Manipulating drop shapes in a microchannel

We use a boundary-integral algorithm that simulates the motion of a freely suspended, three-dimensional deformable drop in a plane-parallel microchannel at small Reynolds number, large Peclet number, and moderate capillary number. The drop size is comparable to the channel height, which is much smaller than the channel depth. In this problem, the final shape of the drop is extremely dependent on the channel shape, flow ratios and time, so we have studied a variety of conditions. By changing the number of inlet and outlet channels, as well as the physical geometry of the channel and the drop properties, we are able to create a diverse set of droplet shapes, including shapes with interesting geometric properties such as deltoids, dumbbells and oblate spheroids. In principle, desired shapes could subsequently be “frozen” by a temperature-induced or flow-induced phase change, to yield particles with desired geometries and properties for drug delivery, tissue scaffolds, etc. This presentation will describe the simulation method and present example results of how different shapes may be achieved.