溶解椭圆颗粒沉降的介观尺度数值模拟  

Mesoscale simulation of the sedimentation of melting elliptical particle

作　　者：刘汉涛[1] 江山[2] 王艳华[1] 王婵娟[1] 李海桥[1] 

机构地区：[1]中北大学能源环境工程与计算流体力学实验室,太原030051 [2]密苏里大学土木与环境工程系

出　　处：《物理学报》2015年第11期256-263,共8页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:51476150);山西省国际科技合作项目(批准号:2014081028);山西省高等学校科技创新项目资助的课题~~

摘　　要：在任意拉格朗日欧拉(ALE)算法模拟有热对流影响的颗粒两相流动的直接数值模拟基础上,通过建立颗粒溶解速度和颗粒表面热流密度的关系,对溶解的椭圆颗粒在垂直管道内牛顿流体中的沉降进行了直接数值模拟.计算结果表明:与等温惰性椭圆颗粒沉降相比,流体的对流运动、颗粒质量以及形状的变化等因素使溶解的椭圆颗粒在不同初始角度沉降时,颗粒沉降动态尾迹、颗粒受力、颗粒沉降速度等都发了较大变化.In this paper, a mathematical relationship between particle melting rate and its surface heat flux is established to solve the problem of melting of elliptical particle sedimentation based on the direct numerical simulations of particle sedimentation when taking account of thermal convection within the framework of the arbitrary Lagrangian-Eulerian technique. The elliptical particle with different initial angles is released in a mesoscale channel under gravity. Compared with the isothermal elliptical particle sedimentation, the melting elliptical particle shows large differences in moving trajectories, the forces exerting on the particle and velocities, which come from the consideration of fluid convection, mass loss, and shape change. More specifically, 1） in the case of isothermal elliptical particle sedimentation, the velocity, the horizontal trajectory, and the force vary periodically. However, the amplitude recedes gradually, and finally becomes zero in the case of the melting elliptical particle, which is caused by the mass lost and shape change. 2） The equilibrium position of the major axis will finally be perpendicular to the direction of sedimentation. So, the initial angle of slope （θ） usually affects the sedimentation in the beginning, and vanishes after a period of time. 3） The downward convection induced by the cold fluid accelerates the velocity of the melting particle. The angular velocity, force and horizontal amplitude of the melting particle become smaller than those of the isothermal particle, and finally recedes to zero. In our study, the investigation of coupled heat transfer, fluid-solid system and shape change is carried out, and some new features are found out.

关 键 词：介观尺度 溶解 椭圆颗粒 直接数值模拟 

分 类 号：O359[理学—流体力学]