关键词: Magnus效应, 流动结构, 非对称升力, 公式修正, 速度梯度

Abstract: In the course of wind-blown sand movement, sand particles usually leap with high-speed rotation, which generates lift force called Magnus effect. The Magnus force upon a single rotating sphere was investigated by means of numerical simulation for Re (Reynolds number) from 0.1 to 400 and rotational speeds from 100 to 1 000 rev·s-1. Results were compared with Magnus Force Formula deduced by Rubinow & Keller. For Re between 0.1 and 200, lift was in proportion with rotating speed, and it declined with the increase of Re. Meanwhile, Magnus effect has relation with the flow field patterns of a fixed sphere in a uniform flow: for attached flows, the lift coefficient ratio K by numerical simulation result and the Magnus Force Formula result declined with the increase of Re, and it reached a minimum value at Re=20~30; for symmetrically separated flows, however, K ascended with the increase of Re. At a higher Re of over 200, lift force caused by asymmetrical flow becomes greater than the Magnus force, but the Magnus effect can not be neglected. According to the numerical simulation results, an amending to the Magnus Force Formula was obtained. Since velocity gradient and Magnus force have no coupling effect, the impact of Magnus effect and velocity gradient on lift force can be linear superposed.

Key words: Magnus effect, flow patterns, asymmetric lift force, formula revision, velocity gradient