Date of Award


Document Type

Open Access Dissertation

Degree Name

Doctor of Philosophy in Mechanical Engineering-Engineering Mechanics (PhD)

Administrative Home Department

Department of Mechanical Engineering-Engineering Mechanics

Advisor 1

Hassan Masoud

Committee Member 1

Gordon Parker

Committee Member 2

Sajjad Bigham

Committee Member 3

Raymond Shaw


Many animals in nature travel in groups either for protection, survival, or endurance. Among these, fish do so under the burden of hydrodynamic loads, which incites questions as to the significance of the multi-body fluid-mediated interactions that facilitate collective swimming. We study such interactions in the idealized setting of a rotational array of robotic fish whose tails undergo a prescribed flapping motion, but whose swimming speed is determined as a natural result of the hydrodynamic effects. Specifically, we examine how the measured collective speed of the swimmers varies with the imposed frequency and amplitude of their tail flapping, and with the phase difference between the tail motions of neighboring robots in the array. We also consider the effects of the spacing between the fish and the flexibility of their tail on the group performance of the fish ensemble. To visualize the flow field while the swimmers are in motion, we implement a camera system to track neutrally buoyant florescent particles suspended in the water surrounding the fish. This three-dimensional particle tracking velocimetry technique allows us to capture the trajectory of the seeding particles and, thereby, derive the velocity and vorticity fields around the interacting fish. By exploring a wide parameter space, we identify the conditions under which multi-body hydrodynamics interactions enhance or impede the swimming performance of a robotic fish array relative to the performance of an identical solo swimmer. Applications that can directly benefit from the findings of our investigation include the design and control of robotic fish swarms.