Aggregation by persistent diffusion

The growth of liquid clusters in a vapor near condensation is investigated. The dynamic density profile is derived from the transport equation for the distribution of velocity and position of particles which diffuse in the local chemical potential of the cluster but show a tendency to persist along the classical path. For early growth, the model displays both growing and shrinking clusters depending not on their size as in Ostwald ripening but on the excess or lack of particles in the neighborhood of the cluster. The generation of growing clusters is found to be more likely and the probability to observe a cluster of a given size counts the number of clusters that reach that size by either growth or decay.