Theodore Y. Wu and Chin-Hua Wu Lecture
How to Improve the Performance of an Airtanker Drop
Thursday, February 26, 2026, 4:00 pm
Jim and Sandy Hall Auditorium, 135 Gates-Thomas
Reception to follow in Gates-Thomas Lobby
Professor Dominique Legendre
Wu Visiting Scholar;
Professor of Fluid Mechanics at Toulouse INP,
National Polytechnic Institute of Toulouse
Abstract: Airtanker firefighting is a fascinating tool used to fight wildland fires. Airtankers are, however, developed based on empirical methods, and their performance is only discovered after drop tests made above a grid of cups distributed on a flat field with no vegetation (the cup & grid method), developed during the 1990s. Dropping a liquid from an aircraft seems easy to achieve because the released liquid directly falls to the ground due to gravity. However, the fluid dynamics processes that govern this practice are characterized by rich and varied physical phenomena, and controlling the resulting fluid distribution of the drop pattern raises many scientific issues.
The liquid column penetration in the air, its large-scale fragmentation, and an intense surface atomization give shape to the rainfall produced by the airtanker and the final product deposition onto the canopy. The respective roles of these mechanisms are described and analyzed here in order to determine the parameters of importance for improving airtanker drop performance for more efficient firefighting.
Bio: Prof. Dominique Legendre graduated with a PhD in Fluid Mechanics from Toulouse INP, France, in 1996. He has been a Professor of Fluid Mechanics at Toulouse INP since 2007, and he is Deputy Director of IMFT (Institut de Mécanique des Fluides de Toulouse), one of the leading fluid mechanics institutes in Europe. He has been Chairman of the Governing Board of the International Conference on Multiphase Flows (ICMF) from 2022 to 2025.
His main line of research is multiphase flows, in particular bubble and drop dynamics, including heat and mass transfer, icing, and wetting phenomena. Over the last decade, he has developed an original research program on airtanker firefighting efficiency with a strong connection to the aerial firefighting industry. In particular, he has developed the NaSCa code to model ground deposits of liquid dropped by any aerial system. In 2019, a patent was granted for a new delivery system, KIOS, in collaboration with Kepplair Evolution, and he is now an expert for the KE72 project to transform an ATR72 into an airtanker. He has led several international publications on the subject, in particular a contribution to the Annual Review of Fluid Mechanics in 2024. In 2023, in Washington, DC, he delivered an invited keynote lecture on the fluid mechanics of airtanker firefighting at one of the most prestigious international fluid mechanics conferences (the Annual Meeting of the Division of Fluid Dynamics of the American Physical Society). For all his contributions, he received the "Transfert Technologique" Award of Toulouse University in 2022.
About the Lecture
The Theodore Y. Wu and Chin-Hua Wu Lecture was established to honor the enduring legacy of two extraordinary individuals who shaped not only the Caltech community, but also the lives of countless students and scholars from around the world: Professor Theodore Y. Wu and his wife, Dr. Chin-Hua Wu. Twenty twenty-four marked what would have been Professor Wu's 100th birthday and in celebration of his monumental contributions to science and education, the endowed Dr. Theodore Y. Wu and Dr. Chin-Hua Wu Visiting Professorship Fund was established. This initiative is designed to bring distinguished scholars to the Institute to teach, collaborate, and inspire our faculty and students.
The Lecture is held annually and is made possible through the generosity of family, friends and colleagues who have contributed to the Dr.Theodore Y. Wu and Dr. Chin-Hua Wu Visiting Professorship Fund. To make a gift or learn more, please make a gift online or contact Laura J. Grinnell, Senior Director of Development, via email [email protected] or by phone at 626-395-2385.