Numerical Simulation of Stationary Nucleation Taking Into Account Thermal Effects in a Wide Range of Supersaturations

The problem of stationary vapor–liquid nucleation with a constant number of particles interacting via the Lennard-Jones potential is solved by the molecular dynamics method for both isothermal and non-isothermal nucleation, over a wide range of vapor supersaturations. A special simulation approach is used, in which clusters that reach a certain size are removed from the system, and their particles are returned as monomers. The temperature distribution over cluster sizes is determined. It is found that the temperature, starting from the monomer level, decreases somewhat but as the cluster size approaches the critical value, returns to its initial level and then increases rapidly. This temperature distribution over cluster sizes governs the distribution of their number densities, controlling the vapor non-ideality and significantly affecting the nucleation rate. The critical importance of knowing the cluster temperature for analytical models is demonstrated, as it enables accurate determination of vapor supersaturation and the actual non-isothermal nucleation rate. The nucleation rates and critical cluster sizes obtained for the isothermal and non-isothermal cases show satisfactory agreement with a theoretical model predicting a decrease in the nucleation rate under non-isothermal conditions.