Numerical simulations of growth dynamics of breath figures on phase change materials: The effect of accelerated coalescence due to droplet motion

¹ Department of Physics, Fergusson College - Pune 411004, India
² Department of Mechanical Engineering, Birla Institute of Technology and Science Pilani, K K Birla Goa Campus - NH 17B, Zuarinagar, Goa 403726, India
³ Department of Physics, Pillai College of Engineering - New Panvel 410206, India
⁴ Department of Physics, Savitribai Phule Pune University - Pune 411107, India

^(a) nileshp@goa.bits-pilani.ac.in (corresponding author)

Received: 29 March 2021
Accepted: 9 July 2021

Abstract

We present the growth dynamics of breath figures on phase change materials using numerical simulations. We propose a numerical model which accounts for both growth due to condensation and random motion of droplets on the substrate. We call this model as growth and random motion (GRM) model. Our analysis shows that for dynamics of droplet growth without droplet motion, simulation results are in good agreement with well-established theories of growth laws and self-similarity in surface coverage. We report the emergence of a growth law in the coalescence-dominated regime for the droplets growing simultaneously by condensation and droplet motion. The overall growth of breath figures (BF) exhibits four growth regions, namely, initial , intermediate or crossover , coalescence-dominated regime , and no coalescence regime in late time , where and t are the average droplet radius and time, respectively. The power law exponents are , , , and . Moreover, the surface coverage reaches a maximum value where the third growth regime starts. We also demonstrate that during the growth dynamics of BF, the random motion amplitude δ and its probability p(R) linked to the power exponent γ of droplet radius R have a specific limiting range within which its effect is more predominant.