Extreme fire behaviour
Domingos Xavier Viegas, Emeritus Professor at the University of Coimbra, Portugal |
Short biography: Domingos Xavier Viegas is Professor Emeritus at the University of Coimbra, Portugal, and a member of the Lisbon Academy of Sciences. Within the ADAI (UC), he coordinates the Forest Fire Research Centre (CEIF). Since 1985, he has been dedicated to research on forest fires, with the support of a multidisciplinary team, focusing on topics related to integrated fire management, with particular emphasis on the study of fire behavior and personal safety. He founded the Forest Fire Research Laboratory (LEIF) and has participated in over 100 European and National projects. He is the author or co-author of 130 international papers and has supervised more than 20 doctoral dissertations. He has led his team in the preparation of various reports, commissioned by the Portuguese government and other countries, on major fires and personal accidents.
He promoted the International Conference on Forest Fire Research and chaired its ten editions.
He was awarded the Fire Safety and the Ember Award, by the IAWF in 2017 and in 2022.
Short Summary: The concept of extreme wildfire event (EWE) and the associated processes of extreme fire behaviour are reviewed. The concepts associated to dynamic fire behaviour, based on the role of the interaction between the fire induced convection and the fire spread, are presented and illustrated with some canonic cases. These cases are (i) a point ignition fire in a slope; (ii) a point ignition fire in a symmetrical canyon; and (iii) a junction fire derived from two linear ignitions on a slope. A conceptual model to explain the interaction between the fire and the surrounding flow is proposed, to explain the oscillatory behaviour of the rate of spread of a head fire. The analysis of the amplitude and frequency of the ROS variations is presented to support the inherent uncertainties in fire behaviour prediction. A mathematical model based on the feedback between the fire and the surrounding flow is proposed to predict the positive and negative accelerations that are observed in fire spread. The role of atmospheric stability on fire spread is analysed and illustrated with some preliminary results obtained in the Thermal Tunnel of the University of Coimbra Fire Laboratory, of the average rate of spread of a fire under various vertical temperature gradients.