Siyang Hao

Siyang Hao

Research Associate at the University of Virginia | Fluid Mechanics & Bio-inspired Robotics

Publications

You can also find my articles on my Google Scholar profile.

Surfing on Vortices: Bird Flight Responses to an Unsteady Vortex Wake

Published in Experiments in Fluids, 2026

Wind tunnel experiments on European Starlings flying behind an oscillating airfoil show that birds actively engage with a structured vortex wake, adjusting their trajectories and phase-aligning their wingbeats with the periodic wake.

Recommended citation: S. Hao, N. Medina, M. Islam, R. Gissler, T. Hedrick, A. Gerson, K. Breuer. Surfing on vortices: bird flight responses to an unsteady vortex wake [J]. Experiments in Fluids, 2026, 67(11): 162. https://doi.org/10.1007/s00348-026-04292-1

Flapping Frequency, Amplitude, and Organization: Associations Between Accelerometer Data and Flight Energy Costs During Solo and Small Group Flight of European Starlings

Published in Integrative and Comparative Biology, 2026

Accelerometer and metabolic data from European Starlings show that, in solo flight, continuous low-effort flapping reduced energy costs compared with bursts of high-effort flapping, while low-cost birds in small groups used slow, organized burst-coast rhythms. For followers, the organization of the leader’s flapping was more closely associated with the follower’s energy cost than any metric recorded from the follower itself.

Recommended citation: T. L. Hedrick, S. I. Friman, C. R. Elowe, S. Hao, A. R. Gerson, K. S. Breuer. Flapping frequency, amplitude, and organization: associations between accelerometer data and flight energy costs during solo and small group flight of European Starlings [J]. Integrative and Comparative Biology, 2026, 66: icag124. https://doi.org/10.1093/icb/icag124

Proportional Control of Aerodynamic Forces Using an Active Gurney Flap on a Wind Turbine Blade Section

Published in Wind Energy, 2025

Real-time, proportional deployment of an active Gurney flap near the trailing edge of a wind turbine blade section is used to modulate lift and pitching moment, with the aerodynamic response scaling with deployment angle.

Recommended citation: S. Hao, A. Koh-Bell, R. Irani, J. Kirsch-Posner, K. Breuer. Proportional Control of Aerodynamic Forces Using an Active Gurney Flap on a Wind Turbine Blade Section [J]. Wind Energy, 2025, 28(10): e70056. https://doi.org/10.1002/we.70056

Upstroke Wing Clapping in Bats and Bat-Inspired Robots Offers Efficient Lift Generation

Published in Journal of the Royal Society Interface, 2025

Experiments with bats and a bat-inspired flapping robot show that clapping the wings during the upstroke enhances lift generation while improving power economy.

Recommended citation: X. Fan, A. Bortoni, S. Hao, S. Swartz, K. Breuer. Upstroke wing clapping in bats and bat-inspired robots offers efficient lift generation [J]. Journal of the Royal Society Interface, 2025, 22(223): 20240590. https://doi.org/10.1098/rsif.2024.0590

It Pays to Follow the Leader: Metabolic Cost of Flight is Lower for Trailing Birds in Small Groups

Published in Proceedings of the National Academy of Sciences, 2024

Combining wind tunnel flight tests, kinematic tracking and metabolic measurements on European Starlings to quantify the energetic benefit of trailing positions in small flocks.

Recommended citation: S. I. Friman, C. R. Elowe, S. Hao, L. Mendez, R. Ayala, I. Brown, C. Hagood, Y. Hedlund, D. Jackson, J. Killi, G. Orfanides, E. Ozcan, J. Ramirez, A. R. Gerson, K. S. Breuer, T. L. Hedrick. It pays to follow the leader: Metabolic cost of flight is lower for trailing birds in small groups [J]. PNAS, 2024, 121(26): e2319971121. https://doi.org/10.1073/pnas.2319971121

Proportional Control of Aerodynamic Forces using an Active Gurney Flap on a Wind Turbine Blade Section

Published in AIAA SCITECH 2023 Forum, 2023

Wind tunnel experiments over Re = 160,000–414,000 show that proportional deployment of an active Gurney flap improves lift and pitching moment with an increased lift-to-drag ratio, with the maximum effect near 70 degrees of deployment.

Recommended citation: S. Hao, A. Koh-Bell, R. Irani, J. Kirsch-Posner, K. Breuer. Proportional Control of Aerodynamic Forces using an Active Gurney Flap on a Wind Turbine Blade Section [C]. AIAA SCITECH 2023 Forum, AIAA 2023-0459. https://doi.org/10.2514/6.2023-0459