Previous to this study, research has shown that small air velocities c
an strongly influence the ignition propensity of a cigarette on uphols
tered furniture simulations. However, data were not available to deter
mine if such velocities existed in practice- The two objectives of the
current effort were to determine (1) the typical steady velocities ne
ar the cushion of a warm chair due strictly to free convection and (2)
the typical unsteady velocities near the crevice of a warm chair due
to a combination of free convection and forced convection as a result
of a person vacating the chair. Typical steady velocities were 40 mm/s
. Typical velocities in the unsteady conditions were 15 mm/s. For the
unsteady conditions large velocities remained long after the chair coo
led to room temperature due to large vortices in the flow with long ti
me constants.