AbstractFire whirls are often reported to appear in large-scale urban and forest fires and cause significant damage, injuries and fatalities, due to winds that are similar to tornadoes and intense radiant heat. In particular, disastrous urban fires that result from huge earthquakes can easily induce large fire whirls. This paper presents a CFD simulation on fire whirls in urban fires, and the effect of fire-fighting actions on the suppression (control or extinguishment) of fire whirls is addressed. Assuming that aerial fire-fighting activities are successfully conducted in part of the fire area, it is found that the shear wind caused by the fire may disappear and then fire whirls will terminate naturally. At the same time, the effect of partial fire extinction on the strength of fire whirl is discussed in detail. It is found that if some areas along the wind flow are extinguished, the fire whirls can be terminated. Also the fire extinguishment can reduce the strength of fire whirls, even if they are difficult to terminate.