Development of a High Fidelity PC Based Simulator for Modeling the Atmospheric Transport and Dispersion of Nuclear, Chemical, Biological, and Radiolog

A simulation tool is proposed to model and simulate the wind fields, turbulence fields, and the unsteady dispersion of NCBR substances in urban areas on the building to city blocks scale. This Computational Fluid Dynamics (CFD)-based approach has beenshown to accurately simulate the urban wind and turbulence fields with minimal approximations, and has been demonstrated by modeling the flow fields and simulated release of CBW agent near the White House and in a region of Salt Lake City. This UrbanDispersion Simulator (UDS) utilizes recent advances in modern CFD algorithms, uses an automated model setup via a unique image-based approach, and is driven by an intuitive interface. Based upon the very positive results of the Phase I study, a number ofphysical modeling, speed and interface enhancements are proposed. These include modeling buoyancy, solar radiation, tree-induced flow losses, HVAC effects, and the dispersal of gas-phase agents as well as solid and liquid dispersants. The simulator willprovide rapid simulation turnaround times by remotely distributed parallel processing, solution-adaptive mesh refinement and other algorithm refinements for unsteady dispersal calculations. A Common Object Request Broker Architecture (CORBA) implementationof the UDS interface will be developed to allow the UDS laptop-based front-end the transparent access of a remotely distributed compute server by wireless or wired connection. Provision for direct import of a variety of CAD formats, such DXF and VRML, willbe made. Careful validation studies of important experimental and urban wind fields and dispersion will be made to archive the effects of different wind and turbulence profiles upon the solution quality. The developed capability and software (UrbanDispersion Simulator, UDS) will be of immediate use for DTRA and many affiliated agencies and contractors. UDS will be beneficial to such Government agencies as the FBI, CIA and Secret Service. Hazardous Material Teams (HAZMAT) will benefit by predictinghazardous plume development in urban areas, and Civilian building architects could assess the wind fields and dispersion characteristics in cities to meet currently mandated regulations.