三维空间中沙粒旋转对其跃移轨迹的影响  

Effect of Sand Particle Rotation on Saltating Trajectory in A Three-dimensional Space

作　　者：赵国丹[1] 张军杰[1] 亢力强[1] 邹学勇[1] 张春来[1] 程宏[1] 

机构地区：[1]北京师范大学地表过程与资源生态国家重点实验室/防沙治沙教育部工程研究中心,北京100875

出　　处：《中国沙漠》2016年第4期891-901,共11页Journal of Desert Research

基　　金：国家自然科学基金项目(41330746;41271020);国家"211工程"项目"高等学校仪器设备和优质资源共享系统"(cers-1-109)

摘　　要：风沙流中沙粒旋转通常具有明显的三维旋转特性。本文通过数值建模考察了三维空间中不同沙粒旋转状态所产生的Magnus力对其跃移运动轨迹特征的影响。在三维坐标系中,X、Y、Z轴分别表示水平、垂直和横向方向,气流沿X方向流动,沙粒起跳时位于XY平面内。结果表明,跃移沙粒仅绕Z轴旋转起跳时,初始起跳角速度的增大会导致在XY平面内的跃移高度和跃移距离减小而降落角增大,但Z方向没有运动发生。跃移沙粒仅绕X轴或Y轴旋转起跳时,绕X轴或Y轴的初始起跳角速度的变化对在XY平面内的跃移轨迹特征量没有显著影响,但沙粒偏离XY平面的偏离距离和偏离角的绝对值随起跳角速度绝对值的增加而增大。因此,沙粒起跳旋转状态对其跃移轨迹有重要的影响。Sand particle rotation in windblown sand movement usually has obvious three-dimensional rotation characteristics. In this paper, a numerical model is developed to study the effect of Magnus force on the sal- taring trajectory under different particle rotation conditions in three-dimensional space. In the three-dimen- sional coordinates, the X, Y and Z axes denote the horizontal, vertical and transverse directions, respec- tively. The air flow is along the X direction and the sand particle starts to eject in the XY plane. The re- sults show that when the particle ejects only with rotation around Z axis, with increase of ejected angular velocity, the saltation height and distance in XY plane decrease, the falling angle increases, but no motion occurs in Z direction. When the particle ejects only with rotation around X or Y axis, the ejected angular velocity has no obvious effect on the trajectory characteristics in XY plane, while the absolute values of de- viation distance and deviation angle increase with the absolute value of ejected angular velocity. Hence, the ejected rotation condition of sand particle has an important effect on its saltation trajectory.

关 键 词：三维空间 沙粒旋转 Magnus力 跃移轨迹 

分 类 号：X169[环境科学与工程—环境科学]