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Turbulence is a significant factor in near-road air quality, as it affects the initial dilution, dispersion, and the ultimate fate of pollutants. This study used computational fluid dynamics simulations to model the turbulent kinetic energy (TKE) on roadways, focusing on vehicle-induced turbulence. TKE was shown to decay with different power-law exponents depending on vehicle types; vehicle speeds and winds affect TKE; and thermal impacts are negligible. It was found that TKE is superimposed for vehicles in series; TKE does not dissipate far laterally, and the side-by-side interactions are not significant regardless of the directions. Thus, TKE for different traffic compositions may be expressed as a sum of the contribution from each type of vehicle. Insights gained in this study may enable the quantification of TKE for various traffic scenarios based on TKE values of single vehicle of different types, and simplify the TKE estimations in regional air quality models.

Turbulence is a significant factor in near-road air quality, as it affects the initial dilution, dispersion, and the ultimate fate of pollutants. This study used computational fluid dynamics simulations to model the turbulent kinetic energy (TKE) on roadways, focusing on vehicle-induced turbulence. TKE was shown to decay with different power-law exponents depending on vehicle types; vehicle speeds and winds affect TKE; and thermal impacts are negligible. It was found that TKE is superimposed for vehicles in series; TKE does not dissipate far laterally, and the side-by-side interactions are not significant regardless of the directions. Thus, TKE for different traffic compositions may be expressed as a sum of the contribution from each type of vehicle. Insights gained in this study may enable the quantification of TKE for various traffic scenarios based on TKE values of single vehicle of different types, and simplify the TKE estimations in regional air quality models.

This thesis evaluates performance of a non-mechanical conduit valve that was designed for the purpose of this research. The motivation came from the need for a cooling system of portable computers (e.g. laptops and netbooks). As the technology of micro-processors in portable computers advances, they will generate more heat, requiring a more effective and efficient way to cool the system. Based on this fact, a new method of heat dissipation using a single-phase liquid (i.e. water) instead of air was examined. This potentially allowed 80 times more heat dissipation, which translates to better and faster computers for the near future. In designing a single-phase-liquid micro-scale cooling system, various pump mechanisms and their functionalities were considered. It was concluded that a diaphragm pump design is the most effective candidate for this cooling system. The essential component when designing a diaphragm pump is a valve; however, the main issues in selecting a valve are its mechanics and required maintenance. Thus, the non-mechanical valvular conduit, which uses no moving mechanism, was studied through a combination of numerical/computational and experimental methods. The non-mechanical valvular conduit is a micro-channel with a complex geometry; hence, this conduit uses the principle of pressure resistance in the channel flow such that the flow is uni-directional. Through the numerical study, the valvular conduit design’s geometric dimensions were optimized. Then numerical simulations of the pumping/oscillating sequence of the valvular conduit were conducted to examine the effectiveness of the valve when placed in use for a diaphragm pump. It was found that the non-mechanical valve was 38 % more effective in the favorable direction than the opposite direction. As for the necessary heat dissipation, this conduit design demonstrates a great potential to dissipate the thermal design power (TDP) of Intel Pentium D processor (i.e. 130 [W]). During the experiments, the non-mechanical valve confirmed the numerical results. The experimental results also demonstrated that the favorable direction flow produced 244 % less pressure resistance than the opposite direction flow. It was concluded that the non-mechanical valvular conduit can be an effective application for diaphragm pumps in macro and micro-scale without any possibility of obstructing a mechanism.

Extensive research has been conducted in the area of journal bearings over many years for various operating conditions and geometry, effects of different types of lubricants (oil and water), different numbers (zero, one and three) and positions of grooves and the flow of lubricant between the shaft and bearing. One area of research has been developing methods to minimize the experimental time and cost of predicting the performance of journal bearings operating over a wide variety of conditions. This has led to numerical methods being developed and utilised for this purpose. Numerical methods are an important foundation for the development of Computational Fluid Dynamics (CFD). CFD method has proved to be a very useful tool in this research field. This project uses a CFD (specifically FLUENT) approach to simulate the fluid flow in a water lubricated journal bearing with equal spaced axial grooves. Water is fed into the bearing from one end. The lubricant is subjected to a velocity induced flow, as the shaft rotates and a pressure induced flow, as the water is pumped from one end of the bearing to the other. CFD software is used to simulate the fluid flow phenomenon that occurs during the process. Different parameters such as eccentricity ratio, number of grooves and groove orientation to the load line were examined. Lubricant pressure and velocity profiles were obtained and compared with available theoretical and experimental results. Two dimensional studies showed that the predicted maximum pressure and load carrying capacity from CFD were similar to the results from theoretical calculations. A small percentage difference (1.78% - 3.76%) between experimental and theoretical results was found. The pressure distribution in the lubricant shows that grooves decrease the pressure and load carrying capacity of the bearing. Swirl or turbulence does occur in the groove is affected by the viscosity of the lubricant. Three dimensional studies show that the pressure drops linearly from one end of the bearing to the other for no groove, concentric and three grooves cases. As the eccentricity increases, for one groove cases, the shape of the pressure profile changes to parabolic shape at positive region while the other pressure profiles drop linearly. The magnitude of the velocity it the bearing gap increased from 0.8 m/s to about 2.9 m/s when the shaft speed increased from zero to 5.5 m/s for a concentric and no groove case, similar changes were noted for all other cases. An interesting observation occurs when implementing the pressure profiles along the bearing. At cases such as zero and one groove condition and e = 0.4 and 0.6, lubricant flow back is observed at both inlet and outlet i.e. at certain area of the inlet, lubricant flowed out of the bearing against the supply pressure, a similar situation occurred at the exit of the bearing.

Thesis (Ph. D.)--Washington State University, December 2008. / Title from PDF title page (viewed on Apr. 13, 2009). "School of Mechanical and Materials Engineering." Includes bibliographical references (p. 101-105).

Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 145-148). Also available on the World Wide Web.

Thesis (Ph. D., Mechanical Engineering)--University of Idaho, June 2009. / Major professor: Akira Tokuhiro. Includes bibliographical references. Also available online (PDF file) by subscription or by purchasing the individual file.

Thesis (Ph.D)--Aerospace Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Mavris, Dimitri; Committee Member: Alley, Nicholas; Committee Member: Lakshmi, Sankar; Committee Member: Sriram, Rallabhandi; Committee Member: Stephen, Ruffin. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (M.S.)--Brigham Young University. Dept. of Mechanical Engineering, 2008. / Includes bibliographical references (p. 79-82).