Browsing by Author "Qasim, Ali Mohammed"
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Item Numerical predictions of fluid flow around a low rise building(Texas Tech University, 1995-08) Qasim, Ali MohammedAdvancement of Computational Fluid Dynamics (CFD)and computer modeling offers a whole new direction for understanding engineering problems. Research work in wind engineering has also been restructured to make use of this advancement. In contrast to aeronautical engineering, the CFD era started only recently in the wind engineering community. As a result, few practitioners have used CFD codes as their design tools. A number of turbulence models have been developed in the last two decades, ranging from the zero-equation mixing length model to the multi-equation turbulence models. Of these numerous models, the two-equation k -8 turbulence model has been widely used primarily due to its simplicity and realistic predictions. The standard k -8 turbulence model is known to successfully predict simple turbulent flows such as boundary layer flows and flows in plane ducts with no recirculation. Although, in the numerical solution of the governing flow equations, flow parameters such as mean velocity and mean pressure are readily available, the fluctuating pressures are rarely computed because of the fact that the finite difference equations solved for do not contain fluctuating values of these variable readily. In this research study, two methods are presented to compute the r.m.s. pressure coefficients after solving the flow equations.Item The product mix problem for manufacturing of silicon wafers by diffusion process(Texas Tech University, 1988-08) Qasim, Ali MohammedIn silicon wafer manufacturing there are several types of processes conducted in diffusion furnaces with different processing times. Each of these furnaces is dedicated for one type of process. The same type of process can be performed on any of the available furnaces dedicated for that particular process. These furnaces can be grouped in a single aisle or several aisles. The silicon wafers go through a series of controlled environment diffusion furnaces. These furnaces are rarely used to their capacity. A typical efficiency of these furnace tubes is somewhere between 28 to 35% [9]. This efficiency can be increased by assigning the proper number of wafers to these furnace tubes. The problem of finding the number of tubes required for each process to maximize the production is dealt with in this study.