Studies on Caisson Type Breakwater – A Physical and Numerical Approach
Date
2023
Authors
V., Kumaran
Journal Title
Journal ISSN
Volume Title
Publisher
National Institute Of Technology Karnataka Surathkal
Abstract
The design and construction of coastal structures such as breakwaters, at greater water
depths is rapidly increasing as a result of the increasing draught of large vessels and
off-shore land reclamations. Vertical caisson-type breakwaters may be the best
alternative compared to ordinary rubble mound breakwaters in larger water depths, in
terms of performance, total costs, environmental aspects, construction time and
maintenance. To fulfil the functional utility and impact of the structure on the sea
environment, it is necessary to study the hydraulic performance of such breakwaters.
In the present project, the hydrodynamic performance of caisson breakwater with
various geometric configurations are studied in detail. In the first phase, a physical
model approach is carried out extensively to study the stability of toe protection for
vertical caisson breakwater. The determination of the size of the toe armour units and
their cross-section for the stable design are investigated. The applicability of the
Brebner and Donnelly (Coast Eng Proc 1: 24, 1962) design curve for depth-limited
conditions is validated for a certain fixed relative foundation depth (d1/d). In the second
phase, an investigation of the non-perforated caisson type breakwater is performed
considering different wave conditions. The variation of dynamic wave pressure, wave
force, wave run-up, and wave reflection are determined for this structure. The
maximum wave force on the caisson breakwater is calculated from measured pressure
values and is compared with the wave forces calculated by Goda’s and Sainflou wave
theories. The comparison of results illustrate that the Goda’s formula provides a good
estimation of wave force distribution compared with the experimental findings. In the
third phase, a numerical model of caisson breakwater is developed to study its
performance using the computational fluid dynamics (CFD) approach using Ansys-
Fluent and validated the same using experimental data. In the fourth phase, the
experimental investigations are carried out on non-perforated vertical wall breakwater
with the presence of a vertical and horizontal slotted barrier. In the fifth phase, the
perforations (i.e 8 %, 10%, 13%, 15%, 20%) are introduced in the front face of the
caisson breakwater to analyse the hydraulic performance to arrive at better perforations
in reducing the wave forces, wave reflection and wave runup.
Description
Keywords
Caisson Breakwater, Slotted Barrier, Perforated Caisson, CFD