Title: Second law analysis of wildfire evolution under wind and slope effect

Authors: Elisa Guelpa; Vittorio Verda

Addresses: Energy Department, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129, Turin, Italy ' Energy Department, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129, Turin, Italy

Abstract: This paper aims at investigating possible relations between the main driving forces in forest fires and the corresponding entropy generation. Second law analysis is applied to an uncontrolled fire event in a grassy area. The system is first studied through a full physical numerical model, with the aim of collecting local data in the same way as through pervasive sensors. Three terms contributing to the entropy generation are analysed: mass transfer, heat transfer and transient term. Results show that the first term is globally large, especially when large wind velocities and terrain slopes are considered. The second term is also large and becomes dominant in the case of lower driving forces. The third term, instead, gives an almost negligible contribution. In addition, the total entropy generated increases with increasing slope or wind speed, and can be approximated by a logarithmic evolution with a mean error of about 5%.

Keywords: second law analysis; forest fire; wildfire modelling; entropy generation; WFDS; Wildland Fire Dynamic Simulator.

DOI: 10.1504/IJEX.2018.092508

International Journal of Exergy, 2018 Vol.26 No.1/2, pp.93 - 106

Received: 22 Aug 2017
Accepted: 17 Nov 2017
Published online: 23 Jun 2018 *

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