Wettability alterations and magnetic field effects on the nucleation of magnetic nanofluids: A molecular dynamics simulation

In this study, the effects of surface wettability and nanoparticle concentration on boiling of ferrofluids were investigated with the application of magnetic field using molecular dynamics simulations. Liquid argon was considered as the base fluid with the use of Lennard-Jones fluid model. Two different surfaces (hydrophilic with contact angle of 40.5° and hydrophobic with contact angle of 130.6°) were taken into consideration to investigate the effect of nanoparticle presence on bubble formation over a uniformly heated wall. According to the obtained results, vapor film formation and nucleation depend on the interfacial wettability of nanoparticles and substrate. Compared to the pure liquid, film boiling does not easily happen in the ferrofluid containing hydrophilic nanoparticles, while it is easy to have vapor film in the nanofluid with hydrophobic nanoparticles. It was found that the momentum change due to external magnetic field dramatically alters the evaporation mechanism, resulting in lower liquid film temperature.