A review of fire whirls in wildland fires

Abstract

Fire whirls have long fascinated the research community, however their destructive power has hidden many features of their formation, growth and propagation. Most of what is known about fire whirls, therefore, comes from scale modeling experiments in the laboratory. Both the methods of formation, dominated by wind and geometry, and the inner structure of the whirl, including velocity and temperature fields, have been studied at this scale. The particular case of quasi-steady fire whirls directly over a fuel source forms the bulk of current experimental knowledge, despite many other cases existing in nature. This presentation will review the state of knowledge concerning the fluid dynamics of fire whirls, including the conditions for their formation, their structure and the mechanisms which control their unique state. Particular emphasis will be given to the formation of fire whirls during wildland fires, especially during extreme fire events. Finally, recent discoveries will be highlighted as well as potential research avenues for the future.