Coating of bilayer thin liquid films on rotating cylinders

Motivated by the need to improve fundamental understanding of multilayer coating on discrete objects, we consider a model problem involving the flow of bilayer thin liquid films on rotating cylinders. A parametric study reveals that the critical rotation rate required to cause motion of liquid lobes that form due to gravitational drainage is lowered for a more viscous and thicker inner film due to an increase in viscous forces. These properties of the inner layer also lead to a reduction in the amplitude of temporal oscillations in the film thickness. In addition to advancing fundamental understanding, we suggest strategies for improving the uniformity of coatings on discrete objects.