In this thesis, wall-resolved and wall-modeled large-eddy simulation (LES) have been employed to investigate turbulent flow and dispersion around a single and a group of wall-mounted bluff bodies which are partially and fully submerged in developing boundary layers, respectively. The dispersion is caused by a continuous release of a passive scalar from a ground-level point source located within the matrix of obstacles. The results have been validated through comparisons against the available experimental measurement data. Thorough physical analysis including investigation of the spatial evolution and temporal cascades of the kinetic and scalar energies, flow structures and their influences on dispersion of the concentration plume in the context of highly disturbed flows, and study of turbulence statistics for the flow and concentration fields have been performed to provide deeper insights into turbulent flow and dispersion in domains with complex geometries. An in-house code based on FORTRAN programming language, parallelized with MPI libraries has been developed, modified and optimized for conducting the simulations. The simulations have been conducted on public-domain supercomputers ofWest-Grid, specifically Orcinus and Grex, and also the local 256-core cluster system of the CFD LAB at the University of Manitoba.

The far field acoustics generated by turbulent flow over rough surfaces has been experimentally investigated in an acoustically treated wall jet facility. The facility allows direct measurement of the far field sound from small patches of surface roughness, without contamination from edge or other aerodynamic noise sources. The facility is capable of generating turbulent boundary layer flows with momentum thickness Reynolds numbers between 450 and 1160. The variation of surface conditions tested cover the range from hydrodynamically smooth surfaces through most of the transitional range, with h+ variations from 3 to 85. Single microphone narrow band acoustic spectra, measured in the far field, show sound levels as much as 15 dB above the background from 0.186 m2 roughness patches. The measurements revealed the spectral shape and level variations with flow velocity, boundary layer thickness, and roughness size; providing the first data set large enough to assess the affects of many aerodynamic properties on the acoustic spectra. Increases in the size of grit type roughness produced significant increases in acoustic levels. Patches of hydrodynamically smooth roughness generated measurable acoustic levels, confirming that acoustic scattering is at least one of the physical mechanisms responsible for roughness noise. The shapes of the measured spectra show a strong dependence on the form of the surface roughness. The acoustic spectra generated by periodic two-dimensional surfaces have a much narrower louder peak than that generated by three-dimensional grit type roughness. Measurements also show the orientation of the two-dimensional surface significantly affects the acoustic levels and directivity. The variation of sound levels with flow velocity and roughness size suggests the acoustic field is significantly affected by changes in the near wall flow due to the presence of the roughness. Current models of noise generated by rough surfaces predict the general trends seen in measurements for flows over grit and two-dimensional roughness in the range of 20<h+<50. However, in cases with a low Reynolds number or large grit size, where the roughness is likely to significantly affect the hydrodynamic pressure field, the scattering models did not perform as well. / Ph. D.