论文标题
流体惯性扭矩是一种有效的旋转机制，用于沉降细长的微晶状体
Fluid inertial torque is an effective gyrotactic mechanism for settling elongated micro-swimmers
论文作者
论文摘要
海洋浮游生物通常被建模为延伸的细长微型释放器。我们第一次考虑了这样的游泳者对流体惯性引起的扭矩，我们发现它们自发地朝着重力相反的方向游泳。我们使用直接数值模拟分析了静态流体中游泳者的平衡方向和湍流中的平均方向。与众所周知的陀螺机制相似，可以通过有效的重新定向时间尺度来量化流体惯性扭矩的影响。我们表明，游泳者的方向在很大程度上取决于重新定位时间尺度，而游泳者在时间尺度的Kolmogorov时间尺度相同时表现出强烈的优先对齐。我们的发现表明，流体惯性扭矩是陀螺仪的新机制，可稳定微晶状体（如浮游生物）的向上定向。
Marine plankton are usually modeled as settling elongated micro-swimmers. For the first time, we consider the torque induced by fluid inertia on such swimmers, and we discover that they spontaneously swim in the direction opposite to gravity. We analyze the equilibrium orientation of swimmers in quiescent fluid and the mean orientation in turbulent flows using direct numerical simulations. Similar to well-known gyrotaxis mechanisms, the effect of fluid inertial torque can be quantified by an effective reorientation time scale. We show that the orientation of swimmers strongly depends on the reorientation time scale, and swimmers exhibit strong preferential alignment in upward direction when the time scale is of the same order of Kolmogorov time scale. Our findings suggest that the fluid inertial torque is a new mechanism of gyrotaxis that stabilizes the upward orientation of micro-swimmers such as plankton.
