Analysis of velocity fields and dispersive cavity parameters as a function of building width to building height ratio using a 3-D computer model for squat buildings

The objectives of this work were to show that a three-dimensional turbulent kinetic energy/dissipation (k–ε) computational model, FLUENT, can be used to facilitate modeling of fluid flow fields with stack geometry generated by a variety of building shapes, and to use the data sets to develop parameterizations useful to air quality modeling needs. Once the usefulness of the computational model was proven through comparisons with experimental results, and data generated for several ratios of building width to building heights, the flow field was examined to determine the length of the recirculation cavity as a function of the ratio of building width to building height both in front of and in the rear of the building. The dimensions of the recirculation cavity in the front of the building have previously not been included in regulatory models, so both the height and length of this front recirculation cavity were parameterized as a function of the ratio of building width to building height. The maximum of value downdraft was also parameterized as a function of the building width to building height ratio. Although FLUENT is less than a perfect match for all measured parameters in all parts of the flow field, it does reveal the areas of greatest variability (and hence interest) and will be a useful way to efficiently take the limited measurements for development and confirmation of future model improvements.