Understanding animal locomotion requires modeling the interaction of the organism with its environment. Locomotion within granular media like sand, soil, and debris that display both solid and fluid-like behavior in response to stress is less studied than locomotion within fluids or on solid ground. To begin to reveal the secrets of movement in sand, I developed models to explain the subsurface locomotion of the sand-swimming sandfish lizard. I developed a resistive force theory (RFT) with empirical force laws to explain the swimming speed observed in animal experiments. By varying the amplitude of the undulation in the RFT, I found that the range of amplitude used by the animal predicted the optimal swimming speed. I developed a numerical model of the sandfish coupled to a discrete element method simulation of the granular medium to test assumptions in the RFT and to study more detailed mechanics of sand-swimming. Inspired by the shovel-shaped head of the sandfish lizard, I used the simulation to study lift forces in granular media: I found that when a submerged intruder moved at a constant speed within a granular medium it experienced a lift force whose sign and magnitude depended on the intruder shape. The principles learned from the models guided the development of a biologically inspired robot that swam within granular media with similar performance to the lizard.
Identifer | oai:union.ndltd.org:GATECH/oai:smartech.gatech.edu:1853/45880 |
Date | 14 November 2011 |
Creators | Ding, Yang |
Publisher | Georgia Institute of Technology |
Source Sets | Georgia Tech Electronic Thesis and Dissertation Archive |
Detected Language | English |
Type | Dissertation |
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