三维混合层中湍流拟序结构对颗粒扩散的影响

对时间发展模式的三维气固两相混合层湍流拟序结构及其对不同尺寸颗粒扩散的影响进行直接数值模拟，对于气相场，应用拟谱方法（Pseudospectral method）直接求解Navier-Stokes方程组；对于颗粒场，对于Lagrangian方法跟踪半场颗粒，针对不同Stokes数的颗粒，分别模拟颗粒场在展向和流向的分布变化，进而分析流场三维大涡结构对不同颗粒扩散的影响，并引入一系列参数，着重定量描述流场展向大涡结构和流向大涡结构对不同尺寸颗粒分布的不同影响。

Particle Dispersion Affected by Turbulent Coherent Structures in a Three-Dimensional Mixing Layer

Direct numerical simulation is employed to investigate the particle dispersion affected by the coherent structures in a three-dimensional temporal mixing layer. Pseudospectral method is used to solve the Navier-Stokes equations directly. Lagrangian approach is employed to trace the particles with different Stokes number distributed uniformity initially in the upper region of the mixing layer. The simulating results show that the particle dispersion patterns are still strongly dependent on the large-scale vortex structures and the three-dimensionality. Particles with Stokes number of the order of unity were found to have the largest concentration on the outer edges of the spanwise large-scale vortex structures,and the variation of particle concentration along the spanwise direction increased with the development of the three-dimensionality. Furthermore,it is found that the particle dispersion is influenced more by the spanwise vortex structures than by the streamwise vortex structures.