Numerical study on characteristics of buoyant fire-induced smoke movement in a high-rise building stairwell using FDS

Numerical simulations of fire-induced smoke movement in the stairwell of a high-rise building are conducted using FDS, version 6.0.1, with default settings. Twelve scenarios are considered. The required fineness of the grid is determined first by considering the resolution for both the fire source and the vent flow. The grid sensitivity is conducted on the basis of velocity profile at the bottom opening and the vertical distribution of temperature in the stairwell. Previous findings on the required number of cells for vent flows are confirmed. Subsequently the results, including the vertical distribution of temperature, pressure distribution, and neutral plane height in the stairwell, are compared to experimental data.. Good agreement is achieved for the vertical temperature inside the stairwell (maximum relative deviation 12.3%). The influence of the staircase on the pressure distribution is demonstrated by comparing two cases with and without staircase. The difference between the pressure inside the stairwell and the pressure outside increases with height, according to the stack effect. However, the pressure difference evolution is not monotonic when there are staircases inside the stairwell. The neutral plane height value is obtained by post-processing the simulation results. Its position is too high in the simulations, compared to experimental data and the corresponding analytical expression