Experimental Investigation of the Motion and Deformation of Droplets in Curved Microchannel

The trajectory and topology of an immiscible droplet moving in a microchannel can be influenced by the flow structure or a vortex within the flow. Channel geometry is a common effective parameter of the flow structure. Investigating the effect of a curved channel on the droplet trajectory and topology helps one to understand the effect of such geometries on the content of the droplets in various applications. The effect of Reynolds number, 3.5 ≤ Re ≤ 7, surface tension, and droplet size has been experimentally studied on the droplet shape and trajectory. Droplets were generated from a 2-propanol–water mixture with a broad range of equivalent diameters of 95 μm ≤ deq ≤ 610 μm in two microchannels with a 180° and 270° curvature angle. It was found that lateral migration and deformation of the droplet are insensitive to variations in channel Reynolds number. Surface tension, however, has a direct impact on the deformation of the droplets. It can also affect the trajectory of the droplets and direction of lateral migration. Furthermore, droplet size was shown to significantly affect the deformability of the droplet