress affects swimming differently at small and large pitch angles, retarding or enhancing the swimming speed respectively. Flow visualizations demonstrate highly localized flow near the swimmer in yield stress fluids.
PHYSICAL REVIEW LETTERS
(2023)
Article
Physics, Fluids & Plasmas
Tso-Kang Wang, Kourosh Shoele
Summary: In this study, a novel approach called Kernel Mode Decomposition (KMD) with a sparsification network is proposed to identify and track fluid responses with transitional behaviors. The method is demonstrated using synthetic problems and a lid-driven cavity flow problem, showing its ability to capture changing amplitude and frequencies. Additionally, the proposed method is applied to examine the formation process of a laminar separation bubble, revealing multiple competing mechanisms involved.
PHYSICAL REVIEW FLUIDS
(2023)
Article
Mechanics
Kourosh Shoele
Summary: We studied the dynamics and energy production capability of a flexible piezoelectric plate submerged close to the free surface and exposed to incident head gravity waves and current. A theoretical model was derived to describe the hydrodynamic interactions between the plate, its wake, gravity incident waves, and the current. The model revealed two distinct vibration states of the plate, with different dependencies on plate flexibility and optimal energy production levels. The role of the Froude number in system responses and the submergence depth required for high energy conditions in subcritical and critical flows were also investigated. Proper matching between flow, mechanical, and electrical time scales was found to be important for optimal energy production.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Mechanics
Chuanxin Ni, Tomas Solano, Kourosh Shoele, Jung-Hee Seo, Rajat Mittal
Summary: This model incorporates empirical data on filtration efficiency and the size distribution of exhaled aerosol particles to estimate the extent of peripheral leakage and the fitted filtration efficiency of face masks. The simulations show that surgical masks have significant peripheral leakage but can still filter out approximately 70% of exhaled particles.
Article
Physics, Fluids & Plasmas
Brian Van Stratum, Jonathan Clark, Kourosh Shoele
Summary: This study investigates the effect of internal damping on the locomotion performance of a crawler robot. It is found that by varying the internal damping, the performance and gaits of the robot can be altered, including changing the locomotion direction. The study also identifies the optimal internal damping for peak crawling speed.
