Molecular dynamics study about the effects of random surface roughness on nanoscale boiling process

The boiling process of argon above solid copper substrates with different surface roughness levels are investigated using molecular dynamics simulations. The randomly distributed rough surface profiles are generated by a multivariable Weierstrass-Mandelbrot function. With the application of the thermostat on the solid atoms, bubble nucleated at the solid-liquid interface after experiencing a period of evaporation process. Afterwards, the bubble grew into vapor film and pushed the bulk liquid cluster away from the solid wall. It was found that the rough structures advanced the boiling inception time and increased the evaporation mass flux. The existence of cavities is favorable for bubble nuclei appearance. Besides, the heat transfer between the solid and fluid atoms become more efficient with the help of surface nanostructures. The energy exchange rate is further improved with higher surface roughness.