Evaluation of FLACS CFD model with MUST data

FLACS is a CFD model that has been developed to simulate flow and dispersion of hazardous gases in the atmosphere. It reduces the model run time by using larger-than-usual grid volumes where the porosity of the obstacles within each volume is defined. Results of its evaluation with the Mock Urban Setting Test (MUST) data are shown. The MUST experiment involved 120 shipping containers (2.4 m wide by 2.5 m high by 12.2 m long) installed in a rectangular array on the desert floor at Dugway Proving Ground, Utah. There were 37 tracer release trials analyzed, with monitors on four downwind arcs within the array. In general, about 65 % of the FLACS predictions of arc maximum concentration are within a factor of two of the observations, and there is about a 30 % mean underprediction bias.