Drop rebounding on heated micro-textured surfaces.

This study investigates the hydrodynamics and heat transfer of a droplet impinging on a heated superhydrophobic surface at low Weber numbers with subsequent bouncing through numerical simulations in the phase-field framework. These structure-resolved simulations take into consideration the entrapment of air during impingement on the micro-textured surface and effectively replicate the hydrodynamic behavior observed in corresponding experimental studies [1]. The simulation results indicate notable differences in air entrainment and heat transfer dynamics for the same contact angle under varying surface topography. This offers the potential to deliberately modify the dynamics of heat transfer by manipulating the surface topography without significantly altering the wetting behavior. Additionally, an attempt to substitute the structure-resolved boundary with a temperature boundary condition, which incorporates the void fraction and thermal conductivity of the involved fluids, has been observed to be insufficient to reproduce the temperature evolution due to the absence of wetting physics description. These findings suggest that the primary source of variations in heat transfer is the alteration in the contact area with the surface, rather than the local thermophysical properties of the air/water mixture. Consequently, for an accurate evaluation of heat transfer on textured surfaces, it is imperative to employ simulations that consider the resolved surface topography. • 3D simulations of droplets on heated surfaces with varying roughness were conducted using phase-field. • Textured surfaces with low roughness improve heat exchange over smooth ones due to larger contact area. • Textured surfaces with high roughness can either enhance or reduce cooling due to their wetting effect. [ABSTRACT FROM AUTHOR]