A validation of large eddy simulation for complex urban environments

The use of large eddy simulation is becoming an important assessment tool in the field of atmospheric transport and dispersion in urban environments. This paper describes a massively parallel building airflow model which will eventually be able to investigate scale interactions of more than two orders of magnitudes. These scale interactions range from those of the typical feature on a building $O(2)$ meters to a larger horizontal extent of many buildings and a vertical extent that extends to the atmospheric boundary layer height. The model has an advanced finite element construction which allows complex geometrical configurations to be modeled. Simulations will be presented which compare well with an EPA wind tunnel experiment involving rows of rectangular blocks. Once, confidence in the model has been established, dispersion simulations will be presented for much more complex urban geometries involving O(100) real buildings. This is made possible through the use of an innovative mesh generation technique.