Interaction of active droplets with channel wall

In an active octane-in-water emulsion, droplets can move independently due to the Marangoni flow. The non-uniform distribution of surface tension on the droplet surface is caused by the diffusion of ammonia from the aqueous emulsion solution into the octane droplets. Here, we analyze the influence of the channel wall on the motion of active droplets. The results of the study show that, depending on the average droplet velocity in the emulsion, two cases can occur. In one, the moving droplets adhere to the channel wall. This case occurs when the average velocity of the active droplets is less than a certain critical value. However, if the average velocity of the droplets exceeds this value, the active droplets do not adhere to the wall. A boundary layer forms along the channel wall. In this layer, the velocity of the droplet decreases toward the wall.