Growth dynamics of breath figures on phase change materials: a numerical study

We present a numerical investigation of the effect of droplet motion on the growth dynamics of breath figures during condensation on phase change material. Breath figures are a micro-scale pattern of droplets that form when droplets condense on a cold surface. The numerical model considers the growth of droplets due to condensation, droplet coalescence, random droplet movement, and surface wettability. We study the dynamics of breath figures in terms of the time of evolution of the mean radius of droplets {R}, surface coverage epsilon(2), and the droplet size distribution ns. We demonstrate that the droplets' movement significantly changes the distribution of droplets condensing on a phase change material by increasing coalescence. We observed four growth regimes on phase change materials due to the movement of droplets. First, in the initial regime, {R} similar to t(alpha 1), intermediate regime {R} similar to t(alpha 2), coalescence-dominated regime {R} similar to t(alpha 3), and late regime {R} similar to t(alpha 4). The growth exponents are alpha(1) approximate to 1/2, alpha(2) approximate to 1(alpha 3), and alpha(4) - 1/3. While the growth exponent alpha 3 depends on the contact angle of the surface.. Furthermore, we show the scaling of the droplet size distributions at different times.

Automated summary

This study numerically investigates the influence of droplet motion on the growth dynamics of breath figures during condensation on phase change material. The model considers aspects such as condensation, droplet coalescence, random droplet movement, and surface wettability. The dynamics of breath figures are analyzed in terms of the evolution of droplet mean radius, surface coverage, and droplet size distribution. The results demonstrate that droplet movement significantly alters the distribution of droplets on the phase change material, mainly through increased coalescence. Four growth regimes are observed, characterized by different power-law relationships between droplet radius and time.