A Method for Modeling Sub-Grid Combustion in a Large-Scale Wildland Fire CFD Model

The chemical processes of wildland fire combustion are extremely complex, and occur at scales that are orders of magnitude smaller than the scales typically used to resolve the fluid dynamics, especially for large fires. The treatment of fire chemistry in HIGRAD/FIRETEC (a large-scale CFD fire model) can be improved by using a mixture fraction approach. However, this requires the development of a sub-grid model due to the issue of scale. The application of the mixture fraction approach combined with a sub-grid model for gas phase wildland fire combustion will be discussed.