方管中中性回转扁球颗粒纵横比对平衡位置的影响  

Effect of neutrally buoyant oblate spheroid’s aspect ratio on its equilibrium position in a square duct

作　　者：李洋 梁宏[2] 夏振华 LI Yang;LIANG Hong;XIA ZhenHua(Institute of Fluid Engineering,School of Aeronautics and Astronautics,Zhejiang University,Hangzhou 310027,China;Department of Physics,Hangzhou Dianzi University,Hangzhou 310018,China)

机构地区：[1]浙江大学航空航天学院流体工程研究所,杭州310027 [2]杭州电子科技大学物理系,杭州310018

出　　处：《中国科学：物理学、力学、天文学》2022年第10期87-99,共13页Scientia Sinica Physica,Mechanica & Astronomica

基　　金：国家自然科学基金(编号:91852205)资助项目。

摘　　要：本文使用多松弛格子Boltzmann方法对方管中中性回转扁球颗粒的惯性迁移进行了数值模拟.研究了不同初始位置、初始朝向和雷诺数Re下,扁球颗粒的纵横比AR对平衡位置的影响.这里考虑了AR=0.5,0.75,1等三种不同的纵横比.与之前研究不同的是,这里调节AR时仅改变回转扁球颗粒的半短轴长度(极轴半径),而半长轴长度(赤道半径)保持不变,因此颗粒的体积和质量会随着AR的增加而增加.在低雷诺数(Re=80)下,受初始位置和初始朝向影响,颗粒存在翻转模态、滚动模态和倾斜滚动等三种运动模态.虽然运动模态不一样,但是不同AR的颗粒在达到稳态后都具有相同的旋转直径.在翻转模态下,AR会影响扁球颗粒的平衡位置,随着AR的增大,颗粒的平衡位置会逐渐靠近管道中心.在倾斜滚动模态下,AR会部分影响颗粒的平衡位置,当AR从0.5变化到0.75,颗粒相应的平衡位置几乎保持不变,而球形颗粒(AR=1)的平衡位置则更靠近管道中心.而在滚动模态下,AR几乎不影响颗粒的平衡位置.此外,我们还发现相同模态下,颗粒的平衡位置在40≤Re≤160范围内会随着Re的增加而向壁面靠近.The inertial migration of a neutrally buoyant oblate spheroid in a square duct is numerically simulated via the multiplerelaxation-time lattice Boltzmann method.This study aims to investigate the effect of a particle’s aspect ratio(AR)on its equilibrium position at different initial positions,orientations,and Reynolds numbers(Re).The spheroid’s equatorial radius remains unchanged here,and its AR is adjusted by changing its polar radius,which is distinct from previous studies.Therefore,the particle’s volume and mass increase with the AR.At a low Re(Re=80),the particle’s initial position and orientation affect its final motion.There are three possible motion modes,tumbling,log-rolling and inclined log-rolling.Although the oblate spheroids with different ARs may experience different motion modes at their final equilibrium states,their rotational diameters are constant.For the tumbling mode,the AR affects the equilibrium position,and the particle gradually approaches the duct center as the AR increases.For the inclined log-rolling mode,the AR partially affects the equilibrium position,where the corresponding equilibrium positions remain unchanged for the spheroids with AR=0.5 and 0.75,approaching closer to the duct center for the spherical particle with AR=1.Finally,for the log-rolling mode,AR has a negligible effect on the equilibrium positions.Furthermore,in the same motion mode,the particle’s equilibrium position approaches the wall as the Re increases from 40 to 160.

关 键 词：格子BOLTZMANN方法 纵横比 旋转直径 惯性迁移 回转扁球颗粒 方管 

分 类 号：O35[理学—流体力学]