The Transient Mixed Convection of Viscoelastic Fluid Flows Past a Backward Facing Step with High Richardson Number

• Main Authors: Jun-Jia Huang, 黃俊嘉
• Other Authors: Cheng-Hsing Hsu
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/28378125195498982937

碩士 === 中原大學 === 機械工程研究所 === 95 === The transient mixed convection of viscoelastic fluid flows with high Richardson number past a backward facing step was studied. By varying the Reynolds number and the elastic coefficient, the study explores the flow pattern of the viscoelastic fluid with high Richardson number past a backward facing step. The flow fields are numerically studied. The finite difference method is applied to the vorticity, stream and energy equations. The Gauss-Seidel method with successive over-relaxation is implemented to obtain solutions. When the Richardson number is 12, the Reynolds number is 50 and the elastic coefficient is 0.001, the results indicate that a secondary recirculation is formed in the primary flow at the downstream of the step. In addition, the secondary recirculation is dissipated when the steady state of the flow field is approached. Thereafter, a transient coexistent multiple-recirculation phenomenon exhibits at the downstream of the primary recirculation when the Richardson number is 16, the Reynolds number is 50 and the elastic coefficient is 0.001. Finally, it is also dissipated when the steady state of the flow field is reached. With fixed Richardson number and the elastic coefficient, increasing the Reynolds number up to 75, the primary recirculation is developed and produces four secondary recirculations. This situation is similar to the flow pattern of the Karman vortex street.