The impact of a vortex ring on a wall
The impact of a vortex ring on a wall
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DOI：
10.1017/s0022112087002027
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发表时间：
1987-08
影响因子：
3.7
通讯作者：
J. Walker;C. R. Smith;A. W. Cerra;T. Doligalski
中科院分区：
文献类型：
--
作者：
J. Walker;C. R. Smith;A. W. Cerra;T. Doligalski
对于不可压缩流体，研究了涡环在垂直于平面壁的轨道上靠近平面壁时的诱导流动。用水中的染料显示环内和平面附近的流动，实验观察了各种层流环环与近表面流动相互作用的详细特征。得到了环的运动轨迹以及壁面上发展的非定常边界层流动的数值解。实验和理论结果表明，边界层流动中形成了附壁二次环形式的非定常分离。随后发生了一个边界层爆炸性增长的时期，并以二次涡环从边界层喷出的形式发生了强烈的粘性-无粘性相互作用。然后，主环与副环相互作用，在某些情况下，观察到在壁面附近形成第三个三环。在较宽的雷诺数范围内对这一过程的细节进行了研究。结果清楚地显示了一个涡环如何通过与靠近壁面的粘性流动的非定常相互作用而产生另一个涡环。
The flow induced by a vortex ring approaching a plane wall on a trajectory normal to the wall is investigated for an incompressible fluid which is otherwise stagnant. The detailed characteristics of the interaction of the ring with the flow near the surface have been observed experimentally for a wide variety of laminar rings, using dye in water to visualize the flow in the ring as well as near the plane surface. Numerical solutions are obtained for the trajectory of the ring as well as for the unsteady boundary-layer flow that develops on the wall. The experimental and theoretical results show that an unsteady separation develops in the boundary-layer flow, in the form of a secondary ring attached to the wall. A period of explosive boundary-layer growth then ensues and a strong viscous-inviscid interaction occurs in the form of the ejection of the secondary vortex ring from the boundary layer. The primary ring then interacts with the secondary ring and in some cases was observed to induce the formation of a third, tertiary, ring near the wall. The details of this process are investigated over a wide Reynolds number range. The results clearly show how one vortex ring can produce another, through an unsteady interaction with a viscous flow near the wall.