Fish are thought to adjust their tail stiffness to swim efficiently over a wide range of speeds, but how they tune stiffness has been a mystery. We derived a model that combines fluid …
Animals and bio-inspired robots can swim/fly faster near solid surfaces like the seafloor. In the past, researchers had quantified how strong these effects were for two-dimensional airfoils. We studied how …
We developed a model that estimates how thrust and efficiency change as a pitching hydrofoil gets closer to a planar boundary. Our model predicts that the modified forces are caused …
The dorsal and anal fins of fish interact with the tail fins to produce higher thrust and efficiency. We focused on thin elongated dorsal fins, like those of jackfish. We …
Fish flap their tails asymmetrically to maneuver around obstacles. In contrast, classic fish tail models assume symmetric motions in a uniform flow. We tested how well these classic models work …
Fish and birds experience different forces when they swim/fly near a flat surface (e.g. seabed, solid ground, still lake). We discovered that the vertical forces they feel switch from negative …
Pilots need complex instruments and training to safely fly through gusts when their vision is deprived. In contrast, birds fly reliably over open water and at night, despite being more …
Building on our previous work on 2-D pitching airfoils, we explored how forces and torques scale for 3-D pitching airfoils. The terms we added to existing theories were inspired by …
Modeling the forces and torques on 2-D pitching airfoils is critical for understanding the locomotion of fish and birds. Traditional linear theories can predict some of the forces, but break …
Existing studies of fish and bird locomotion typically assume the fins/wings oscillate sinusoidally. We explored what happens when the oscillations range from triangle waves to square waves. Triangle waves behave …
We worked with the Jacobs Engineering Group to build a wind tunnel specifically designed for studying birds. The test section is about 1 m wide and can reach speeds of …
Estimating lift from the flow around flapping wings is critical for studying bird flight. To test existing lift theories, we measured the flow around a parrotlet’s wing as it flew …
Simplified geometries can be used to isolate the effects of flexibility in swimming fish. Here we used an oscillating flexible rectangular panel to explore how efficiency is affected by frequency, …
When fish swim in a school, they interact hydrodynamically with one another. We explored these interactions by testing two rigid pitching airfoils side-by-side in a water channel. We found that …
We extended our work on rigid airfoils and discovered that flexible panels also produce more thrust near a solid boundary. This time, we checked swimming speed directly and confirmed that …
Airplanes gliding near the ground experience experience a boost in lift. We discovered that this boost extends to unsteady lift forces, such as those governing thrust production in fish. Fish …
Simplified geometries can be used to isolate the effects of flexibility in swimming fish. Here we used an oscillating flexible rectangular panel to explore how efficiency scales with panel stiffness …