Recently, terrorism is one of most daunted dangers in the world. Various terrorisms
can come about. Biological and chemical terrors have particularly high mortality rate, and
tend to wreak the secondary disaster. For these reasons, research and development of
measures for decontaminations are emergent and of key issue on a world scale. Sulfur
mustard (HD) is one of chemical agent used to commit terrorism. HD gas has severe toxicity
and long-period damage because of persistent agent. In addition, as HD gas achieves the
toxicity even if it only contacts on a skin, it is important that HD-contaminated objects are
decontaminated quickly. In the present study, HD gas emission from a surface of HD droplet
is numerically researched. HD gas emission is usually investigated with experiments, but the
experiment is so dangerous because of the toxicity. Therefore, in this study, CFD
(computational fluid dynamics) is used to reproduce the emission. We propose a volatilization
model which can estimate the volatilization of a chemical agent with the saturated vapor
pressure of chemical agent and physical quantities of the air. We apply our three dimensional
volatilization prediction code to a HD droplet placed on a wind tunnel wall. Comparing the
numerical results with the experimental data, it is confirmed that the numerical data are in
good agreement with the experimental data. In addition, volatilization volume is coupled with
droplet geometry to simulate the temporal change of droplet shape and residual mass. It is
reasonably predicted that the droplet volume gradually decreases as volatilization proceeds until the droplet disappears.
