FLOW AROUND A CYLINDER - istiarto

Vorticity fields in the scour hole
– 5.36 –
As in the flat-bed case, the vorticity fields were computed from the radial and vertical
velocity components and are presented in Fig. 5.19. Shown in this figure are the vorticity
contours obtained from the simulation and the measurement. While the vorticity was
computed using all data points, shown here are the contours in the region of important
vorticity, r ≤ 60 [cm] and z ≤ 5 [cm]. The following is to be remarked:
Fig. 5.19 Computed and measured vorticity fields, � � , in the planes � = 0°, 90°, 180°.
The shaded area indicates regions of negative vorticity fields.
Flow around a cylinder in a scoured channel bed.
� In the plane � = 0° (Fig. 5.19a,b), a qualitative agreement on the general patterns of
the vorticity field in the scour hole is achieved, being the characterized by a strong
positive vorticities in the upstream inclined bed and a negative ones at about
r = 30 [cm]. Quantitatively, though, the computed vorticity everywhere is weaker