Spreading dynamics of three-dimensional droplets by the lattice-Boltzmann method

We have simulated spreading of small droplets on smooth and rough solid sur faces using the three-dimensional lattice-Boltzmann method. We present resu lts for the influence of the initial distance and shape of the drop from th e surface on scaling of droplet radius R as a function of time. For relativ ely flat initial drop shapes our observations are consistent with Tanner's law R similar to t(q), where q = 1/10. For increasingly spherical initial s hapes, the exponent q increases rapidly being above one half for spherical droplets initially just above the surface. As expected, surface roughness s lows down spreading, decreases the final drop radius, and results in irregu lar droplet shape due to pinning of the droplet edge. Our results show that lattice-Boltzmann method can be a powerful tool in realistic simulations o f droplet spreading. (C) 2000 Elsevier Science B.V. All rights reserved.