Propulsion By Sinusoidal Locomotion: A Motion Inspired By Caenorhabditis Elegans

OF THE THESIS Propulsion by Sinusoidal Locomotion: a Motion Inspired by Caenorhabditis elegans by Xialing Ulrich Doctor of Science in Mechanical Engineering Washington University in St. Louis, 2012 Research Advisor: Professor David Peters Sinusoidal locomotion is commonly seen in snakes, fish, nematodes, or even the wings of some birds and insects. This doctoral thesis presents the study of sinusoidal locomotion of the nematode C. elegans in experiments and the application of the state-space airloads theory to the theoretical forces of sinusoidal motion. An original MATLAB program has been developed to analyze the video records of C. elegans ’ movement in different fluids, including Newtonian and non-Newtonian fluids. The experimental and numerical studies of swimming C. elegans has revealed three conclusions. First, though the amplitude and wavelength are varying with time, the motion of swimming C. elegans can still be viewed as sinusoidal locomotion with slips. The average normalized wavelength is a conserved character of the locomotion for both Newtonian and non-Newtonian fluids. Second, fluid viscosity affects the frequency but not the moving speed of C. elegans, while fluid elasticity affects the moving speed but not the frequency. Third, by the resistive force theory, for more elastic fluids the ratio of resistive coefficients K = Cn/Cl becomes smaller.