330
K. B. Rajasekarababu and G. Vinayagamurthy
the setback building were seen reduced by 5% and 12%, respectively at y/H = 0.475.
At the same instance, there is a dramatic reduction of 51% in the leeward face for
setback and just 16% for taper. Left side face of the taper and setback was observed
to be reduced by 12% and 32%, respectively. The wind profile exponentially showed
changing along with height; the increase of wind velocity influences the wind flow
around the building. The pressure coefficients on the edges of the rect building at
y/H = 0.725 observed a considerable drop as shown in Fig. 3c. Shows that a huge
suction is created on the side faces. Similarly, a large fluctuation was noticed in the
leeward face, which indicates the vortex formation. Furthermore, at y/H = 0.725 on
the right side face of the taper and setback building, Cp decreased by 70% and 90%,
respectively. Moreover, there is also a 54% and 82% reduction of Cp on the left side
faces of the taper and setback buildings, respectively. At y/H = 0.975, taper and rect
buildings evidenced vortex shedding and wake formation in downstream as a result,
the pressure drops on leeward face as shown in Fig. 3d.
3.2 Instantaneous Vortex Structure Formation Around
Buildings
The vortex formations on buildings are visualized in CFD to compare the vortex
structures behind them; a Q-criterion was used to identify the wake vortices using
Eq. 2.
Q =
1
2
r i j r i j − s i j s i j
Isosurface Q-criterion with non-dimensional velocity contour is used in this study
to obtain the preferred large eddy flow structure (excluding small-scale vortices of
no interest). The instantaneous vortex structures identified by Q = 750 behind the
building with IDDES turbulence model using fine mesh are shown in Fig. 4. It
represents the capability of the simulation to solve turbulence by providing shielding
function for the SST-based IDDES model to achieve highly chaotic large and small
scale vortices. The IDDES captures the massively separated flow of 3D streamwise
Fig. 4 Instantaneous vortex structure around buildings (Isosurface of velocity (Q = 750 ms −1 ))
a Rectangle, b Taper and c Setback
K. B. Rajasekarababu and G. Vinayagamurthy
the setback building were seen reduced by 5% and 12%, respectively at y/H = 0.475.
At the same instance, there is a dramatic reduction of 51% in the leeward face for
setback and just 16% for taper. Left side face of the taper and setback was observed
to be reduced by 12% and 32%, respectively. The wind profile exponentially showed
changing along with height; the increase of wind velocity influences the wind flow
around the building. The pressure coefficients on the edges of the rect building at
y/H = 0.725 observed a considerable drop as shown in Fig. 3c. Shows that a huge
suction is created on the side faces. Similarly, a large fluctuation was noticed in the
leeward face, which indicates the vortex formation. Furthermore, at y/H = 0.725 on
the right side face of the taper and setback building, Cp decreased by 70% and 90%,
respectively. Moreover, there is also a 54% and 82% reduction of Cp on the left side
faces of the taper and setback buildings, respectively. At y/H = 0.975, taper and rect
buildings evidenced vortex shedding and wake formation in downstream as a result,
the pressure drops on leeward face as shown in Fig. 3d.
3.2 Instantaneous Vortex Structure Formation Around
Buildings
The vortex formations on buildings are visualized in CFD to compare the vortex
structures behind them; a Q-criterion was used to identify the wake vortices using
Eq. 2.
Q =
1
2
r i j r i j − s i j s i j
Isosurface Q-criterion with non-dimensional velocity contour is used in this study
to obtain the preferred large eddy flow structure (excluding small-scale vortices of
no interest). The instantaneous vortex structures identified by Q = 750 behind the
building with IDDES turbulence model using fine mesh are shown in Fig. 4. It
represents the capability of the simulation to solve turbulence by providing shielding
function for the SST-based IDDES model to achieve highly chaotic large and small
scale vortices. The IDDES captures the massively separated flow of 3D streamwise
Fig. 4 Instantaneous vortex structure around buildings (Isosurface of velocity (Q = 750 ms −1 ))
a Rectangle, b Taper and c Setback