A Fast-Running Urban Airflow Model

A fast-running urban airflow model, RUSTIC (Realistic Urban Spread and Transport of Intrusive Contaminants), has been developed to fill a gap between CFD and mass-consistent flow models. To simplify computation the continuity and thermodynamic equations are combined into a single pressure tendency equation. RUSTIC also includes a k-w turbulence model, and atmospheric stability effects.

RUSTIC uses a modified Cartesian grid structure and the solution is obtained using the finite-volume technique. An automated grid generation routine is available for generating grids from a variety of terrain and building model data files.

Comparisons with wind tunnel data show that RUSTIC is capable of performing as well as more complex models. A technique for running RUSTIC with several different grids of increasing finer resolution is being developed with the goal of providing rapid convergence to a “useful” solution within as short of a period of time as possible.