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A Simple Reaction Time Scale for Under-Resolved Fire Dynamics



Randall J. McDermott, Kevin B. McGrattan, Jason E. Floyd


A reaction time scale model is developed for use in the eddy dissipation concept (fast chemistry limit) closure of the mean chemical source term in large-eddy simulation of fires. The novel aspect of the model is to consider a scaling regime for coarse mesh resolution based on buoyant acceleration. The model computes local time scales for diffusion, turbulent advection, and buoyant acceleration and takes the minimum of these as the local mixing time. The new model is implemented in the Fire Dynamics Simulator (FDS) and tested by comparing flame height predictions against the correlation of Heskestad.
Proceedings Title
Tenth International Symposium on Fire Safety Science
Conference Dates
June 20-24, 2011
Conference Location
College Park, MD


ire modeling, large-eddy simulation, eddy dissipation concept, flame height


McDermott, R. , McGrattan, K. and Floyd, J. (2011), A Simple Reaction Time Scale for Under-Resolved Fire Dynamics, Tenth International Symposium on Fire Safety Science, College Park, MD, [online], (Accessed June 19, 2024)


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Created June 20, 2011, Updated February 19, 2017