Effect of Poiseuille flow on the dynamics of active vesicle

The influence of an external flow on the dynamics of active deformable particles demands a detailed understanding of the involved mechanism due to their prominent applications in medical and industrial fields. In this regard, we have investigated the effect of an external Poiseuille flow on the motion of an active deformable vesicle using a hybrid coarse-grained computational method. The activity of the vesicle is maintained through the concentration gradient of the solvent across its surface. Such a deformable active object, when exposed to the Poiseuille flow, exhibits a range of dynamical modes, which are greatly influenced by the size of the vesicle. For smaller external flow strength, we have observed the competition between propulsion force and external flow for various vesicle sizes. An interesting tank-treading motion is found for stronger flow strength in the case of a large vesicle. With appropriate physical quantification, we have explained that the key factors affecting the translational and rotational motions of the vesicle are its surface fluidity and its resistance to the external flow.