A numerical study on the dynamic behavior of the liquid droplet located on heterogeneous surface

Abstract

The behavior of a droplet located on a heterogeneous surface is numerically analyzed using the 3-D Lattice Boltzmann Method. Predictions are made whether the droplet will be separated or not and the separation time is calculated changing the contact angles of the hydrophilic surface, hydrophobic surface and the area of the hydrophobic surface. The change in the contacting length between the droplet and the bottom surface and the change in the dynamic contact angle of the droplet on the cross section at the center of the droplet as time passes are observed, and the droplet separation mechanism is investigated by analyzing the velocity vector around the phase boundary line and the droplet which changes with time while the shape of the droplet changes. A droplet located at the center of a heterogeneous surface shows a trend of being easily separated if the difference between the contact angles of the hydrophilic and hydrophobic surfaces is bigger. The more the contact angle of the hydrophilic surface increases, the more the droplet separation time increases, and the more the contact angle of the hydrophobic surface increases, the more the droplet separation time decreases. Also, though the droplet separation time shows a decreasing trend when the width of the hydrophobic surface increases, it does not have any effect on whether the droplet will be separated or not.