Numerical study of droplets impacting on flat and cone-arrayed surfaces

The dynamic behaviour of droplets impacting on both flat and cone-arrayed microstructural surfaces is investigated using an improved colour-gradient lattice Boltzmann method. We first study the effect of the Reynolds number (Re) on the dynamic behaviour of the impacting droplet by fixing the Weber number (We) at 10. As Re increases, the maximum dimensionless mass centroid of the droplet (z_cmax^∗) for the droplet impact on a cone-arrayed surface is first larger and then smaller than that on a flat surface, indicating that the cone-arrayed surface changes from promoting to preventing the rebound of the droplet from the solid surface. Next, the effect of We on the dynamic behaviour of the impacting droplet is studied by fixing Re=350. For the droplet impact on a flat surface, z_cmax^∗ first increases and then decreases with increasing We, and its maximum value is reached near We=20. For the droplet impact on a cone-arrayed surface, z_cmax^∗ monotonically decreases with increasing We. Finally, the study concludes with phase diagrams that illustrate how the droplet rebound patterns and maximum rebound height vary with Re and We, providing valuable insights for optimizing textured surface designs in applications requiring precise droplet control.