| Summary: | 碩士 === 國立中興大學 === 機械工程學系 === 93 === In this study, the vorticity-stream function formulations are used to simulate the transient flow past a surface-mounted square cylinder and straight channel. A Dirichlet- type vorticity boundary condition based on the circulation and Stoke theorem is proposed at the solid surface. The no-slip condition at the solid surface is satisfied by producing vorticity near it. The PSOR iteration method is used to solve stream function equation;The transport and diffusion of vorticity in the flow field is simulated by solving the vorticity transport equation.
One of the main purpose in this study is to observe the dynamical process of the vorticity and stream function in the flow field. Four Reynolds numbers are used in the simulation ,which are 1,10,100 and 200 . The results show that the dimension of the separation region at the leftside of the square cylinder decreases with Reynolds number,but the dimension of the separation region at the rightside of the square cylinder increases with Reynolds number.
The slope of pressure coefficient vs x-distance is -0.2399 in the straight channel calculation for Reynolds number 100,that is very close to the theoretical value —0.24.
The pressure-drop difference between the surface-mounted square cylinder and straight channel at the 14 diameter length is -1.27 .
On the other hand ,the flow behavior in the entrance zone are re-examined.
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