Wingtip vortices are an important problem in aerodynamic and hydrodynamic engineering because of their contribution to induced drag, tip cavitation, and wake turbulence. These effects decrease equipment efficiency and lifespan, which increases application costs. Biology provides an inspiring solution to this problem in avian flight through the spreading of primary feathers. Previous studies have shown increased lift to drag ratio and efficiency of wings and propeller blades through modified wingtip geometry. The goal of this project is to optimize the tip geometry (primary feather angle) of a test wing for minimal tip vortex strength using genetic algorithms to mimic natural design evolution. Ultrasonic transducers are used to measure the wing tip vortex circulation in wind tunnel tests for each candidate design. Although neither angle of attack series converged completely, there was partial convergence in each. Due to the fluctuations in the low angle of attack tests, the parent selection algorithm was altered for the high angle of attack series, which resulted in improved convergence trends. A genetic algorithm that used uniform crossover breeding, a 20% mutation rate, and roulette wheel parent selection methods was used to generate an improved tip geometry at a low angle of attack of 6° and a freestream velocity of 15.25 m/s over the course of 17 generations. This improved design consisted of three key features, a staggered leading edge, a drastic mid-section vertical separation, and an upswept trailing edge. A second algorithm, which employed uniform crossover, a 20% mutation rate, and an elitist selection roulette parent selection, provided an improved tip geometry for a 12° angle of attack at a freestream velocity of 11.5 m/s. This improved design consisted of three key features, a downswept leading edge, a drastic mid-section vertical separation, and an upturned trailing edge. Both results showed that the wing tip vortex strength can be reduced by approximately 20% by manipulating tip geometry and that the trailing edge traits produce the most prominent effects on vortex strength.

Intakes are inlet structures where fluid is accelerated to a certain flow velocity to provide required amount of water into a hydraulic system. Intake size and geometry affects the formation of flow patterns, which can be influential for hydraulic performance of the whole system. An experimental study is conducted by measuring velocity field in the hydraulic model of the head pond of a hydropower plant to investigate vortex formation. Vortex strength based on potential flow theory is calculated from the measured velocity field. It was shown that vortex strength increases with the submergence Froude number. The free surface flow in the head pond is simulated using Flow-3D software. Vortex strength calculations are repeated using the computational velocity distributions and compared to experimentally obtained values. Similar computations were carried on with some idealized pond geometries such as rectangular and circular.

A planing catamaran is a high-powered, twin-hull water craft that develops the lift which supports its weight, primarily through hydrodynamic water pressure. Presently, there is increasing demand to further develop the catamaran's planing and seakeeping characteristics so that it is more effectively applied in today's modern military and pleasure craft, and offshore industry supply vessels. Over the course of the past ten years, Vorus (1994,1996,1998,2000) has systematically conducted a series of research works on planing craft hydrodynamics. Based on Vorus' planing monohull theory, he has developed and implemented a first order nonlinear model for planing catamarans, embodied in the computer code CatSea. This model is currently applied in planing catamaran design. However, due to the greater complexity of the catamaran flow physics relative to the monohull, Vorus's (first order) catamaran model implemented some important approximations and simplifications which were not considered necessary in the monohull work. The research of this thesis is for relieving the initially implemented approximations in Vorus's first order planing catamaran theory, and further developing and extending the theory and application beyond that currently in use in CatSea. This has been achieved through a detailed theoretical analysis, algorithm development, and careful coding. The research result is a new, complete second order nonlinear hydrodynamic theory for planing catamarans. A detailed numerical comparison of the Vorus's first order nonlinear theory and the second order nonlinear theory developed here is carried out. The second order nonlinear theory and algorithms have been incorporated into a new catamaran design code (NewCat). A detailed mathematical formulation of the base first order CatSea theory, followed by the extended second order theory, is completely documented in this thesis.