Numerical Simulation for the Permeation of Barrier Materials by Neat Liquid Droplets

摘要

A computer simulation for the permeation of neat, non-spreading liquid droplets through barrier materials has been developed. Included in this report is the mathematical formulation of the problem, the numerical method of solution (with copy of computer program appended), and the theoretical results on the effects of barrier thickness, agent solubility, evaporation from the droplet and the upstream surface of the barrier, the invariant contact angle, and the symmetry radius for an array of droplets on the surface of the barrier. A useful analytical expression is then derived for determining the breakthrough time (the time for a given cumulative amount of liquid to permeate through the barrier) as a function of barrier thickness. The diffusivity of diisopropyl methylphosphonate (DIMP) in Neoprene is calculated by comparison of experimental values the breakthrough times for various thicknesses to those predicted using this expression. Keywords: Permeation rate, Computer simulation, Chemical warfare agents, Elastomers, Diffusion coefficient. (mjm)