Local peak pressure and conical vortex on building

Characteristics and cause of local peak suction are discussed through a relation with the conical vortex. The peak suction is induced by the large and strong conical vortex formed on the roof and the wall when the gust attacks a building instantly from a particular direction in any mean wind directions. The large-scale gust is responsible for the formation of the vortex and the occurrence of the peak suction, because the development of the strong vortex takes time at least when the fluid particle travels a distance 4–5 times the roof size. The modification of the edge is very effective to reduce the peak suction, as it controls effectively the separation of the shear layer. When the eaves of the flat roof are recessed by 110 of the height of the building, the peak suction can be reduced to 23 of that on the roof without the recession.