Figure 1
From: Re-entrant bimodality in spheroidal chiral swimmers in shear flow
(a) Sample spheroidal self-propelled particle with major and minor axes of lengths a and b swimming downstream (i.e., with an orientation vector p making an angle \(-\pi \mathrm{/2} < \theta < \pi \mathrm{/2}\) with the positive horizontal axis) near the top wall of a channel subjected to an imposed Couette flow. The swimmers are chiral, with angular speeds Ω with both levogyre and dextrogyre chiralities (\({\rm{\Omega }} > 0\) or <0, respectively) permitted. The torque from flow (always clockwise in the current settings) acting on the active particles is shown as τ f ; (b) For a given imposed shear, there are two angular speeds at which a fraction of downstream-swimming (majority) chiral particles flip their swimming direction to upstream, leading to the emergence of a minority population. At a smaller angular speed (right schematic), the conversion is dominated by imposed shear, and at a larger angular speed (left schematic), chirality overtakes the effect of imposed shear, and leads to a second population splitting, marking re-entrant bimodality of the active suspension.
