Caltech Library System

About | Browse | Search | Caltech Student Instructions

Type of Document	Dissertation
Author	Dabiri, John Oluseun
URN	etd-04112005-151435
Persistent URL	http://resolver.caltech.edu/CaltechETD:etd-04112005-151435
Title	Unsteady fluid mechanics of starting-flow vortex generators with time-dependent boundary conditions
Degree	PhD
Option	Bioengineering
Advisory Committee	Advisor Name Title Morteza Gharib Committee Chair Anthony Leonard Committee Member Dale Ian Pullin Committee Member Joel Wakeman Burdick Committee Member John F. Brady Committee Member Michael H. Dickinson Committee Member
Keywords	cardiovascular flows locomotion vortex dynamics biological flows
Date of Defense	2005-04-08
Availability	unrestricted
Abstract Nature has repeatedly converged on the use of starting flows for mass, momentum, and energy transport. The vortex loops that form during flow initiation have been reproduced in the laboratory and have been shown to make a proportionally larger contribution to fluid transport than an equivalent steady jet. However, physical processes limit growth of the vortex loops, suggesting that these flows may be amenable to optimization. Although it has been speculated that optimal vortex formation might occur naturally in biological systems, previous efforts to quantify the biological mechanisms of vortex formation have been inconclusive. In addition, the unsteady fluid dynamical effects associated with starting flow vortex generators are poorly understood. This thesis describes a combination of new experimental techniques and in vivo animal measurements that determine the effects of fluid-structure interactions on vortex formation by starting flow propulsors. Results indicate that vortex formation across various biological systems is manipulated by these kinematics in order to maximize thrust and/or propulsive efficiency. An emphasis on observed vortex dynamics and transient boundary conditions facilitates quantitative comparisons across fluid transport schemes, irrespective of their individual biological functions and physical scales. The primary contributions of this thesis are the achievement of quantitative measures of unsteady vortex dynamics via fluid entrainment and added-mass effects, and the development of a robust framework to facilitate the discovery of general design principles for effective fluid transport in engineering technologies and biological therapies. The utility of this new research paradigm is demonstrated through a variety of examples.
Files	Filename       Size       Approximate Download Time (Hours:Minutes:Seconds)     28.8 Modem   56K Modem   ISDN (64 Kb)   ISDN (128 Kb)   Higher-speed Access    jodabiri_thesis.pdf 3.23 Mb 00:14:57 00:07:41 00:06:43 00:03:21 00:00:17