Molecular dynamics simulations of sessile and pendant droplets' shape on inclined and curved surfaces

Abstract

In this study, shape of water droplets with different sizes on various inclined smooth surfaces is simulated numerically and advancing and receding contact angles are determined by using the molecular dynamics approach. Experimental measurements are also carried out to validate the numerical predictions of droplet shape on inclined surfaces. Based on the verified code, shape of water droplets in different sizes around smooth circular cylinders with various diameters is simulated. Furthermore, advancing and receding contact angles along with the hysteresis values of the sessile and pendant droplets with various sizes around the cylinders are evaluated. Finally, based on the numerical results, two correlations are developed to predict advancing and receding contact angles of droplets on the circular cylinders. According to the results, maximum advancing and minimum receding angles take place on both sides of the cylinder on a horizontal line passes through the cylinder center. As a result, contact angle hysteresis reaches its maximum value in these two positions. In addition, advancing and receding angles have the same values on the top and bottom of the cylinder. Moreover, droplet size and cylinder diameter have minor effect while drop position has major effect on the shape of droplets over the cylinder.