Numerical study of Leidenfrost effect suppression on structured thermal pillars using a lattice Boltzmann method

A three-dimensional pseudopotential central moments lattice Boltzmann method, coupled with a fourth-order Runge–Kutta scheme for the temperature field, is employed to study the impact of Leidenfrost droplets on overheated structured thermal pillar surfaces. The numerical method is validated through simulations of liquid–vapour phase-change processes and dynamic impingement of Leidenfrost droplet on overheated walls. A parametric study varying surface temperature, droplet inertia, and pillar dimensions provides insights into droplet dynamics and Leidenfrost point (LFP). Results demonstrate that structured thermal pillars significantly elevate the LFP compared to flat surfaces by enhancing vapour flow beneath the droplet. Detailed analyses reveal that increasing surface temperature promotes the Leidenfrost phenomenon, while droplet inertia affects the rebound height but not LFP, resulting in a lower average vaporisation rate when Leidenfrost effect happens. Furthermore, the influence of pillar dimensions on the LFP is explored by establishing phase diagrams of the Jacob number (Ja) against pillar width, height, and spatial distribution. The results indicate that narrower and taller pillars are more advantageous in suppressing the Leidenfrost effect. When the pillar height exceeds 40% of the droplet radius, the suppression effect diminishes. Moreover, increasing the number of pillars, resulting in smaller tunnel and pillar widths, tends to enhance the Leidenfrost effect.