Presence of the outer perforated cylinder reduces the direct wave impact on the inner cylinder, which has been testified by many researchers. However, the force reduction mechanism, which is complicated due to the wave-porous structure interaction, needs to be addressed in detail. The present study explains the mechanism with the aid of the computational fluid dynamics (CFD) tool STAR CCM+. This package is chosen for its capabilities to simulate viscous and turbulence effects caused by passage of waves. For the present study, flow fields around the twin cylinders with different orientations are examined with and without the outer perforated cover. Mechanism contributing to the reduction of force on the existing structure is explained in physical terms, and force reduction is quantified. The present study has direct application in the retrofitting application of offshore members. © 2016, Chinese Ocean Engineering Society and Springer-Verlag Berlin Heidelberg.

Srinivasan Chandrasekaran

Department of Ocean Engineering

N. Madhavi

Computational fluid dynamics

Flow fields

FLUID DYNAMICS

OFFSHORE STRUCTURES

DIRECT WAVES

Existing structure

FORCE REDUCTIONS

Hydrodynamic forces

INNER CYLINDER

Porous structures

TURBULENCE EFFECT

WATER PARTICLE KINEMATICS

Cylinders (shapes)

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

China Ocean Engineering

The direct impact caused by the waves can be efficiently reduced by encompassing the existing member with a perforated cover to reduce wave forces on the damaged members. Mathematical models showing the variation of the water particle kinematics on the cylindrical members, encompassed with perforated cover, is scarce in the literature; few experimental investigations are only available. Numerical investigations of the scaled model of a cylindrical member, encompassed with an outer perforated cover in the splash zone, are examined and the variations of the water particle kinematics along the depth of cylinder are obtained for perforation ratio ranging between 10% and 15% using computation fluid dynamics software. Design charts are developed for different sea states in the deep-water conditions, which aids the design engineers to evaluate the force on the structural members encompassed by perforated covers without carrying out any rigorous numerical analyses. © 2014, Taylor &amp; Francis.

Ships and Offshore Structures

Design aids for offshore structures with perforated members

Perforated piles are used in near-shore breakwaters for coastal protection and deep water platforms for oil exploration. Emerged and submerged perforated cylindrical structures reduce wave-structure interactions and scouring problems considerably, but their use on a floating structure is limited. Mathematical model is developed to introduce perforated walls in floating structures and method of solution is discussed. Eigenfunction expansion approach is used to derive velocity potentials based on which hydrodynamic forces on perforated cylinders are obtained. An example tension leg platform having perforated caissons is chosen; length of the perforated region and its location on tension leg platform are varied to determine their influence on its motion. For increase in perforation length, fluid-structure interaction reduces, causing decrease in surge and pitch responses. However, increase in perforated length in the lower part of column does not significantly increase these responses; heave remains relatively unaffected regardless of the length of perforation in the columns. © 2010 Taylor &amp; Francis.

Potential-flow-based numerical study for the response of floating offshore structures with perforated columns

The International Journal of Ocean and Climate Systems

Hydrodynamic Response of Tension Leg Platforms with Perforated Members

Ocean Engineering

Short-crested waves interaction with a concentric cylindrical structure with double-layered perforated walls

Fuel Cells Bulletin

CD adapco simulation tool for SOFC design

Variation of flow field around twin cylinders with and without the outer perforated cylinder — Numerical study

Journal	Data powered by TypesetChina Ocean Engineering
Publisher	Data powered by TypesetSpringer Verlag
ISSN	08905487
Open Access	No