We investigate how flapping wings generate aerodynamic forces through the formation, evolution and interaction of vortices. Our research has revealed how regular wing motions can produce chaotic wakes and unpredictable aerodynamic loads. We have identified disturbances in the leading-edge vortex as a primary trigger for the transition from ordered to chaotic flow: small irregularities can progressively disrupt an organised wake, with spontaneously formed vortex pairs and subsequent vortex interactions sustaining the breakdown. By connecting these near-wing processes with downstream wake behaviour, we have established a dynamic link between near- and far-field transitions and identified wake jet-switching as an important precursor to chaos. These contributions provide a physical framework for understanding unsteady force generation and inform the design of flapping-wing systems with more predictable aerodynamic performance.

Relevant Publications

• Badrinath, S., Bose, C., & Sarkar, S. (2017). Identifying the route to chaos in the flow past a flapping airfoil. European Journal of Mechanics–B/Fluids, 66, 38–59. https://doi.org/10.1016/j.euromechflu.2017.05.012
• Bose, C., & Sarkar, S. (2018). Investigating chaotic wake dynamics past a flapping airfoil and the role of vortex interactions behind the chaotic transition. Physics of Fluids, 30(4), Article 047101. https://doi.org/10.1063/1.5019442
• Majumdar, D., Bose, C., & Sarkar, S. (2020). Effect of gusty inflow on the jet-switching characteristics of a plunging foil. Physics of Fluids, 32(11). https://doi.org/10.1063/5.0024084
• Bose, C., Gupta, S., & Sarkar, S. (2021). Dynamic interlinking between near- and far-field wakes behind a pitching–heaving airfoil. Journal of Fluid Mechanics, 911, Article A31. https://doi.org/10.1017/jfm.2020.1030
• Majumdar, D., Bose, C., & Sarkar, S. (2022). Transition boundaries and an order-to-chaos map for the flow-field past a flapping foil. Journal of Fluid Mechanics, 942, Article A40. https://doi.org/10.1017/jfm.2022.385
• Cavanagh, A., Bose, C., & Ramesh, K. (2024). Effect of sweep angle on three-dimensional vortex dynamics over plunging wings. Physics of Fluids, 36(11), Article 117115. https://doi.org/10.1063/5.0227012

We explore how the diversity of butterfly wing shapes influences three-dimensional vortex dynamics and aerodynamic performance. Our comparative simulations of Swallowtail-, Indian leaf- and Monarch-inspired wings reveal how wing geometry changes the development and interaction of leading-edge, trailing-edge and wing-tip vortices. We have identified differences in vortex persistence, spanwise circulation and aerodynamic force generation across these geometries, demonstrating that stronger vortices do not necessarily produce higher peak lift. This work provides a physical basis for selecting wing shapes for butterfly-inspired micro aerial vehicles.

Relevant Publications

• Shergill, A., Roy, S., & Bose, C. (2026). Comparitive study of wing-wake interactions across butterfly species [Conference abstract]. Platinum Jubilee International Conference on Multiphysics, Multifunctional and Multiscale Phenomena in Mechanics, December 17–20, 2026, IIT Kharagpur, India.

We investigate how controlled shape changes and passive structural deformation can improve wing performance in unsteady flows. Our studies have demonstrated that flexible trailing edges can suppress wake jet-switching and restore more regular flow patterns, while bird-inspired foil geometries exhibit distinct responses to accelerated motion. We have shown that the benefits of flexibility depend on wing shape, stiffness and the extent of the flexible region. Building on these findings, our ongoing research examines how active actuation and passive compliance can work together to manage aerodynamic loads and adapt to changing flight conditions.

Relevant Publications

• Saddal, H., Jayswal, L. B., & Bose, C. (2026). Effects of plunging acceleration on the passive morphing of avian-inspired flexible foils [Preprint]. arXiv. https://doi.org/10.48550/arXiv.2603.27794
• Shah, C. L., Majumdar, D., Bose, C., & Sarkar, S. (2022). Chordwise flexible aft-tail suppresses jet-switching by reinstating wake periodicity in a flapping foil. Journal of Fluid Mechanics, 946, Article A12. https://doi.org/10.1017/jfm.2022.591
• Shah, C. L., Majumdar, D., Bose, C., & Sarkar, S. (2024). Controlling the chaotic wake of a flapping foil by tuning its chordwise flexibility. Journal of Fluids and Structures, 127, Article 104134. https://doi.org/10.1016/j.jfluidstructs.2024.104134

We investigate how wing flexibility influences aerodynamic loads, structural deformation and vortex dynamics during gust encounters. Using coupled fluid–structure interaction simulations, we examine how wing geometry, stiffness and the distribution of flexible regions govern the response to unsteady disturbances. Our studies of bird-inspired foils under accelerated motion have identified geometry-dependent optimal stiffness levels, demonstrating that the benefits of flexibility depend on how deformation interacts with vortex formation and force generation. Building on these findings, we explore how passive wing adaptation can moderate load fluctuations and improve aerodynamic stability, providing design principles for lightweight aerial vehicles operating in gusty environments.

We study how freely moving bodies respond to gusts through the coupled evolution of their motion and surrounding flow. Our research on free-falling plates has revealed how transverse gusts generate circulation and displace the body relative to its wake, increasing upward aerodynamic forces and temporarily reducing descent speed. We have also established how pitching motion, body density and gust strength govern this response. These findings explain how passive flyers can extract energy from environmental disturbances to remain aloft longer, informing the development of lightweight aerial sensing and dispersal systems.

Relevant Publications

• Pandi, J. S. S., Gungor, A., Bose, C., Attili, A., & Viola, I. M. (2026). Effect of transverse gust on free-falling plates. Journal of Fluid Mechanics, 1040, Article A23. https://doi.org/10.1017/jfm.2026.11850

We investigate the complex oscillations that emerge when aerodynamic forces interact with structural nonlinearities. Through numerical modelling and wind-tunnel experiments, our work has characterised instability transitions in pitching–plunging aerofoils, including the effects of dynamic stall, structural freeplay and fluctuating inflow. We have used synchronisation between structural modes to explain how these instabilities develop and how changes in structural parameters alter their behaviour. Our studies also connect unsteady response with fatigue damage, contributing to a deeper understanding of the stability and durability of flexible aerodynamic structures.

Relevant Publications

• Bose, C., Gupta, S., & Sarkar, S. (2019). Transition to chaos in the flow-induced vibration of a pitching-plunging airfoil at low Reynolds numbers: Ruelle–Takens–Newhouse scenario. International Journal of Non-Linear Mechanics, 109, 189–203. https://doi.org/10.1016/j.ijnonlinmec.2018.11.012
• Tripathi, D., Bose, C., Mondal, S., & Venkatramani, J. (2025). Effect of structural parameters on the synchronization characteristics in a stall-induced aeroelastic system. Journal of Fluids and Structures, 133, Article 104246. https://doi.org/10.1016/j.jfluidstructs.2024.104246
• Tripathi, D., Shreenivas, R., Bose, C., Mondal, S., & Venkatramani, J. (2022). Experimental investigation on the synchronization characteristics of a pitch-plunge aeroelastic system exhibiting stall flutter. Chaos: An Interdisciplinary Journal of Nonlinear Science, 32(7), Article 073114. https://doi.org/10.1063/5.0096213
• Tripathi, D., Vishal, S., Bose, C., & Venkatramani, J. (2022). Stall-induced fatigue damage in nonlinear aeroelastic systems under stochastic inflow: Numerical and experimental analyses. International Journal of Non-Linear Mechanics, 142, Article 104003. https://doi.org/10.1016/j.ijnonlinmec.2022.104003
• Vishal, S., Raaj, A., Bose, C., & Venkatramani, J. (2021). Routes to synchronization in a pitch–plunge aeroelastic system with coupled structural and aerodynamic nonlinearities. International Journal of Non-Linear Mechanics, 135, Article 103766. https://doi.org/10.1016/j.ijnonlinmec.2021.103766
• Vishal, S., Raaj, A., Bose, C., Venkatramani, J., & Dimitriadis, G. (2022). Numerical investigation into discontinuity-induced bifurcations in an aeroelastic system with coupled non-smooth nonlinearities. Nonlinear Dynamics, 108(4), 3025–3051. https://doi.org/10.1007/s11071-022-07352-3

We examine how vortex shedding and fluid–structure coupling drive the oscillations of bluff bodies and flexible structures. Our research has shown how neighbouring bodies, wake interference and intermittent structural contact can change vibration amplitudes and trigger transitions between regular, irregular and galloping responses. We have also investigated passive vibration suppression using nonlinear energy sinks, explaining how energy transfer can reduce large oscillations. Together, these contributions clarify the mechanisms governing flow-induced response and provide guidance for managing vibrations in engineering systems.

Relevant Publications

• Chawla, R., Rounak, A., Bose, C., & Pakrashi, V. (2024). Wake-induced response of vibro-impacting systems. Physics of Fluids, 36(12), Article 127148. https://doi.org/10.1063/5.0236147
• Chirathalattu, A. T., Santhosh, B., Bose, C., Philip, R., & Balaram, B. (2023). Passive suppression of vortex-induced vibrations using a nonlinear energy sink—Numerical and analytical perspective. Mechanical Systems and Signal Processing, 182, Article 109556. https://doi.org/10.1016/j.ymssp.2022.109556
• Jha, H., Saddal, H., & Bose, C. (2026). Efficacy of the weak formulation of sparse nonlinear identification in predicting vortex-induced vibrations [Preprint]. arXiv. https://doi.org/10.48550/arXiv.2603.27840
• Wang, J., Li, S., Yurchenko, D., Zhu, H., & Bose, C. (2024). Effect of a fixed downstream cylinder on the flow-induced vibration of an elastically supported primary cylinder. Physics of Fluids, 36(6), Article 063602. https://doi.org/10.1063/5.0207136

We investigate how squid-inspired flexible nozzles enhance pulsed-jet propulsion through the coupling of fluid flow and structural deformation. Combining biological observations, experiments and three-dimensional fluid–structure interaction simulations, our collaborative work has shown that a compliant nozzle can store elastic energy during jet acceleration and release it through carefully timed recoil, amplifying propulsive impulse. We have linked travelling deformation waves to fluid entrainment, jet acceleration and vortex-ring formation, and developed reduced-order models to explain these mechanisms. Our optimisation studies reveal trade-offs between thrust and energy expenditure, identifying flexible-nozzle designs that improve propulsion efficiency. These findings inform the development of soft underwater thrusters and bio-inspired robotic propulsion systems.

Relevant Publications

• Choi, D., Singh, P., Bergerson, I., Kim, M., Park, J., Wallace, H. J., Zhang, K., Hsieh, S. Y., Asberry, A. T., Uyeno, T. A., Gilly, W. F., Park, H., Kang, D., Bose, C., & Bhamla, S. (2026). Squid funnels time their elastic recoil to amplify pulsed jets [Preprint]. arXiv. https://doi.org/10.48550/arXiv.2605.03239
• Choi, D., Singh, P., Bhamla, S., & Bose, C. (2026). Computational and reduced-order modelling of elastic wave-driven impulse enhancement in pulsed jets through passively flexible nozzles [Preprint]. arXiv. https://doi.org/10.48550/arXiv.2605.17319
• Singh, P., Karki, Y., Hernandez, V., Choi, D., Bhamla, S., & Bose, C. (2026). Multi-objective Bayesian optimization of rigid and flexible nozzles for energy-efficient pulsed jet propulsion [Preprint]. arXiv. https://doi.org/10.48550/arXiv.2606.19252

We combine physical understanding with data-driven methods to develop compact models and guide the design of fluid–structure interaction systems. Our work has evaluated sparse equation discovery and its weak formulation for vortex-induced vibrations, alongside modal approaches for representing wake dynamics. These studies identify both the promise and the limitations of reduced descriptions, particularly for irregular responses. We also apply multi-objective Bayesian optimisation to rigid and flexible propulsion nozzles, examining trade-offs between thrust, energy use and efficiency to support more informed design decisions.

Relevant Publications

• Choi, D., Singh, P., Bhamla, S., & Bose, C. (2026). Computational and reduced-order modelling of elastic wave-driven impulse enhancement in pulsed jets through passively flexible nozzles [Preprint]. arXiv. https://doi.org/10.48550/arXiv.2605.17319
• Jha, H., Saddal, H., & Bose, C. (2026). Efficacy of the weak formulation of sparse nonlinear identification in predicting vortex-induced vibrations [Preprint]. arXiv. https://doi.org/10.48550/arXiv.2603.27840
• Singh, P., Karki, Y., Hernandez, V., Choi, D., Bhamla, S., & Bose, C. (2026). Multi-objective Bayesian optimization of rigid and flexible nozzles for energy-efficient pulsed jet propulsion [Preprint]. arXiv. https://doi.org/10.48550/arXiv.2606.19252

We investigate how flow through a body changes its aerodynamic forces and wake dynamics. Our studies of porous plates and permeable disks have revealed how permeability modifies recirculation, alters instability transitions and produces flow regimes absent behind impermeable bodies. We have identified conditions that suppress unsteadiness, alongside more complex behaviour at intermediate permeability, and examined mechanisms through which permeable disks can experience enhanced drag. These contributions establish permeability as a design parameter for controlling aerodynamic response, with potential applications in passive flight and lightweight aerial devices.

Relevant Publications

• Bose, C., Bruce, C., & Viola, I. M. (2025). Porous plates at incidence. Theoretical and Computational Fluid Dynamics, 39(2), Article 19. https://doi.org/10.1007/s00162-025-00740-6
• Huang, D., Bose, C., Attili, A., & Viola, I. M. (2026a). Increasing Reynolds number promotes wake stabilisation behind a permeable disk [Manuscript submitted for publication].
• Huang, D., Bose, C., Attili, A., & Viola, I. M. (2026b). Wake dynamics of permeable disks across the transition from steady to chaotic flow. Journal of Fluid Mechanics, 1035, Article A15. https://doi.org/10.1017/jfm.2026.11514
• Huang, D., Gungor, A., Bose, C., Attili, A., & Viola, I. M. (2026). Drag enhancement on permeable disks: Mechanism, scaling and modelling [Manuscript submitted for publication].

We investigate how flow-driven structural motion can be converted into useful electrical energy. Combining experiments and numerical simulations, our work has demonstrated how wake interactions and simple geometric modifications influence the performance of piezoelectric energy harvesters. We have shown that appropriately positioned splitters can promote transitions from vortex-induced vibration to galloping and improve electrical output, while studies of flexible flappers reveal the importance of their position relative to upstream vortex shedding. These findings connect the underlying flow physics with practical choices for designing compact flow energy harvesters.

Relevant Publications

• Kumar, S. K., Bose, C., Ali, S. F., Sarkar, S., & Gupta, S. (2017). Investigations on a vortex induced vibration based energy harvester. Applied Physics Letters, 111(24), Article 243903. https://doi.org/10.1063/1.5001863
• Wang, J., Gu, S., Abdelkefi, A., & Bose, C. (2021). Enhancing piezoelectric energy harvesting from the flow-induced vibration of a circular cylinder using dual splitters. Smart Materials and Structures, 30(5), Article 05LT01. https://doi.org/10.1088/1361-665X/abefb5

We investigate how surface water waves interact with flexible and floating structures, and how this two-way coupling can be harnessed for marine renewable energy. Combining laboratory experiments with fluid–structure interaction simulations, we examine how incoming waves load and deform compliant structures, how structural stiffness, geometry and resonance shape the resulting motion, and how the structure in turn reflects, transmits and dissipates wave energy. Through a UK–France collaboration with PMMH (CNRS, Paris), we are exploring flexible wave energy converters that exploit passive deformation to extract energy efficiently across a range of wave conditions. These studies aim to establish design principles for robust, low-cost wave energy harvesters and wave-responsive coastal structures.

We investigate how small organisms generate thrust at the air–water interface, where surface tension and vortical flows jointly influence movement. Through collaborative experiments, flow measurements, physical models and simulations, we have demonstrated interfacial vortex recapture in the water-skating insect Microvelia americana. Its hind legs re-energise vortices produced by the middle legs, increasing propulsive forces through carefully coordinated motion. This work extends vortex-recapture principles to surface locomotion and identifies biological strategies that could inform the development of efficient microrobots operating on water.

Relevant Publications

• Rohilla, P., O’Neil, J. N., Singh, P., Ortega-Jimenez, V. M., Choi, D., Bose, C., & Bhamla, S. (2025). Interfacial vortex recapture enhances thrust in tiny water skaters [Preprint]. bioRxiv. https://doi.org/10.1101/2024.06.17.599397

We develop computational methods that make detailed simulations of moving bodies and interacting wakes more accessible. Our work combines immersed-boundary methods with overset grids to resolve complex geometries and body motion while concentrating computational effort where it is needed. We have contributed efficient grid-management and interpolation strategies, together with GPU and multi-GPU implementations, and validated these approaches across canonical and complex moving-body problems. These developments provide a scalable foundation for investigating bio-inspired flight, propeller flows and interactions between multiple moving bodies.

Relevant Publications

• Kumar, D., Sharma, S. D., Bose, C., & Roy, S. (2026). GPU optimized integration of immersed boundary method and overset mesh framework for moving boundary problems. Computer Methods in Applied Mechanics and Engineering, 461, Article 119241. https://doi.org/10.1016/j.cma.2026.119241
• Majumdar, D., Bose, C., & Sarkar, S. (2020). Capturing the dynamical transitions in the flow-field of a flapping foil using immersed boundary method. Journal of Fluids and Structures, 95, Article 102999. https://doi.org/10.1016/j.jfluidstructs.2020.102999

We are extending our research on flow through permeable media to investigate directional solidification and defect formation. This emerging theme focuses on how directional differences in permeability influence fluid transport through an evolving solid–liquid structure. Our aim is to connect flow behaviour with the mechanisms that generate material defects, bringing fluid-mechanical modelling into closer dialogue with solidification research. Through this work, we seek to develop a physical understanding that can support improved prediction and control of material quality during manufacturing.