均匀各向同性湍流中颗粒所见被动标量的数值研究

Numerical Investigation of Passive Scalar Seen by Inertial Particle in Homogeneous Isotropic Turbulence

对均匀各向同性湍流中惯性颗粒所见被动标量的统计特性进行了数值模拟研究,探讨了颗粒惯性的差异对统计结果的影响.结果表明,颗粒所见流体标量的自相关特性随颗粒惯性的增加而单调减少;颗粒所见流体标量脉动和耗散率随颗粒惯性的变化呈现出复杂的变化行为,在St=1.0附近分别达到最小和最大值,其原因是St=1.0的临界颗粒聚集于低涡量、高应变区域和标量场在高应变区域形成强耗散的片状结构所致.

The statistical properties of passive scalar in homogeneous isotropic turbulence seen by inertial particle were studied by direct numerical simulation. The influence of particle inertia on statistical results was discussed. The results show that the self-correlation of scalar seen by particle decreases monotonously with the increase of particle inertia; that the variance and dissipation rate of scalar seen by particle display complicated behavior with the change of St number of particle and reach the minimal and maximal values at the vicinity of St = 1.0, respectively. The reasons are that critical particles with St = 1.0 aggregate in high strain and low vorticity regions and that sheet structures with strong scalar dissipation form in those regions.