Computer Analysis of the Growth of a Cloud Drop by Coalescence.
Abstract
Over a four year period, from September 1967 to July 1971, the rate of growth of a 30 micron radius drop to 50 or 100 micron radius by a process known as accretion has been studied as part of the numerical modeling effort of Project Themis. A mathematical model was derived which considers a single 30 micron radius drop falling at its terminal velocity through a field of smaller, 5 to 20 micron radius droplets, and growing by colliding and coalescing with droplets in its path. The droplets also fall at their terminal velocities and the rate of growth of the drop is proportional to the difference in the terminal velocities of the colliding drop and droplet as well as the area of sweep of the falling drop and the number of collectible droplets per unit volume of cloud. Hydrodynamic and electrostatic forces influence the rate ofgrowth and are accounted for by introduction of a 'collision efficiency' term to the analysis. Electrical forces also influence the terminal settling velocities of the particles, so Stoke's law of drag on a sphere and the intermediate law were derived incorporating these forces.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1971
- Accession Number
- ADA072464
Entities
People
- Ralph C. Huntsinger
Organizations
- South Dakota School of Mines and Technology