A Fast CFD model Aeolus for simulating flow and dispersion in urban areas and complex terrain

Aeolus is a NARAC developed fast CFD model, which can simulate flow and dispersion in urban areas and can also be used for regions with complex terrain. The model can be run in an operational mode using a Reynolds Averaged Navier-Stokes model and in a detailed and accurate mode using a Large Eddy Simulation model. The model has been extensively evaluated against Joint Urban 2003 continuous releases. Aeolus capabilities are being extended and the model is being used for numerous applications.

Aeolus has been recently used to simulate dense gas release scenarios in various urban areas to prepare planning guidance and assess disaster response capabilities. It was also used to model toxic chemical release scenarios for Georgetown University's Emergency and Disaster Management master's program (a collaborative effort between the university and LLNL).

As a part of this work, we will be performing a validation study for a puff release in an urban area. The release will be modeled as an instantaneous release and 1-minute time averaged concentration at various sensor locations in the urban area will be compared with Joint Urban 2003 field data. Validation results for multiple puff releases will be shown and discussed.

In addition, results will be shown for simulations of pressurized chlorine based on the Mock Urban Obstacle Layouts similar to the planned Jack Rabbit II experiments. Time series of concentration for two different layouts will be compared at various locations along the grid as well as along 1, 2 and 5 km arcs and the sensitivity of concentration to the two layouts will be discussed.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. The Department of Homeland Security sponsored part of the production of this material