Azimuthal instability of a vortex ring computed by a vortex sheet panel method
Azimuthal instability of a vortex ring computed by a vortex sheet panel method
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DOI：
10.1088/0169-5983/41/5/051405
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发表时间：
2008-11
影响因子：
1.5
通讯作者：
H. Feng;Leon Kaganovskiy;R. Krasny
中科院分区：
文献类型：
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作者：
H. Feng;Leon Kaganovskiy;R. Krasny
提出了三维流动中涡片运动的拉格朗日面板法。薄片由一组具有树形结构的四边形面板表示。面板有进行循环的主动颗粒和用于自适应细化的被动颗粒。对Biot-Savart核进行正则化，并用树码计算速度。应用该方法从扰动圆盘涡片的初始条件出发，计算了涡环的方位不稳定性。通过跟踪板材表面上的材料线来阐明芯动力学的细节。结果显示了以下一系列事件：薄片螺旋卷起成环，环轴波浪形变形，涡旋核在每个波长上的第一次坍缩，涡旋核与第一次坍缩相异的第二次坍缩，环绕在核心周围的环的形成和小环的径向喷射。涡旋核的崩塌与轴向流的辐合有关。
A Lagrangian panel method is presented for vortex sheet motion in three-dimensional (3D) flow. The sheet is represented by a set of quadrilateral panels having a tree structure. The panels have active particles that carry circulation and passive particles used for adaptive refinement. The Biot–Savart kernel is regularized and the velocity is evaluated by a treecode. The method is applied to compute the azimuthal instability of a vortex ring, starting from a perturbed circular disc vortex sheet initial condition. Details of the core dynamics are clarified by tracking material lines on the sheet surface. Results are presented showing the following sequence of events: spiral roll-up of the sheet into a ring, wavy deformation of the ring axis, first collapse of the vortex core in each wavelength, second collapse of the vortex core out of phase with the first collapse, formation of loops wrapped around the core and radial ejection of ringlets. The collapse of the vortex core is correlated with converging axial flow.