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變動時間步長在加速數值模擬紊流流場收斂之研究
Thesis

變動時間步長在加速數值模擬紊流流場收斂之研究

蔡文彬
Masters, National Tsing Hua University
1999

Abstract

Varying Time StepsizeConvergence AccelerationTurbulent Flow Computation 變動時間步長加速收斂紊流計算
In this study, numerical computations by simple SIMPLE (LBL), PISO (LBL+PISO), pre-conditioned Bi-CGSTAB on SIMPLE, and pre-conditioned Bi-CGSTAB on PISO are computed for some problems to demonstrate the effectiveness of the algorithm pre-conditioned Bi-CGSTAB on SIMPLE. This method is also applied to evaluate the heat transfer and fluid flow behavior in a rectangular channel with streamwise-periodic ribs mounted on one of the principal wall. The numerical results show that all the models tested can predict the flowfield reasonable well, and the inclusion of Yap term in the equation (or equation) can further improve the prediction of heat transfer coefficient in these models, model and model. Furthermore, a design of varying step size concept both in time span and spatial coordinate systems to achieve fast convergence is also demonstrated. The determination of the step size based on the concept of minimization of residuals by the Bi-CGSTAB algorithm is proposed. The numerical results show that the time stepsize adjustment based on the Bi-CGSTAB method improves the convergence rate for turbulent computations using advanced turbulence models in low-Reynolds number forms, and the degree of improvement increases with the degree of complexity of the turbulence models.

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