Air quality as well as dispersion of biological and chemical contaminants within urban and industrial areas is strongly influenced by building clusters that perturb local winds. Although air circulation and turbulence in the vicinity of a single building, a few buildings or sparsely located buildings have been studied extensively, only a few studies exists on detailed flow patterns within and surrounding a building cluster. Yet, such details are of great importance in predicting the dispersion of material from sources located near the buildings or concentrations of material advected past buildings. Equally important are the pathways of contaminants. In order to address such issues, an experimental program was conducted at the U.S. Army Dugway Proving Ground, dubbed the Mock Urban Setting Test (MUST), in which the authors were participants. The goal of the test was to investigate the characteristics of flow through an urban building cluster and to gather dispersion data of utility in evaluating and developing urban dispersion models. The MUST set up consisted of a 180m x 176m rectangular array of 120 containers that simulated an urban environment, and the natural background flow was allowed to pass through this simulated urban cluster.

Balloons carrying tethersondes were vertically traversed at a site 420m northeast of the center of the building cluster, which provided background profiles of important meteorological quantities. Sonic anemometers located at the southern (upwind) side of the grid as well as in the first urban canyon provided mean and turbulent characteristics of the flow. Thermistors provided temperature profiles in the upwind side, in the vicinity of the ground. Plan index area of the experimental array was 0.14, and the flow regime was near the boundary between isolated roughness and wake interference regimes of Hussain & Lee classification.

The flow in and around the same building configuration was also investigated using a numerical model that employs a conventional turbulent kinetic energy - dissipation (k-e) closure scheme. The calculated streamlines, mean flow, temperature structure and turbulent kinetic energy are being compared with those obtained during the experimental program.