Neil Bose

Bio: Neil Bose is an academic researcher from Memorial University of Newfoundland. The author has contributed to research in topics: Propeller & Propulsor. The author has an hindex of 22, co-authored 238 publications receiving 2119 citations. Previous affiliations of Neil Bose include St. John's University & University of Tasmania.

Propulsive performance from oscillating propulsors with spanwise flexibility

Abstract: The propulsive performance of oscillating foils with spanwise flexibility was studied using a time-domain panel method. The work was done to assess the effects of spanwise flexibility on the propulsive efficiency of these propulsors, especially those employed by relatively fast swimming marine animals. The method is valid for three-dimensional attached flows around the actual planforms found on these animals and was used in the study reported here to assess the performance of the flukes of an immature fin whale ( Balaenoptera physalus ). It is shown that passive spanwise flexibility reduces propulsive efficiency, but that propulsive efficiency of these planforms can be increased, over the value for an equivalent rigid foil, by careful control of the phase of the spanwise flexibility relative to other motion parameters.

Propulsion of a fin whale (Balaenoptera physalus): why the fin whale is a fast swimmer.

Abstract: Measurements of an immature fin whale (Balaenoptera physalus). which died as a result of entrapment in fishing gear near Frenchmans Cove. Newfoundland (47$^\circ$ $9'$ N. 55$^\circ$ $25'$ W), were made to obtain estimates of volume and surface area of the animal. Detailed measurements of the flukes, both planform and sections, were also obtained. A strip theory was developed to calculate the hydrodynamic performance of the whale's flukes as an oscillating propeller. This method is based on linear, two-dimensional, small-amplitude, unsteady hydrofoil theory with correction factors used to acount for the effects of finite span and finite amplitude motion. These correction factors were developed from theoretical results of large-amplitude heaving motion and unsteady lifting-surface theory. A model that makes an estimate of the effects of viscous flow on propeller performance was superimposed on the potential-flow results. This model estimates the drag of the hydrofoil sections by assuming that the drag is similar to that of a hydrofoil section in steady flow. The performance characteristics of the flukes of the fin whale were estimated by using this method. The effects of the different correction factors, and of the frictional drag of the fluke sections, are emphasized. Frictional effects in particular were found to reduce the hydrodynamic efficiency of the flukes significantly. The results are discussed and compared with the known characteristics of fin-whale swimming.

Measurements of the Bodies and Flukes of Several Cetacean Species

Abstract: Specimens of nine species of cetacean were obtained through an entrapment and stranding network. These were: harbour porpoise (Phocoena phocoena); white-sided dolphin (Lagenorhynchus acutus); white-beaked dolphin (Lagenorhynchus albirostris); common dolphin (Delphinus delphis); white whale (Delphinapterus leucas); Sowerby9s beaked whale (Mesoplodon bidens); minke whale (Balaenoptera acutorostrata); fin whale (Balaenoptera physalus); and sperm whale (Physeter macrocephalus). Measurements of length, body girths, fluke-planform offsets and fluke-section offsets are presented for these species. Values of body volume, mass, wetted-surface area, prismatic and volumetric coefficients, fluke area, aspect ratio and sweep angles were estimated from these measurements. Parameters derived from these measurements lay within narrow ranges of values for all species. Variation over these ranges may indicate a correlation between species and their relative swimming performance.

The Environmental Protection Agency

Abstract: The Environmental Protection Agency (EPA) provides access to information on a variety of topics related to the environment and strives to inform citizens of health risks. The EPA also has an extensive library network that consists of 26 libraries throughout the United States, which provide access to a plethora of information to EPA employees, scientists, and researchers. The EPA implemented a reorganization project to digitize their materials so they would be more accessible to a wider range of users, but this plan was drastically accelerated when the EPA was threatened with a budget cut. It chose to close and reduce the hours and services of some of their libraries. As a result, the agency was accused of denying users the “right to know” by making information unavailable, not providing an adequate strategic plan, and discarding vital materials. This case study explores the background of the digitization project, the practices implemented, and the critiques of the project.

Review of fish swimming modes for aquatic locomotion

Abstract: Several physico-mechanical designs evolved in fish are currently inspiring robotic devices for propulsion and maneuvering purposes in underwater vehicles. Considering the potential benefits involved, this paper presents an overview of the swimming mechanisms employed by fish. The motivation is to provide a relevant and useful introduction to the existing literature for engineers with an interest in the emerging area of aquatic biomechanisms. The fish swimming types are presented, following the well-established classification scheme and nomenclature originally proposed by Breder. Fish swim either by body and/or caudal fin (BCF) movements or using median and/or paired fin (MPF) propulsion. The latter is generally employed at slow speeds, offering greater maneuverability and better propulsive efficiency, while BCF movements can achieve greater thrust and accelerations. For both BCF and MPF locomotion, specific swimming modes are identified, based on the propulsor and the type of movements (oscillatory or undulatory) employed for thrust generation. Along with general descriptions and kinematic data, the analytical approaches developed to study each swimming mode are also introduced. Particular reference is made to lunate tail propulsion, undulating fins, and labriform (oscillatory pectoral fin) swimming mechanisms, identified as having the greatest potential for exploitation in artificial systems.

Oscillating foils of high propulsive efficiency

Abstract: Thrust-producing harmonically oscillating foils are studied through force and power measurements, as well as visualization data, to classify the principal characteristics of the flow around and in the wake of the foil. Visualization data are obtained using digital particle image velocimetry at Reynolds number 1100, and force and power data are measured at Reynolds number 40 000. The experimental results are compared with theoretical predictions of linear and nonlinear inviscid theory and it is found that agreement between theory and experiment is good over a certain parametric range, when the wake consists of an array of alternating vortices and either very weak or no leading-edge vortices form. High propulsive efficiency, as high as 87%, is measured experimentally under conditions of optimal wake formation. Visualization results elucidate the basic mechanisms involved and show that conditions of high efficiency are associated with the formation on alternating sides of the foil of a moderately strong leading-edge vortex per half-cycle, which is convected downstream and interacts with trailing-edge vorticity, resulting eventually in the formation of a reverse Karman street. The phase angle between transverse oscillation and angular motion is the critical parameter affecting the interaction of leading-edge and trailing-edge vorticity, as well as the efficiency of propulsion.