Vortical structures around a surface-mounted pyramid in a thin boundary layer

Modeling MAV Response in Gusty Urban Environment

“…More recently, the wind tunnel experiments focused on investigating flows around more exotic building shapes. For example, AbuOmar and Martinuzzi [14] examined vortical structures around sharp-edge pyramids that produced an "owl-face of the second kind" flow pattern.…”

Flow structure in the wake of a low-aspect-ratio wall-mounted bluff body

“…These bifurcation lines were formed by three alternating-sign mean vortices along the surface. Further PIV studies by Martinuzzi (2008) and AbuOmar and Martinuzzi (2008) showed that these vortex Hence, whereas high-aspect-ratio cylinders have been shown to produce base vortices under certain conditions and moderate-aspect-ratio cylinders generally do not, a new trend appears to emerge in the behavior of streamwise vorticity when the aspect ratio is near one (which we will refer to as low-aspect-ratio). The above discussion demonstrates that the wake structure and dynamics of these low-aspectratio obstacles can be highly varied as are the geometries that produce them.…”

“…While most investigations of the flow structure generated by wall-mounted obstacles have focused on circular cylinders and prisms, as suggested by the collection of literature described above, other geometries have been investigated. These include hemispheres and spheres (Okamoto, 1980;Toy, 1986, 1988;Shamloo et al, 2001;Tsutsui, 2008;Papanicolaou et al, 2011;Ozgoren et al, 2012;Papanicolaou et al, 2012a), tapered plates, pyramids and cones (Vosper et al, 1999;Castro et al, 2001;Martinuzzi and AbuOmar, 2003;AbuOmar and Martinuzzi, 2008;Martinuzzi, 2008), and modified cylinders and prisms Toy, 1986, 1988;Leder, 2003;Sousa and Pereira, 2004). A few studies have also investigated on flow structure around an axisymmetric hill (Simpson et al, 2002;Byun and Simpson, 2006;Krajnović, 2008).…”

“…More complex shedding behaviors may be observed in the wakes of noncylindrical obstacles. For example, cellular shedding has been observed in cones (Papangelou, 1992;Vosper et al, 1999;Vosper, 2000;Castro et al, 2001), tapered plates (Castro and Rogers, 2002;Castro and Watson, 2004), and pyramids (Mart-inuzzi and AbuOmar, 2003;AbuOmar and Martinuzzi, 2008;Martinuzzi, 2008) in which either the shedding frequency or Strouhal number was found to be constant within each cell. The location and size of the cells are functions of the degree of taper, the aspect ratio, and the end conditions.…”

“…While no vortex shedding was observed for TR = 0.36, weak Kármán-like shedding at St = 0.18 was observed for TR = 0.58 and 1, in relatively thick boundary layers (δ/H = 1.1 and 0.68, respectively) despite the extreme taper and the spatial extent of the approaching shear flow. Notably, no coherent shedding was observed for a plate of TR = 0.58 with the size doubled, emphasizing the importance of boundary layer thickness, though still not well-understood.Further insight into the shedding behavior and wake topologies of tapered structures was introduced by Martinuzzi and AbuOmar in their investigations of pyramid-shaped obstacles in thin boundary layers and shedding behavior was classified based on apex angle ζ (Martinuzzi and AbuOmar, 2003;AbuOmar and Martinuzzi, 2008;Martinuzzi, 2008)…”