Key outcomes

  • Government regulations satisfied
  • Community concerns addressed

Air quality is a serious health concern for many residents in built up environments.  The opening of new industrial sites, or the expansion of existing facilities can raise serious questions regarding the health and odour impacts on the surrounding environment. Addressing these concerns can be an essential part of receiving approval from local councils or regulatory bodies before a project is allowed to be completed.

Traditional plume dispersion models such as AERMOD and its predecessor AUSPLUME are incapable of accurately resolving downwash and building effects that are common places occurrences with small stacks in heavily populated areas. CFD provides a more rigorous, and accurate solution for these cases, and can be used to determine if a facility is acceptable from both a safety and odour point of view. Should CFD modelling show that a facility is not acceptable, it can be used to determine the required level of filtration, or stack changes that will result in an acceptable outcome.

Simulated plume dispersion for a 0.4m/s wind speed from CFD model

Figure 1: Modelled dispersion of the plumes from a pair of stacks.

In the case shown here, Synergetics was approached to perform an assessment on emission from a proposed facility near residential facilities. High level CFD was performed to determine the worst case weather conditions that would result in maximum ground level and façade concentrations for surrounding buildings. These concentrations were then compared to toxicity and odour thresholds, and presented to the local authorities. The CFD results were a critical component of reducing community concerns, and resulted in the facility gaining approval to operate at the site.

CFD simulated ground level concentrations

Figure 2: Simulated dillution factor at ground level under worst case weather conditions. The contours are set so that a value of 8.4 (red) corresponds to an odour that 50% of people will find offensive.