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The study applies in vivo technique for profiling hemodynamics and wall shear stress (WSS) distribution in human coronary arteries. The methodology involves fusion of 2D Intra Vascular Ultra Sound and Bi-plane angiograms to reproduce the 3D arterial geometry. This geometry is then used in a Computational Fluid Dynamics (CFD) module for flow modeling. The Walburn and Schneck constitutive relation was used to represent the non-Newtonian blood rheology. The methodology is applied to study the relationship between WSS and Neointimal Hyperplasia (NIH) in two groups of diabetic patients after being treated separately with bare metal stents (BMS) and Sirolimus Eluting Stents (SES). The stent assignments were blinded until the end of the study. The study was repeated for the patients after 9 months. The predicted WSS ranged from (0.1- 8 N/m2) and was categorized into five classes: low ( < 1 N/m2); low-normal (1-2 N/m2); normal (2-3 N/m2); high-normal (3-4 N/m2); high ( > 4 N/m2). The results indicate NIH in 5 of the patients treated with BMS and none in SES cases. These results correlate with our predicted WSS distribution.

High-Frame-Rate Oil Film Interferometry Jonathan Charles White This thesis presents the design and implementation of a high-frame-rate oil film interferometry technique (HOFI) used to directly measure skin friction in time dependent flows. Experiments were performed to determine the ability of a high-speed camera to capture oil film interferometry images. HOFI was found to be able to capture these interferometry images at frequencies up to 105 Hz. Steady laminar and turbulent flows were tested. Transient flows tested consisted of a wind tunnel ramping up in velocity and a laminar boundary layer which was intermittently tripped to turbulence by puffing air out of a pressure tap. Flow speeds ranged from 0 to 108 ft/sec and 10 and 50 cSt Dow Corning 200 dimethylpolysiloxane silicone oil was used. The skin friction was determined from the rate of change of the height of the oil film using lubrication theory. The height of the oil film was determined from the high speed camera interferogram images using a MATLAB script which determined fringe spacing by fitting a four-parameter sine wave to the intensity levels in each image. The MATLAB script was able to determine the height of the oil film for thousands of interferogram images in only a few minutes with sub-pixel error in fringe spacing. The skin friction was calculated using the oil film height history allowing for the direct measurement of skin friction in time dependent flows.

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This thesis reports on investigations carried out to study of the effect of horizontal wall jets on rough, fixed and mobile beds in open channel flow. Experimental tests were carried out, using fixed and mobile sediment beds. Computer simulation models for the flow within the jet and resulting sediment transport were developed and their results analysed in this study. In the experimental phase, tests were carried out with both fixed and mobile sediment beds. The shape of the water surface, numerous point velocity measurements and measurements of the evolving scour hole shape were made. Detailed descriptions of the turbulent flow field over a fixed rough bed and for scour holes at equilibrium were obtained for a range of initial jet conditions. Fully turbulent, multiphase flow was modelled using the Fluent Computational Fluid Dynamics software. This was used to analyze the flow caused by a jet in a rectangle open-channel with a rough bed, and also the flow pattern in a channel with a local scour hole. The volume of fluid (VOF) multiphase method and K- model was used to model the fluid flow in both cases. The model predictions of velocity and shear stress were compared against experimental observations. The experimental data was used to develop new empirical relationships to describe the pattern of boundary shear stress caused by a wall jet over fixed beds and in equilibrium scour holes. These relationships were linked with existing bed-load transport rate models in order to predict the temporal evolution of scour holes. An analytical model describing the relationship between the wall jet flow and the development of a local scour hole shape was reported and its predictions compared with experimental data.

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<p>High speed flows in engineering applications are often characterized by shock-wave/boundary layer interactions (SWBLI) and three-dimensional flows. This thesis aims to study commonly employed turbulence models in the context of configurations featuring SWBLI and 3D flows. Computational Fluid Dynamics (CFD) simulations of flow over a 20 degree isentropic compression curved fin were performed, and the results were compared with published experimental data. Two variations of the Spalart-Allmaras (SA) turbulence model, and two variations of the Menter Shear Stress Transport (SST) turbulence model were tested, and their ability to predict mean flow data was compared. All four models predict the correct flow structure, but the SA models display higher error in predicting Pitot pressure in the curved fin 3D boundary layer. CFD simulations of flow over a sharp fin were performed using the same four turbulence models, and mean flow data were compared to published experimental and computational data. Simulated flow profiles showed good accuracy in the regions away from the shock structure, but did not accurately predict flow in the supersonic regions in the vicinity of the shock wave. Time-accurate IDDES simulations of both configurations were performed, and neither configuration showed any deviation from the steady state solution.</p>