Dibyendu Ghosh
Department of Mechanical Engineering, IIT Kharagpur, Kharagpur - 721302, India
Saikat Datta
School of Engineering, University of Edinburgh, Edinburgh EH9 3FB, United Kingdom
Prasanta Kumar Das
Department of Mechanical Engineering, Indian Institute of Technology
Kharagpur, Kharagpur 721302, India
The formation and growth of nanobubbles around a rotating
nanoparticle (NP) suspended in a bulk liquid is studied using
LAMMPS molecular dynamics (MD) package. Initially, the
nanoparticle and the surrounding liquid are at a temperature
lower than the saturation temperature of the bulk liquid at
atmospheric pressure. Due to the rotational motion of the NP,
there is a transfer of energy from the nanoparticle to the
surrounding liquid. Consequently, the temperature of the bulk
liquid rises. Argon is used as the bulk liquid, and Cobalt as the NP for all the simulations performed. The interactions between them, as well as with the two pistons, are modeled using Lennard-Jones potential. The effect of the NP diameter,
wettability of the NP surface, and frequency of rotation of the
NP on the bubble formation and growth is studied. We observe
that with the increase in the nanoparticle surface wettability,
bubble formation takes place faster for 2 nm and 4 nm diameter nanoparticles. For 3 nm diameter nanoparticles, initially, bubble volume increases rapidly with the increase in the surface wettability, but then it slows down when wettability is further increased. If the nanoparticle diameter is increased, keeping the surface wettability and frequency of rotation constant, bubbles form and grow faster due to the increased centrifugal force on the neighboring argon atoms. With the increase in the frequency of rotation, bubbles grow faster up to a particular value of frequency, but after that, an
increase in frequency causes slower bubble growth.