Interaction Between A Tethered Sphere
And A Free Surface Flow
Author(s)
M. Greco, S. Malavasi & D. Mirauda
Abstract
This paper analyses the vibrations and the flow field around a tethered sphere in
a free surface flow in order to study the influence of the vortex shedding process
on the dynamic response of the obstacle and on its oscillation frequency. The
system is characterized by a low value of the mass ratio (ratio between the mass
of the system and the added mass), a low value of damping and a low value of
relative submergence (ratio between the depth of the current and the diameter of
the sphere). The experiments are set up to measure the movements of the sphere
in the main and transversal directions of the fluid flow with laser sensors and
image analysis, whereas the description of the main wake structures of the flow
downstream of the sphere are provided using the PIV technique.
Keywords: dynamic response, sphere, flow field, vortex structures, resonance
phenomenon.
1 Introduction
Studies on the analysis of the two-dimensional and three-dimensional vibrating
structures in bounded and free surface flows, have highlighted the existence of a
strong dependence of the maximum transverse amplitude on some dimensionless
groups, as shown below:
( ) G S U A A *; * *
max = (1)
where A*max=y0/D is the ratio between the maximum transverse amplitude (y0)
and the characteristic dimension of the body (D), U*=U0/fnD, called reduced
velocity, is the ratio between the mean velocity of the flow (U0) and the product
Keywords
dynamic response, sphere, flow field, vortex structures, resonance
phenomenon.
Related Book
Other papers in this volume
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