Measurement and Prediction of Particulate Concentration Within External and Internal Flows

The focus of this report is the formation, growth, and transport of airborne particulate clouds within the boundary layer atmosphere as well as the interaction of such clouds with the terrain surface and objects (e.g., ships and buildings) on the earth's surface. The methodology outlined in the report can be used to answer the simple question, 'What happens to particulate clouds once they are formed?' The specific particulate subjected to detailed analysis was a millimeter-wave (mmw) obscurant. A novel concentration measurement device (a type of interferometer) applicable to this class of obscurants was used to collect data during a dissemination field test. The experimental data compared favorably to external flow predictions resulting from the Transport, Diffusion, and Radiance (TDR) computer code, interim version 3.2. TDR is based on Gaussian statistics with high fidelity physical assumptions governing the behavior of puffs and plumes. Predictions were also made of internal room contamination caused by the ingestion of a particulate cloud by a notional, ventilated building. This analysis employed the Ship Chemical Warfare Vulnerability Ventilation Model (VENM). Time-dependent concentration, exposure, and deposition histories were calculated and graphically rendered for the mmw obscurant cloud. Parameters that significantly impact the TDR predictions for these quantities were varied as part of a sensitivity analysis. Limitations in particulate concentration measurement accuracy are discussed in an overall sense and are related to predictions resulting from both Gaussian and computational fluid dynamics (CFD) models. Suggestions are provided as to when Gaussian and when CFD modeling approaches are warranted.Naval Surface Warfare Center Dahlgren Div VA is the author of 'Measurement and Prediction of Particulate Concentration Within External and Internal Flows', published 1997 under ISBN 9781423547648 and ISBN 1423547640.