FLOW AROUND A CYLINDER - istiarto

– 5.19 –
Fig. 5.9 Definition sketch of the coordinate system and the vorticity, ��.
5.5.3 Results of the simulation and comparison to the experimental data
The evaluation of the results of the numerical simulation (see Chapter 4) is made for the
velocity fields and the water surface. Herewith they are compared to the experimental
data (see Chapter 2). Detailed comparison of the 3D velocity profiles in the planes where
the experimental data are available is first presented (Fig. 5.10). The velocity fields,
resulted from the simulation and the measurement, are then presented by vector plots
(Fig. 5.11) and contour plots (Fig. 5.12) in three selected planes, � = 0°, 90°, and 180°, to
show the general pattern of the flow. Next, the prediction of the flow pattern at the
bottom corner of the cylinder is highlighted by contour plots of the computed and the
measured vorticity fields (Fig. 5.13), obtainable from the corresponding 2D velocity
components in those three planes. Finally, an evaluation is made on the computed water
surface profile along the longitudinal section of the symmetry plane and along the
cylinder circumference (Fig. 5.14).�
Vertical distribution of the 3D velocity components
The comparison between the computed and the measured vertical distributions of the 3D
velocity components are done for some selected profiles. Shown in Fig. 5.10 are 20
distributions of the 3D velocity components, u(z), v(z), and w(z), in the planes where
measurements data are available, � = 0°, 45°, 90°, 157.5°, and 180°. Four stations at
r D p � 1.5, 1, 0.75, and 0.55, being considered representative ones, are selected from
each plane. It can be seen from the comparison in Fig. 5.10 that the computed velocity
distributions are in a good agreement with the measured ones, notably in the upstream
region, � = 0°, 45°, and 90°. The agreement, however, is less evident in the wake region,