充分发展尾流中粒子运动机制的研究

运用直接数值模拟方法(谱元)对圆柱尾流(Re￡175)进行计算，计算结果与实验结果吻合良好。在获得精确流场基础上，运用拉哥朗日法对充分发展尾流中的粒子(St=4)运动进行研究，同时考虑粒子之间的相互作用。研究发现，粒子在充分发展尾流中集聚于相邻涡团之间区域，该现象很大程度上决定于流场的横向速度分布。此外，粒子扩散分布清晰显示涡团轮廓。从粒子与当地流场相对速度的分布分析中可以得到粒子在尾流中的运动规律：在相邻涡团反向旋转作用下粒子围绕涡团做往复运动。因此粒子在充分发展尾流中的运动可以描述为：一边绕涡团运动，一边随涡团向尾部运动。

Investigation of the Mechanism of Particle Transfer in a Fully Developed Wake Flow

Spectral-element direct numerical simulation was conducted for the wake flow with Re below 175 and the result agreed well with experimental data. Based on the accurate gas-flow field obtained, Lagrangian tracking was used to study the dynamics of particles(St=4) and particle-particle interaction was considered. As a result, particles were found to preferentially concentrate at the thin region between adjacent vortex structures(TRAVS) and it was found to be determined by the reverse velocity of TRAVS. In addition, particle dispersion made out the outline of vortex and the particle-fluid relative velocity indicated the particle transfer in the fully developed wake: particles move around the vortex in an ellipse path under the stretch effect between counter-rolling adjacent vortexes. As such the mechanism of particle transfer in a fully developed wake can be explained as: move around vortexes and forward with wake flow.