Krause Egon
Aerodynamisches Institut, RWTH Aachen, Aachen, Germany.
Naturwissenschaften. 2003 Jan;90(1):4-26. doi: 10.1007/s00114-002-0386-z. Epub 2003 Jan 9.
Vortex motion plays a dominant role in many flow problems. This article aims at demonstrating some of the characteristic features of vortices with the aid of numerical solutions of the governing equations of fluid mechanics, the Navier-Stokes equations. Their discretized forms will first be reviewed briefly. Thereafter three problems of fluid flow involving vortex loops and filaments are discussed. In the first, the time-dependent motion and the mutual interaction of two colliding vortex rings are discussed, predicted in good agreement with experimental observations. The second example shows how vortex rings are generated, move, and interact with each other during the suction stroke in the cylinder of an automotive engine. The numerical results, validated with experimental data, suggest that vortex rings can be used to influence the spreading of the fuel droplets prior to ignition and reduce the fuel consumption. In the third example, it is shown that vortices can also occur in aerodynamic flows over delta wings at angle of attack as well as pipe flows: of particular interest for technical applications of these flows is the situation in which the vortex cores are destroyed, usually referred to as vortex breakdown or bursting. Although reliable breakdown criteria could not be established as yet, the numerical predictions obtained so far are found to agree well with the few experimental data available in the recent literature.
涡旋运动在许多流动问题中起着主导作用。本文旨在借助流体力学控制方程——纳维-斯托克斯方程的数值解来展示涡旋的一些特征。首先将简要回顾其离散形式。此后将讨论涉及涡旋环和涡旋丝的三个流体流动问题。在第一个问题中，讨论了两个相互碰撞的涡旋环的时间相关运动及其相互作用，预测结果与实验观测结果吻合良好。第二个例子展示了在汽车发动机气缸的吸气冲程中涡旋环是如何产生、移动并相互作用的。经实验数据验证的数值结果表明，涡旋环可用于在点火前影响燃油液滴的扩散并降低燃油消耗。在第三个例子中，表明在有攻角的三角翼上的空气动力学流动以及管道流动中也会出现涡旋：这些流动的技术应用特别感兴趣的是涡旋核心被破坏的情况，通常称为涡旋破裂或爆发。尽管尚未建立可靠的破裂准则，但到目前为止获得的数值预测结果与近期文献中为数不多的实验数据吻合良好。
