Molecular dynamics study of nanodroplets: Initial compressed phase of collisions against a flat wall

Collisions of spherical nanodroplets against a flat wall are studied using molecular dynamics simulations. The initial compressed phase of the collisions is focused on to illuminate the elastic behavior of the droplet. The normal forces F z between the droplet and the wall are calculated at varying impact velocities u along the z-direction and fitted to a power law of the form F z ∝ ξ n , where ξ denotes a deformation. If u is less than 0.2 and ξ < 0.8, then the normal forces all together satisfy a power law with exponent n ≈ 1.5, corresponding to the Hertz law. However, if u is greater than 0.3, then the exponent n changes to around 2.0 ∼ 2.4.