In this experimental work, a two-dimensional (wedge) and three-dimensional solids (conus, 4 and 6-sided pyramids) with different deadrise angles (1– 5^) impact a deep liquid pool (distilled water or 2. 5 % butanol–water solution) at a speed varying from 0. 50 to 19. 75 cm s −1. Below a limit speed dependent on the deadrise angle, ‘exotic’ terminal forms of air entrapment are observed: a large central bubble, two parallel lines of bubbles for the two-dimensional solid, a trail of bubbles, necklace of bubbles, doughnut-shaped bubble and large central bubble for the three-dimensional solids. Above this limit speed, the collapse of the air film forms a line of bubbles near the central edge for the two-dimensional solid, and one/multiple bubbles near the vertex for the three-dimensional solids. The entrapment dynamic is observed using a high-speed camera with a total internal reflection set-up. The outer border of the wetted area expands linearly in time, with a speed that agrees with Wagner’s theory for wedge and conus, which provides the lower and upper limites for genuinely three-dimensional cases (pyramids). The decrease in the size of the air film over time is exponential. The measured initial characteristic size of the air film is proportional to the air dynamic viscosity and inversely proportional to the liquid density, impact velocity and squared deadrise angle, as expected from an air–water lubrication–inertia balance. The prefactor in the scaling law depends on the shape of the solid with a slight but detectable effect of liquid surface tension on its value.
Carrat et al. (Wed,) studied this question.