Abstract: Direct numerical simulations were conducted to investigate the behavior of heavy particles in homogeneous isotropic turbulence. The present study focused on the effect of particle inertia on the autocorrelations of the particle velocity and the fluid velocity seen by particles and the dispersion characteristics of particles. The Lagrangian integral time scale of particles monotonically increased as the magnitude of the particle response time increased, while that of the fluid seen by particles remained relatively constant.It reached maximum when the particle response time was close to the Kolmogorov time scale of the flow. Particle dispersion increased as the particle inertia increased for small particles;while for larger particles, it decreased as particle inertia increased.Particle eddy diffusion coefficient was maximal and greater than that of the fluid by about 30% when the preferential concentration was most obvious. The concentration field of the particles with τ_p/τ_k≈1.0 showed that particles tended to be collected in regions of low vorticity (high strain) due to preferential concentration.

摘要： 对三维气粒两相各向同性湍流进行了直接数值模拟以研究悬浮在其中的颗粒的运动.重点考察了颗粒惯性对颗粒和颗粒所见流体速度的自相关以及颗粒弥散特性等的影响.颗粒的Lagrangian积分时间尺度随颗粒惯性单调增加，颗粒所见流体速度的Lagrangian积分时间尺度保持相对稳定;当颗粒的弛豫时间尺度与流体的Kolmogorov时间尺度相当时，流体Lagrangian积分时间尺度有较大偏离.当颗粒的惯性很小时，颗粒扩散随惯性增大而增强，但当颗粒的惯性大于一定值时，颗粒的扩散性反而减弱，局部富集明显时颗粒扩散系数最大，此时颗粒的涡扩散系数可比流体的高约30%.τ_p/τ_k≈1.0的颗粒的浓度场显示，由于局部富集效应颗粒倾向于集中在低涡度高剪切的区域.