Scientists detail jumping physics of tiny fish
Scientists detail jumping physics of tiny fish lead image
The tiny archer fish (Toxotes microlepis) has evolved to leap from the water, achieving accelerations several times the pull of gravity. Exactly how these little fish accelerate from a stationary position has remained a mystery. For the first time, scientists have modeled this behavior to better understand the physics behind the fish’s powerful acrobatic feats.
Building on previous experimental work using live fish, Khosronejad et al. developed numerical simulations to further understand the flow dynamics behind the fish’s leaping ability.
“Biologists have been trying to understand archer fish behavior for well over a century,” said author Fotis Sotiropoulos. “Our work contributes to assessing the role of jumping as a competitive foraging strategy.”
Using the fish’s complex body shape and movements captured with high-speed imaging, the team constructed a virtual archer fish. This fish was used as input to a high-fidelity, two-phase flow, large-eddy simulation of the flow patterns in the water, at the water-air interface and in the air. The simulations matched the experimental data and helped explain the mechanism behind the striking three-dimensional patterns of the eddies shed by the fish body and fins while in the air.
“The simulations have helped us understand for the first time how the fish generates and leverages complex vortex structures to stabilize and control its trajectory as it approaches its prey,” said Sotiropoulos.
By performing numerical experiments using a fish with and without pectoral fins, they have shown that pectoral fins contribute considerably to thrust production and overall jumping performance.
Sotiropoulos believes this work could one day lead to the development of bio-inspired autonomous underwater vehicles that are agile enough to operate across the air-water interface.
Source: “Water exit dynamics of jumping archer fish: Integrating two-phase flow large-eddy simulation with experimental measurements,” by Ali Khosronejad, Leah Mendelson, Alexandra H. Techet, Seokkoo Kang, Dionysios Angelidis, and Fotis Sotiropoulos, Physics of Fluids (2020). The article can be accessed at https://doi.org/10.1063/1.5130886 .
