| Summary: | 碩士 === 國立雲林科技大學 === 機械工程系碩士班 === 97 === Numerical simulation of flow past a two-dimensional flat plate in various angle of attack by spectral element method. In this study, particularly, we use a very thin flat plate with thickness t/c=1×10-5, to let it be similar to a straight line model and to reduce the effect of leading edge. The angle of attack of flat plate are simulated with α = 20 °, 30 °, 40 °, 50 °, in two inlet flow condition, Re=140, 200, respectively. The purpose of this research is using the spectral element method to obtain the flow field detail of the process of vortex formation, breakdown and also the vortex shedding phenomena in downstream. The vortex shedding frequency, Strouhal number, lift coefficient and drag coefficient are calculated as time goes on.
In the flow field, Re = 140, α = 20 °, of the flat plate, there was no occurrence of vortex shedding. The calculated Strouhal number declined as the degree of angle of attack increased. The drag coefficient would increase as the angle of attack increase. The lift coefficient would increase as the angle of attack increase in the range of α = 20 ° ~ 40 ° ,but drop suddenly in α = 50 °.
Global error in the relations with the adaptive mesh can be found. Although the global error are upward in the first three cycle. However, with the increase in the number of cycle error also decreased, until after 72 of cycle the error was convergence, the .006 of percent global error rate dropped to below 0.002%. Comparison of different adaptive mesh Results of U velocity, V velocity, vorticity contour.
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