Date of Award

4-2020

Degree Name

Doctor of Philosophy

Department

Engineering and Applied Sciences

First Advisor

Dr. Dewei Qi

Second Advisor

Dr. James R. Springstead

Third Advisor

Dr. Qingliu Wu

Fourth Advisor

Dr. Chris Cho

Keywords

Fish-like swimming, computer simulation, lattice Boltzmann method, lattice spring model, immersed boundary method

Abstract

A novel muscle driven method is developed to mimic contracting and expanding of muscles, in a fish-like swimming body, which cause its body flapping in the transversal direction and create thrust force to push its body to cruise in the longitudinal direction. The muscle deformation is realized by using the RATTLE constraint algorithm. The turbulent fluids are treated by a multi-relaxation time lattice Boltzmann method with a large eddy simulation. The fish body is dealt with a lattice spring model and interactions between fluids and solid structures are handled by a direct-forcing immersed boundary method. Validations are conducted by comparing our simulation results with the existing experimental and theoretical results. Subsequently, the frequency, amplitude, and wave length of muscle distortion are systematically varied at different levels and their effects on flapping and cruising motion are studied. It is revealed that the flapping and cruising Reynolds numbers increase linearly as the distortion frequency increases and they also increase as the distortion amplitude increases. However, the increasing rate is smaller in a larger amplitude range than in a smaller amplitude range. It is also demonstrated that the flapping and cruising Reynolds numbers weakly depend on the wave length. Furthermore, the effect of flexibility and inertia of fish tail on performance of the fish-like swimming is studied base on this muscle driven swimming model. The results and discussions reveal the mechanisms of the self-propelled flexible structure.

Access Setting

Dissertation-Campus Only

Restricted to Campus until

4-30-2021

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