Abstract
The turbulent characteristics of flow separation induced by a trapezoidal and two rectangular prisms immersed in a uniform flow were studied experimentally using particle image velocimetry. The streamwise aspect ratios (AR) of the two rectangular prisms were 3 and 4. The streamwise AR of the trapezoidal prism was based on its upper length and was 3. The Reynolds number based on the freestream velocity and the prism height was 14700. The flow topology of symmetrical wake flows over and behind the rectangular prisms and asymmetrical wake flow over and behind the trapezoidal prism were analyzed using the mean flow and Reynolds stresses. The results indicate that the mean flow reattaches onto the rectangular prisms but does not reattach onto the trapezoidal prism. Dual local regions of elevated streamwise Reynolds normal stress occur in the wake region irrespective of AR and the body geometry. However, the dual elevated regions are only symmetric about the horizontal centerline of two rectangular prisms. Probability density function (PDF), two-point correlations and proper orthogonal decomposition (POD) analyses were employed to investigate the dynamics of the coherent structures formed over and behind the prisms.
