Multiscale liquid drop impact on wettable and textured surfaces

We present the impact of microscopic liquid droplets on solid surfaces which are flat, or pillared, with either homogeneous interactions or cross-shaped patterns of wettability using numerical simulations. The focus is on relatively low impact velocities leading to spreading or bouncing drops, rather than splashing. Lattice Boltzmann and Molecular dynamics methods are used for nanometer-sized and continuum droplets, respectively, and the results of the two methods are compared in terms of scaled variables. In most situations we find similar droplet behavior at both length scales. The agreements between the methods are reasonable at low impact velocities on wettable surfaces while some discrepancies are observed for strongly hydrophobic surfaces and for higher velocities.