Fugacity model incorporating computational fluid dynamics for analyzing the behavior of an insecticide sprayed indoors

Fugacity models are used widely to predict the time-dependent behaviors of chemicals in environments containing several media (e.g., air, sediment, soil, and water). However, these fugacity models work on the assumption that the concentration of a chemical in each medium is uniform, so they cannot describe the spatial distribution of the chemical. We developed a new fugacity model, termed InPestCFD, incorporating computational fluid dynamics to describe both the time-dependent distribution and the spatial distribution of a chemical in a medium. InPestCFD was used to calculate the behavior of an insecticide released from an aerosol canister in a room. Indoor airflow and aerosol particle behavior were calculated via computational fluid dynamics and using a Lagrangian dispersion model. Transport of the insecticide among media (aerosol particles, air, ceiling, floor, and walls) was calculated using the fugacity model. The time-dependent distributions and spatial distributions of the insecticide in the media agreed well with real measurements.