Abstract
This project has made new findings regarding the role of computational fluid dynamics (CFD) in understanding flow and dispersion. This portfolio of new results arising from the application of CFD methods to atmospheric flows on process plants has increased the confidence that can be put in CFD to model certain classes of atmospheric flows. Using comparisons of results to full scale and wind tunnel measurements, it was found that CFD provides numerous benefits over other approaches, although an appreciation of its limitations when applied to atmospheric modelling is required. Key issues when using CFD have been investigated, in particular those arising when modelling atmospheric flow and dispersion. This has also led to the discovery of situations and flows where CFD methods are not appropriate. A method for modelling a congested region as a volume of homogenous porosity has been developed, and with reference to full scale measurements, we found that this method can reliably reduce the complexity of a problem. We have found that CFD can fill gaps in our understanding of atmospheric flow and dispersion, and in applications involving their prediction. It can complement and supplement full-scale and wind- tunnel scale experiments, and in some situations it can provide an alternative. It can guide and validate the use of simpler models and inform experimental and theoretical work required to develop simpler models. New, more accurate and efficient methods of hazard assessment have been developed and demonstrated. The role of CFD in these new approaches is now clear. Improvements to the health, safety and environmental performance of gas, oil and chemicals companies can be realized from this work by - Guiding and validating full scale measurement strategies and improving the interpretation of this data into emission fluxes - Guiding the use of simpler models that are necessary for risk assessments of hazardous gas concentrations - Using the new explosion hazard assessment methods that have been pioneered, which are designed to assess both likelihood and severity - Using the new CFD technique that has been developed for screening out 'hazardous' plant designs, which strikes a balance between oversimplification and unfeasible levels of detail.