DROP IMPACT ON SUPERHYDROPHOBIC SURFACES-VARYING GRAVITATIONAL EFFECTS

We performed in this experimental study impacts of aqueous ferrofluid drops on a superhydrophobic surface. The ferrofluids were used to simulate changes of the gravitational acceleration g(*) by applying different magnetic fields. It has been shown that a rebound/no rebound boundary can be obtained when plotting the impact results as a function of Weber, Reynolds, and Bond numbers, which quantify, respectively, effects of inertia over capillary ones, inertia over viscous dissipation, and gravity over capillary effects. On a We versus Re/Bo(n) graph an optimum value of n close to 4 has been obtained by support vector machine analysis. Conditions to get rebound or no rebound have been established as functions of the impact parameters and of the liquid characteristics, but also of the body forces intensities.