Description
Recent studies have identified conditions under which smoke flow in tunnel fires splits in two, leaving a low temperature and comparatively smoke free zone in the middle of the tunnel, downstream of the fire. This is the ‘bifurcation flow’ zone. The literature is summarised and new numerical simulations of bifurcations are presented. It is shown that the bifurcation phenomenon is not due to the tunnel, but can exist in the open air. However, tunnel conditions do affect the subsequent flows, and how they recombine. No positive effect of the phenomenon is identified that could be exploited in tunnel ventilation design.
