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

Abstract

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 ($\mathrm{We}$) at 10. As $Re$ increases, the maximum dimensionless mass centroid of the droplet (${z_{\mathrm{cmax}}}^{\ast }$) 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 $\mathrm{We}$ on the dynamic behaviour of the impacting droplet is studied by fixing $Re=350$. For the droplet impact on a flat surface, ${z_{\mathrm{cmax}}}^{\ast }$ first increases and then decreases with increasing $\mathrm{We}$, and its maximum value is reached near $\mathrm{We}=20$. For the droplet impact on a cone-arrayed surface, ${z_{\mathrm{cmax}}}^{\ast }$ monotonically decreases with increasing $\mathrm{We}$. Finally, the study concludes with phase diagrams that illustrate how the droplet rebound patterns and maximum rebound height vary with $Re$ and $\mathrm{We}$, providing valuable insights for optimizing textured surface designs in applications requiring precise droplet control.