Study of Microdroplet Growth on Homogeneous and Patterned Surfaces Using Lattice Boltzmann Modeling

Abstract

We present droplet growth dynamics on homogeneous and patterned surfaces (surface with hydrophilic and hydrophobic region) using two-dimensional thermal lattice Boltzmann method (LBM). In the first part, we performed 2D simulations on homogeneous hydrophobic surfaces. The result shows that the droplet grows at higher rate on a surface with higher wettability which is attributed to low conduction resistance and high solid–liquid contact area. In the later part, we performed simulations on patterned surface and observed that droplet preferentially nucleates on the hydrophilic region due to lower energy barrier and grows in constant contact line (CCL) mode because of contact line pinning at the interface of hydrophilic–hydrophobic region. As the contact angle reaches the maximum value of hydrophobic surface, contact line depins and droplet shows constant contact angle (CCA) growth mode. We also discuss the effect of characteristic width of hydrophilic region on growth of droplet. We show that contact angle of the droplet increases rapidly and reaches the contact angle of hydrophobic region on a surface with a lower width of the hydrophilic surface.