We discuss the thermodynamics behind self-organizing Benzoquinone (BQ) particles on air–water interface. Experiments (Satterwhite-Warden et al., 2015; Chen et al., 2019; Satterwhite-Warden et al., 2019) reveal that BQ particles undergo rapid transient flocking behavior as they move around on the liquid surface. Flocks are seen to vary in size and their formation and stability appears to be dependent upon their shape. It is hypothesized that self organization of particles is a result of surface tension gradients in the two dimensional liquid surface resulting from the slow dissolution of the BQ particles. The current paper uses a mass-action kinetic framework to study the flocking of particles. Two dynamical models, with and without a reservoir, are proposed and analyzed through the thermodynamic lens of free energy, which informs us about dominant and spontaneous ‘reactions’ or flock formations in the system. Results of the model are in good agreement with experiment, revealing that irregular shaped BQ particles do indeed show far greater propensity to form flocks compared with regularly shaped particles and validating the mass-action framework as an appropriate tool to investigate this system.
|Communications in Nonlinear Science and Numerical Simulation
|Published - Mar 2022
- Free energy