Archer fish are capable of accurately jumping for aerial prey from a stationary aiming position directly below the water’s surface. This jumping behavior may provide a bioinspired strategy for water-exit in underwater vehicles, especially in sensitive environments where other thrusters (e.g., high-pressure water jets) may be too disruptive. However, any engineered implementation of this behavior relies on the ability to simplify, replicate, and optimize archer fish-inspired propulsion using a mechanical system. In particular, flapping flexible plates and hydrofoils are commonly-used simplified mechanical models of fish locomotion. This project aims to use these models to understand why the archer fish changes the timing and size of each tailbeat as it leaves the water and how to optimally execute similar kinematic variations.
We use a combination of experimental and computational models to determine how changing the amplitude and timing of each propulsive “tailbeat” affects cumulative propulsion during water-exit. Is it better to execute faster, smaller-amplitude motions or larger, sweeping ones? How does the optimal motion vary with the size and flexibility of the actuator? Can we time each motion such that a beneficial interaction with the wake of the previous tailbeat is achieved? At what point during water-exit does force production reach diminishing returns, where so little of the plate or foil is underwater that additional “tailbeats” do not significantly contribute thrust?
Experimental efforts to answer these questions include designing and prototyping mechanisms to replicate the kinematics of jumping fish and analyzing the forces and flow patterns produced by these mechanical models using high speed imaging, dye visualization, six axis force sensing, and particle image velocimetry.
Computational efforts to answer these questions combine Computational Fluid Dynamics simulations (using open-source software) and mathematical modeling. In particular, we focus on using simulations to inform experiment design and on modeling the stability of a partially-submerged, flapping-actuated inverted pendulum (think dolphin tailstand).
Research will take place during the Fall and Spring semesters for academic credit. Paid summer students will be recruited from within the research group contingent on funding.
Essay Prompt (~paragraph length): Why are you interested in working on this research project? What will you bring to the project and what do you hope to learn? Please also submit the names of two HMC professors as references who can comment on your work habits.
Students will join a collaborative team working at the interface of biomechanics, fluid mechanics, mechanical design, and computer vision.
The Flow Imaging Lab at (Harvey) Mudd (FILM), directed by Prof. Leah Mendelson, experimentally studies biological and bioinspired fluid mechanics. We mechanically recreate swimming behaviors seen in nature to identify new strategies for underwater vehicle propulsion. The group also works on low-cost tools for flow field measurements. Research projects in FILM frequently involve mechanical design and mechatronics, high-speed imaging, and particle image velocimetry, an experimental technique for measuring fluid velocities by filming the motion of tracer particles suspended in the flow. We frequently use image processing, computer vision, and computational photography to understand the behavior of a fluid flow.