Flow structure around a 3-D rectangular prism in a turbulent boundary layer

Flow around a three-dimensional (3-D) rectangular prism has been investigated by using a particle image velocimetry technique. The prism was immersed in a thick turbulent boundary layer. The ratio of the boundary layer thickness and the model height was about 0.06. Measurements were made at Reynolds number of 7.9×103 which is based on free stream velocity and model height. Detailed flow structures and characteristics including three circulation zones were obtained by averaging over a large number of instantaneous velocity maps. The 3-D structure in a wake zone is clearly seen from mean flow streamline topology. Turbulent kinetic energy distribution is also obtained approximately. Maximum turbulent kinetic energy was found at the separated layer in the upper boundary of the separation bubble near the leading edge of a roof. The magnitude of the maximum energy is about 2.5 times that in the wake region.