

@mastersthesis {6586,
	title = {Flow, turbulence, and dispersion above and within the roughness sublayer: {Field} observations and laboratory modeling},
	year = {2009},
	note = {3357001},
	school = {University of California, Riverside},
	type = {phdPh.{D}.},
	address = {Ann Arbor},
	abstract = {Most human activities take place in the atmospheric surface layer (ASL), approximately the bottom one tenth of the atmospheric boundary layer. In the urban ASL, the roughness sublayer (RSL) where conventional ASL scaling theories are challenged due to increased urban roughness and horizontal inhomogeneity, becomes significantly larger and more important than its rural counterpart. Modeling air quality and toxic release in urban environments requires improved understanding of flow, turbulence and dispersion above and within the RSL. This dissertation is motivated by this need, and three individual studies are discussed regarding this issue through field observations and laboratory modeling. The first study utilizes experimental data collected in 2002 over an open field in Hanford, Washington, to investigate the turbulent kinetic energy (TKE) budget above the RSL. Contrary to the traditional similarity theory, the shear production, the buoyancy production and the dissipation rate of TKE are found to be imbalanced due to non-zero vertical transport that occurs over all stabilities. Motivated by this observation, modified parameterizations of the dissipation rate and the turbulent transport are proposed, and resulting predictions are in good agreement with experimental data. The second study aims to gain better understanding of flows through urban-like arrays of obstacles within the RSL utilizing laboratory water channel experiments. A novel flow feature, lateral channeling, observed and quantitatively measured by Particle Image Velocimetry (PIV), within regular 3 x 3 and 5 x 5 arrays of cubes is reported. The newly identified mean flow pattern may account for the initial plume spread within an array of buildings. The third study utilizes the laboratory PIV-PLIF (Planar Laser Induced Florescence) combo technique to investigate urban dispersion of buoyant sources from a distributed generation (DG) unit to complement the field study conducted in July 2008 in Palm Springs, California. Five scaling laws, which determine laboratory setup from field parameters and scale PLIF data back to field scales, are validated by field data and variations of laboratory experiments. The plume rise, plume spreads, ground level concentration of scalar, and plume structure are then determined from scaled PLIF data.},
	keywords = {0548:Mechanical engineering, Applied sciences, Dispersion, Lateral channeling, Local imbalance of TKE, Mechanical engineering, PIV, Roughness sublayer, Turbulence},
	url = {http://search.proquest.com/docview/304857628?accountid=14270},
	author = {Li, Xiangyi}
}
