الفهرس 
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Abstract
A numerical study of two- and three- dimensional turbulent obstacle flows : The thesis presents numerical computations of two- and three-dimensional incompressible turbulent flows around prismatic obstacles. Thes flows are not only relevant to engineering applications related to wind engineering and cooling of electronic components, but also exhibit most of the complex and challenging features associated with multiple flow separation and reattachment. The thesis addresses the two central issues in the computational modeling of such flows: numerical accuracy and turbulence modeling. The computational method is based on a finite-vogume solution of the time-averaged Navier-Stokes equations. In order to assure numerical stability without introducing unacceptable level of numerical diffusion, a QUICK-type higher-order upwind biased differencing scheme was formulated and implemented. The scheme is bounded, stable, and retains transvers curvature (TC) correction terms for both cross-stream directions. To achieve an improved representation of turbulent transport processes and the eddy viscosity, a multipe-time-scal (MS) model which is based on a variable partitioning method of the turbulent energy spectrum is implemented in the computer code. Two- and Three-dimensional laminar obstacle flows are used to validate the computer code and the different elements of the numerical method. The numerical predictions using the QUICK-TC scheme are found to be in excellent agreement with available experimental data and show that : i- Three-dimensional effects can be important in the recirculation regions, and ii- The use of higher-order differencing is essential for such flows.