Numerical prediction of ceiling jet temperature profiles during ceiling heating using empirical velocity profiles and turbulent continuity and energy equations

Transient development of temperature profiles of an unconfined ceiling jet, induced by a constant fire source, are modeled using the Favré-averaged turbulent continuity and energy equations using Prandtl mixing length along with the equation of state. The primary motivation is to examine if one can use existing empirical velocity profiles to obtain temperature profiles, during the transient heating, as well as the vertical component of velocity of the ceiling jet and thus use these transient ceiling jet temperature profiles in room fire models. The numerical predictions show that the approach is promising, however, the agreement with the experimental data (two different heights of 1·0 and 0·5 m) suffers near the ceiling. The numerical results generally under-predict the 1·0 m case and over-predict the 0·5 m case.