Janus particle is nano to micro meter sized entity having two distinct faces, only one of which is chemically or physically active. A class of Janus particle is called active or self-propelled Janus which can move extracting energy from environment by creating concentration or thermal gradient at the vicinity of its active surface. Due to its self-propelled motion we model an active Janus particle carrying a cargo i.e. passive particle to form an active dimer. To use the dimer in different purposes, such as targeted drag (cargo) delivery in medical science, the detailed knowledge about its diffusive properties in presence of hydrodynamic interaction and flow field is necessary. Therefore we study the 3D dynamics of the active dimer suspended in a shear (Couette) flow. Using numerical simulations, we determine the diffusivity of such dimer in the presence of long-range hydrodynamic interactions for different values of its self-propulsion speed and the Couette flow. We observe that the effect of hydrodynamic interactions is greatly enhanced under the condition that self-propulsion is strong enough to contrast the shear flow. The magnitude of the effect grows with the size of the dimer’s constituents relative to their distance, which makes it appreciable under experimental conditions.

Diffusion of Janus particle carrying cargo in a shear flow

ACS Spring 2022

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