Growth of Cloud Droplets by Condensation: A Problem in Computational Stability

Abstract

This article deals with the computational stability of numerical techniques for solving the equations governing droplet growth by condensation. A numerical analysis leads to the derivation of a simple stability criterion for determining a permissible time step in the integration of these equations. The time step is inversely proportional to the product of the total number of droplets and their mean radius. This criterion is generally valid except near the activation stage where a less simple one applies. The practical importance of these criteria for the feasibility of running complex simulation experiments is emphasized.