Transport of spherical gyrotactic organisms in general three-dimensional flow fields
Transport of spherical gyrotactic organisms in general three-dimensional flow fields
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DOI：
10.1063/1.3381168
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发表时间：
2010-04
影响因子：
4.6
通讯作者：
G. J. Thorn;R. Bearon
中科院分区：
文献类型：
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作者：
G. J. Thorn;R. Bearon
在本文中，我们认为球形生物体的方向是由粘性扭矩与自扶正扭矩（无论是由于底部沉重，形状，或通过优先游泳由于主动传感）的组合：一种现象称为回转。我们重申的稳定平衡取向，这样一个有机体在一个均匀的剪切流，它存在于所有的剪切值，如果两个扭矩是不平行的，只有当无量纲剪切是低于临界值，如果扭矩是平行的。我们计算长期的轨迹，这样的一个有机体的流动，其中包括线性运动的方向上的涡度和一个圆锥截面的剪切平面，例如，螺旋运动的情况下，纯旋转。我们计算的取向概率密度函数时，再取向与旋转扩散和显示，包括旋转扩散降低了平均游泳速度和旋转的平均平衡取向…
In this paper we consider spherical organisms whose orientations are determined by the combination of viscous torque with a self-righting torque (either due to bottom-heaviness, shape, or through preferential swimming due to active sensing): a phenomenon known as gyrotaxis. We restate the stable equilibrium orientation of such an organism in a homogeneous shear flow, which exists for all shear values if the two torques are not parallel, and only when the nondimensional shear is below a critical value if the torques are parallel. We calculate the long-term trajectories of such an organism in a flow, which consists of linear motion in the direction of the vorticity and a conic section in the plane of shear, giving, for instance, helical motion in the case of pure rotation. We compute the orientation probability density function when the reorientation is coupled with rotational diffusion and show that including rotational diffusion reduces the mean swimming speed and rotates the mean equilibrium orientation ...