Sensitivity Analysis of an Instantaneous Box Release Model with Surface Heat Transfer

摘要

Sensitivity analysis was performed to determine the influence of input variables on the results of an instantaneous box release model developed, incorporating the effect of ground heating on the movement of a cloud. The model considered instantaneous release of heavy gases in the presence of wind. It also varied in its approach to the phenomenon of air entrainment, which was assumed proportional to the cloud frontal velocity. A quasi-analytical solution for the equations describing the model was formulated based on standard box model assumptions. The semi-analytical equations developed were then solved by numerical methods to provide a heavy gas cloud dispersion profile. The popular Runge-Kutta Fourth Order technique was adopted to solve the differential equations numerically. The ASTM method (1994) was followed to perform sensitivity analysis for a heated source. The study did not yield Type IV sensitivity to any particular input parameter that would have invalidated model results. Most variables exhibited Type III behavior toward the input parameters.