Time-averaged LDA measurements and time-resolved numerical flow
predictions
were performed to investigate the laminar flow induced by the harmonic
in-line
oscillation of a circular cylinder in water at rest. The key parameters,
Reynolds number
Re and Keulegan–Carpenter number KC, were
varied to study three parameter
combinations in detail. Good agreement was observed for Re=100
and KC=5
between measurements and predictions comparing phase-averaged velocity
vectors.
For Re=200 and KC=10 weakly stable and non-periodic flow
patterns occurred,
which made repeatable time-averaged measurements impossible. Nevertheless,
the
experimentally visualized vortex dynamics was reproduced by the two-dimensional
computations. For the third combination, Re=210 and KC=6,
which refers to
a totally different flow regime, the computations again resulted in the
correct fluid
behaviour. Applying the widely used model of Morison et al. (1950)
to the computed
in-line force history, the drag and the added-mass coefficients were calculated
and
compared for different grid levels and time steps. Using these to reproduce
the force
functions revealed deviations from those originally computed as already
noted in
previous studies. They were found to be much higher than the deviations
for the
coarsest computational grid or the largest time step. The comparison of
several
in-line force coefficients with results obtained experimentally by
Kühtz (1996) for β=35
confirmed that force predictions could also be reliably obtained by the
computations.
Flow-Induced Vibration of Bluff Bodies. Vortex-Induced Vibration of a Cantilever Circular Cylinder in Super-Critical Reynolds Number Flow and Its Suppression by Structure Damping.
