Prediction of smoke movement in atria: Part I Physical concepts.

In recent years, the atrium building has become commonplace. This paper explains the physical concepts of the steady fire, unsteady fire, zone fire model, and the fire plume that are the basis of atrium smoke management. The approach to smoke control design calculation in codes is based on the zone fire model concept. In the zone model, smoke forms an upward-flowing fire plume that reaches the ceiling and is considered to form a perfectly mixed layer under the ceiling of the room of fire origin. This paper shows that the commonly used virtual origin correction to the plume equations is not needed for atria smoke management. For the purposes of smoke management, the deviations of fire plume mass flow due to omitting the virtual origin correction can be neglected.