圆柱周围湍流和含沙多相流的SPH数值模拟

SPH numerical simulation of turbulent and sandy multiphase flow around a cylinder

湍流和多相流是流体力学中最具挑战性的两个主题,湍流多相流的实验和数值模拟更是一项艰巨的挑战.此外,对颗粒干沉积方面的多相流、多尺度、多物理耦合特征的风沙流的综合实地观测仍然很少.因此,本文综合考虑湍流、多相流与多物理耦合等方面,采用以圆柱为干扰物产生对流涡流的强制干扰技术,以塔克拉玛干沙漠地带中和田至若羌铁路的过沙桥桥墩为研究背景.为摆脱有限元软件中由网格大变形或失真引起的各种问题,采用SPH方法的宏观界面追踪和微观单点追踪相结合的方式,初步揭示了以单相对流涡流为风场背景的含沙多相流环境下的圆柱周围复杂的流场变化以及对颗粒干沉积运动的影响.采用数值模拟与现场实验相结合的方式,着重对计算域边界壁面和圆柱壁面对空气单相流中对流涡流的成形运动及其特征分析、两相流中对流涡流在圆柱周围的夹沙运动模拟及其特性分析、两相流中对流涡流的夹沙率以及边界壁湍流对沙粒干沉积效率展开分析研究.

Turbulence and multiphase flow are two of the most challenging topics in fluid mechanics,and the experimental and numerical simulation of turbulent multiphase flow is a formidable challenge.Furthermore,comprehensive in-situ observations of wind-sand flows characterized by multiphase flow,multiscale,and multi-physics coupling in grain dry deposition are still rare.Therefore,this study comprehensively considers turbulence,multiphase flow and multi-physics coupling,and adopts the forced interference technique of generating convective eddy currents with cylinders as interferences.In order to get rid of various problems caused by large deformation or distortion of the mesh in the finite element software,the combination of macro-interface tracking and micro-single-point tracking of the SPH method is used to preliminarily reveal the complex flow field around the cylinder in the sand-containing multiphase flow environment with single-phase convective eddy current as the wind field background.The combination of numerical simulation and field experiment is used to analyze the forming motion and characteristics of the convective vortex in the air single-phase flow on the boundary wall and the cylindrical wall of the computational domain,the simulation and characteristic analysis of the sand movement of the convective vortex around the cylinder in the two-phase flow,the sand rate of the convective vortex in the two-phase flow and the dry deposition efficiency of the boundary wall turbulence.