Analysis of Three-Dimensional Viscous Internal Flows.

Abstract

Abstract : In the first research category, two different areas were studied: Analysis of laminar duct flows, and study of laminar and turbulent separated flows. These studies were aimed at acquiring a better understanding of isolated physical phenomena significant to turbomachinery applications via the use of appropriate model problems. The second research category is aimed at obtaining flow-dependent computational grids efficiently so that critical regions can be accurately modeled. The final research category includes the analysis of numerical methods, with the goal of improving the efficiency and accuracy of the various methods developed and implemented. Preliminary fine-grid marching solutions were obtained in the entrance region of the duct for eight different duct configurations. Streamwise separation was examined, using the model problem of laminar flow through a constricted asymmetric channel. True transient results were obtained for several flow configurations with extremely fine grids, so as to provide benchmark solutions which can permit assessment of other solutions obtained using approximate methods. Turbulence modeling was pursued, with the wall region being described by low-remodeling. Although the wall region can be modeled more accurately by this method, the fine grids required retard the convergence rate of the approximate factorization method used. Flow-dependent grids were generated for a 1-D nonlinear viscous Burgers' equation. For the first time, accurate results were computed using totally central-difference schemes for Re up to 10,000. Finally, in the last category, in the area of semi-implicit methods, a multi-grid method was developed to provide fine-grid solutions for the Neumann problem.