Fractal dewetting of a viscous adhesive film between separating parallel plates

A dewetting cylindrical film between two separating plates is observed to produce fractal finger patterns that penetrate radially inward. In lieu of the classical tip splitting, this fractal is generated by successive shielding of alternating fingers. By analyzing this key shielding dynamics via a forced two-dimensional Hele–Shaw model with global force balance, a self-similar scaling for the shielding distance and shielding time were obtained for every generation of shielding events. The theory predicts that the plate detach time is reduced by a factor of 12 due to the fractal fingers. This is confirmed experimentally for large Bond numbers when there are sufficient fingers to justify a continuum approximation in the theory. A cumulative node number density, which is not a power law, is also predicted but not confirmed experimentally.