欧拉对称量预测波动Taylor涡流的紊态弥散

Chaotic Dispersion Prediction of Wavy Taylor-vortex Flow with Eulerian Symmetry Measures

在完成数值计算的波动Taylor涡流中研究粒子传递时 ,可采用一个有效轴扩散系数去预测由紊态平流所产生的混合 ,而Dz 与两个对称偏差的积成正比 .一个是来自旋转对称的平均偏差 ,另一个是来自自由弯曲的平均偏差 .因为这些量直接由流场得到 ,称为欧拉对称量 .这样就得出 :在流动中的宏观传递性质可直接以流场和梯度来量化 。

In a recent investigation of particle transport in numerically computed wavy Taylor vortex flow. Rudman estimated an effective axial diffusion coefficient D z to characterize the enhanced mixing due to chaotic advection. It is found that D z is proportional to the product of two measures of symmetry deviation. The first is a measure of the average deviation of the flow from rotatonal symmetry and the second is a measure of the average deviation from flexion free flow (a flow where the curl of the vorticity is zero). Because these quantities are obtained directly from the velocity field, which are called Eulerian symmetry measures. The macroscopic transport behavior is shown in a flow and can be quantified directly in terms of the velocity field and its gradients, and the connection between Eulerian and Lagrangian pictures of transport is provided, a problem of fundamental and widespread interest.