Slow rupture of viscous films between parallel needles

Experiments and theory on the rupture of a free plane viscous film are reported. The relatively thick film, with a typical thickness of the order of 0.1-0.6 mm, rests between two long parallel needles. When the film is punctured, a hole is formed with the rim on the front. The hole expands, reaches the needles, and propagates along them with a constant velocity of the order of 2-50 cm s-1. The Reynolds numbers for the present experiments are relatively small, 0.002 ≤Re≥0.34. A crude theory for propagation velocity of the rim is proposed; the theory compares well with the experimental data. The rupture profile is visually similar to a U-shaped curve. Crude equations for the rupture profile are derived, and their solutions are consistent with the experimental observations. A theory for propagation velocity and profile of the rupture, applicable to all Reynolds numbers, is proposed. © 2007 Cambridge University Press