FLOW AROUND A CYLINDER - istiarto

– 2.48 –
maximum downward flow is w ≈ –0.13 [m/s] (0.29U∞) which is much weaker (about
50%) than that in the plane � = 0° and is slightly weaker (80%) than that in the plane
� = 90°.
Turbulence intensities in the plane � = 135°. The three components of the turbulence
show an increasing intensity compared to those of the previous planes, � = 0°, 45° and
90°. The turbulence intensifies closer to the cylinder, notably at the lower layer. At the
upper layer, it is more or less constant. The three components, the u �� u ��,
v �� v ��,
and
w ��w
��,
are well organized and their profiles have a similar shape. The u �� u �� and the
w ��w
�� components are the most and the least dominant, respectively, with an exception
close to the bed where the v �� v �� is comparable to the u �� u ��.
The u �� u ��,
notably at the
lower layer, increases from the maximum value of u �� u �� ≈ 0.065 [m/s] at r = 70 [cm] to
u �� u �� ≈ 0.12 [m/s] at r = 10 [cm]. The v �� v �� behaves like the u �� u ��.
It is lower than the
u �� u ��,
but close to the bed, the two components become comparable. The w ��w
�� is
always the least important. Approaching the cylinder, it only slightly increases; the
maximum w ��w
�� increases from 0.04 to 0.06 [m/s].
Reynolds stresses in the plane � = 135°. The Reynolds stresses in this plane continue to
increase compared with those in the previous planes; they are about 2.8 times higher than
those in the plane � = 0°. The Reynolds stresses, both at the upper layer and lower layer,
increase as they are approaching the cylinder. The �u �� w �� is always positive, whereas the
�v �� w �� has positive and negative values. The �u �� w �� has a peak at the lower layer whose
magnitude increases from �u �� w �� = 0.001 [m2 /s2 ] at r = 70 [cm] to �u �� w �� = 0.005 [m2 /s2 ]
at r = 22 [cm]. As it further approaches the cylinder, the peak slightly diminishes to
�u �� w �� ≈ 0.004 [m2 /s2 ] at r = 10 [cm]. The �v �� w �� has a negative value at the upper layer,
a positive value at the lower layer, and tends to a negative value close to the bed. The
magnitude increases as it approaches the cylinder. At the two profiles closest to the
cylinder, at r = 12 and 10 [cm], the �v �� w �� has an alternating positive-negative value.