Structures and marine facilities play a crucial role in economic development and
international communications. These installations include ports, bridges, tunnels,
pipelines, and offshore oil and gas platforms, contributing significantly to maritime
transportation and energy resource extraction. Many of these structures are
submerged in water, subject to hydrodynamic forces due to marine currents.
Therefore, investigating fluid-structure interaction is crucial in designing these
structures. Additionally, when multiple structures are positioned together in the sea,
it can impact the flow patterns and forces acting on the structures.
This study focuses on the effect of an important phenomenon in fluid-structure
interaction called vortex-induced vibration, examining its impact on two cylinders
near the free surface. The simulation utilizes ANSYS Fluent software, employing
the Eulerian-Eulerian approach and fluid volume method to track the free surface.
The study is conducted in two dimensions, considering irregularities and for a
laminar flow regime. To validate the study, four different scenarios are examined
for stationary and vibrating cylinders in single-phase and two-phase flows, yielding
good agreement with existing literature. The effects of reduced velocity, Froude
number, and cylinder spacing on hydrodynamic characteristics and vibration
response are investigated.
Results indicate that with increasing reduced velocity, the average in-line and
transverse displacement of the front and rear cylinders increases. The displacement
range of the rear cylinder, along with its hydrodynamic coefficients, are higher that
of the front cylinder. Increasing the Froude number leads to the instability of the
free surface, the formation of vortices, and even the suppression of vortex shedding
from the cylinder. At Froude number 0.3, as the cylinder spacing increases,
instability in the free surface and the vortices formed behind the second cylinder
become more pronounced. Furth