Drag coefficients of the downstream cylinder in a tandem arrangement
of two models aligned with the flow are shown in this
work. The models, which experienced vortex-induced vibrations
with wake interference, had an external diameter of 16 mm and
a total length of 1.5 m giving an aspect ratio of about 94. More
than 400 runs were carried out in a water flume with only the
lower 40% of the models exposed to the current. The flow speed
was varied up to 0.75 m/s giving Reynolds numbers in the range
from 1200 to 12000. A supporting structure. where the models
were attached. allowed changes in the centre to centre distances
and in the applied top tensions. Separations of up to 4 diameters
were tested with tension variations from 15 to l10 N. Reduced
velocities based on the fundamental natural frequency reached
values up to 16. The mass ratio of the models was around 1.8
and the combined mass-damping parameter about 0.05
