| Summary: | 碩士 === 國立臺灣大學 === 機械工程學研究所 === 87 === The main purpose of this study is to simulate numerically the two-dimensional, inviscid, transient cross-flow around a projectile during the unfolding process of the wrap-around fins. Euler equations are to be analyzed. The numerical technique employed is the TVD （Total Variation Diminishing）method accompanied with the Chimera scheme and collar grids.
The collar grids are used to resolve the deficiency of Chimera scheme in data transfer when the fins and projectile are very close to each other. The validity of the numerical scheme proposed by the present study in simulating such a unsteady flow problem is then justified .
The numerical results indicate that circulatory flows appear first in the second and third quadrant of the flow field between fins during the unfolding process. At the moment when the fins are completely unfolded, the pressure distribution along the surface of projectile and fins varies drastically, resulting a net rolling moment on the projectile. In the mean time, a new circulatory flow starts to grow in the first quadrant of the flow field between fins, while the one in the third quadrant decays. When the flow field approaches the steady state, only the circulatory flows with comparable strength in the first and second quadrants remain. The variation of pressure distribution along the projectile and fin surfaces at the steady state become much milder than that at the transient state.
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