We report the results of simulations of rigid colloidal helices suspended in a shear flow, using dissipative particle dynamics for a coarse-grained representation of the suspending fluid, as well as deterministic trajectories of non-Brownian helices calculated from the resistance tensor derived under the slender-body approximation. The shear flow produces nonuniform rotation of the helices, similarly to other high aspect ratio particles, such that more elongated helices spend more time aligned with the fluid velocity. We introduce a geometric effective aspect ratio calculated directly from the helix geometry and a dynamical effective aspect ratio derived from the trajectories of the particles and find that the two effective aspect ratios are approximately equal over the entire parameter range tested. We also describe observed transient deflections of the helical axis into the vorticity direction that can occur when the helix is rotating through the gradient direction and that depend on the rotation of the helix about its axis.

中文翻译：

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剪切流中螺旋的有效长宽比。

我们报告了在剪切流中悬浮的刚性胶体螺旋的模拟结果，使用了耗散的颗粒动力学来表示悬浮液的粗粒度表示，以及根据细长条件下的阻力张量计算出的非布朗螺旋的确定性轨迹-身体近似。类似于其他高长宽比的粒子，剪切流会导致螺旋线的旋转不均匀，从而使更多的细长螺旋线花费更多的时间与流体速度对齐。我们介绍了直接从螺旋几何中计算出的几何有效长宽比，以及从粒子轨迹中得出的动态有效长宽比，发现这两个有效长宽比在测试的整个参数范围内大致相等。