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Development and Evaluation of Two New Droplet Evaporation Schemes for Fire Dynamics Simulations



Randall J. McDermott, Jason Floyd


The evaporation of sprinkler droplets is an important phenomena in fire simulations both for heat removal from the gas and for heat removal from surfaces. In this paper, we address the problems of potential numerical instability and super-saturation that may occur in explicit time integration of the droplet equations. Two novel numerical approaches are developed and evaluated. The first is based on an analytical solution that relaxes the cell composition and temperature toward the equilibrium values. The second method is an implicit solution to the droplet equations. The two approaches are implemented in the Fire Dynamics Simulator (FDS) and verified and validated using both single droplet and practical sprinkler calculations. Ultimately, the implicit approach is demed the most cost effective for practical fire simulations.
Conference Dates
June 12-16, 2017
Conference Location
Lund, SE
Conference Title
International Symposium on Fire Safety Science


FDS, droplet evaporation, sprinklers, watermist


McDermott, R. and Floyd, J. (2017), Development and Evaluation of Two New Droplet Evaporation Schemes for Fire Dynamics Simulations, International Symposium on Fire Safety Science, Lund, SE, [online],, (Accessed March 4, 2024)
Created May 15, 2017, Updated April 6, 2022