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本文通过对非定常轴对称流动的完全的N-S方程组的数值积分考察了浸没在均匀流中的孤立的轴对称涡旋的破裂。结果表明:当旋涡强度较弱时,旋涡是稳定的,解将渐近一定常流动,准圆柱形近似是对这种流动的极好的近似;当旋涡强度足够大时,解将是非定常的,存轴线附近将形成一个回流区,其形状和内部结构与Faler andLeibovich(1978)所观测到的内部为多包结构的破裂包十分相像。在适当的流动参数的组合下,流动将在若干时间以后呈现准周期性。用准圆柱形近似所作的平行的计算表明:就预测旋涡的破裂而言,两种方法的结果相当吻合。它们一致表明:至少在本计算所及的较低的雷诺数范围内,涡旋的破裂与雷诺数关系不大,且与上游流动的临界分类无关。
In this paper, the rupture of an isolated axisymmetric vortex immersed in a uniform flow is investigated by numerical integration of a complete N-S system of unsteady axisymmetric flows. The results show that the vortex is stable when the vortex intensity is weak and the solution will be asymptotically constant. The quasi-cylindrical approximation is an excellent approximation to this flow. When the vortex intensity is large enough, the solution will be unsteady , A recirculation zone will be formed near the storage axis. Its shape and internal structure are similar to the ruptured package with multi-pack structure observed by Faler and Leibovich (1978). With the appropriate combination of flow parameters, the flow will appear quasi-periodic after some time. The parallel calculations using the quasi-cylindrical approximation show that the results of the two methods are quite consistent in terms of predicting the vortex rupture. They consistently show that the vortex rupture has little to do with the Reynolds number, at least for the lower Reynolds numbers calculated in this calculation, and is not related to the critical classification of upstream flows.