On the neutralization of bacterial spores in post-detonation flows

Abstract

In multiple operational scenarios, explosive charges are used to neutralize confined or unconfined stores of bacterial spores. The spore destruction is achieved by post-detonation combustion and mixing of hot detonation product gases with the ambient flow and spore clouds. In this work, blast wave interaction with bacterial spore clouds and the effect of post-detonation combustion on spore neutralization are investigated using numerical simulations. Spherical explosive charges (radius, $R_\mathrm{C}$ = 5.9 cm) comprising of nitromethane are modeled in the vicinity of a spore cloud, and the spore kill in the post-detonation flow is quantified. The effect of the mass of the spores and the initial distance, $d^0$, of the spore cloud from the explosive charge on the percentage of spores neutralized is investigated. When the spores are initially placed within a distance of 3.0$R_\mathrm{C}$, within 0.1 ms after detonation of the charge, all the spores are neutralized by the blast wave and the hot detonation product gases. In contrast, almost all the spores survived the explosion when $d^0$ is greater than 8.0$R_\mathrm{C}$. The percentage of intact spores varied from 0 to 100 for 3.0$R_\mathrm{C}$ $<d^0<$ 8.0$R_\mathrm{C}$ with spore neutralization dependent on time spent by the spores in the post-detonation mixing/combustion zone.