This research will investigate fundamental problems in fluid-structure interactions motivated by the development of an efficient and maneuverable submersible. This submersible employs a fish-like flexible tail driven by a conveyed fluid jet; the combination of the jet's thrust and that of the oscillating tail synergistically propels and maneuvers the submersible. Two disconnected bodies of fluid-structure interaction literature will be merged in this research - the study of oscillatory fish-like propulsion and the study of fluttering fluid-conveying pipes. The fluid-conveying pipe literature will be extended toward conditions that exist in fish-like swimming: external flow, spatially-variable tail planforms, large deformations, and fast accelerations and large rotations. Furthermore, acceleration and rotation of the submersible will be accomplished by varying the conveyed fluid velocity; an area, which requires additional theoretical development. Euler-Bernoulli beam theory and the theory of elastica will be used to model spatially-varying beams conveying fluid with time-dependent velocity. These theoretical investigations will be complemented by numerical simulations and a hardware platform for experimental verification.
This fish-like submersible uses a novel mechanism for propulsion which requires investigation of a flexible tail subjected to significant accelerations and fluid forces. The submersible has many potential applications; since the surrounding water is pulled into the hull during normal operation, it is an ideal candidate for environmental monitoring, chemical sensing and water cleanup operations. The methods developed in this research will also apply to other emergent problems in fluid structure interactions, such as vibration control of large wind turbine blades and better design of ornithopters through improved understanding of bat and insect flight. In humans, deflection of a flexible member in the airway causes snoring and sleep apnea - better understanding of fluid loading on flexible structures could lead to improved therapy and surgical treatments.
