The skating of drops impacting over gas or vapor layers

We report numerical simulations confirming the predictions and scaling relationships deduced in Gordillo and Riboux, JFM 941, A10, 2022. where we elucidated the lubrication mechanism by which a drop of a low viscosity liquid impacting over a smooth solid substrate skates over a thin gas or vapor layer that prevents the contact with the wall. In contrast, our numerical results do not validate the approximate equations given in Mandre and Brenner, JFM 690, 148–172, 2012, who claimed that the minimum thickness of the gas film separating the drop from the substrate is attained when a certain type of self-similar solution, valid right after the impact, can no longer describe the unsteady flow near the wall. Moreover, with the purpose of explaining the so-called lift-off mechanism reported in Kolinski, et al, PRL, 112 (13), 134501, 2014 here we derive expressions for the time-varying thickness of the gas layer at the region where the pressure is maximum, finding that these equations closely follow the numerical results.