Introduction

Wind studies of plumes emitted from chimney stacks were begun initially to study the provision of artificial draught for combustion processes. Now with the increased environmental awareness it is recognised that industries that produce atmospheric waste are required to meet strict environmental criteria. Designers are now potentially liable for harm brought about by excessive pollutant concentrations due to unsatisfactory building or site layout.

Common applications of this type of study include :

  • The study of the propagation of odour from sources such as sewerage effluent, treatment ponds and chemical wastes.
  • The dispersion of smoke from power generators using coal fuel.
  • The dispersion of air pollution emitted from vehicle exhausts (eg. a new bus stand or a proposed freeway).
  • The re-entry of air-conditioning exhaust into the system, potentially leading to the fatal Legionnaires disease.

Methodology

Depending on the nature and scale of the study, the dispersion patterns of the atmospheric pollutant can be modelled either mathematically or physically. Physical modelling, involving the use of the wind tunnel can be conducted using either visual techniques or through a quantitative analysis by measuring concentrations of a trace gas at a number of critical locations.