Loads for use in the design of ships and offshore structures

Sulphate attack and ettringite formation in the lime and cement stabilized marine clays

Efficiency investigation on energy harvesting from airflows in HVAC system based on galloping of isosceles triangle sectioned bluff bodies

In August 2005, a team surveyed the effects of the December 2004 Indian Ocean tsunami on the southern coast of Oman. Runup and inundation were obtained at 41 sites, extending over a total of 750 km of shoreline. Measured runup ranged from 3.25 m in the vicinity of Salalah to a negligible value at one location on Masirah Island. In general, the largest values were found in the western part of the surveyed area. Significant incidents were documented in the port of Salalah, where a 285-m-long vessel broke its moorings and drifted inside and outside the port, and another ship struck the breakwater while attempting to enter the harbor. The general hazard to Oman from tsunamis may be greatest from the neighboring Makran subduction zone in western Pakistan.

Sri Lanka Field Survey after the December 2004 Indian Ocean Tsunami

Experimental investigation of hydrodynamic force coefficients over AUV hull form

Conventional floating breakwaters are examined and the feasibility of developing a cage floating breakwater is explored. Earlier studies on floating breakwaters reveal that, to achieve a transmission coefficient (\iK\i\dt) less than 0.5, the breakwater width to wave length ratio (\IW/L\N) should necessarily be greater than 0.4 for most of the configurations. Recent studies on cost-effective floating breakwaters indicate that by fixing a row of pipes below the floating body, the \IW/L\N requirement can be reduced to 0.15 without any compromise in the performance. This concept has been adopted in developing a new configuration to serve as: (1) a floating breakwater; and (2) as a possible shallow water cage culture unit. Experiments were conducted to study the performance of the cage floating breakwater under wave and wave-current environment. The results on transmission and reflection coefficients are presented and compared with those reported in the literature. The variation of water surface oscillations and velocities within the cage, the effect of mooring line stiffness, and initial tension on transmission characteristics are also discussed.

Performance of Cage Floating Breakwater

Minimum power requirement is one of the important design criteria for successful operation of underwater vehicles. CFD based prediction and estimation of power requirement is increasingly carried out in practice. However, reliable prediction depends on suitable turbulence models. This paper presents a comparative assessment of four low Reynolds number (low-Re) k- Iµ models for computation of hydrodynamic forces on underwater vehicle hull forms. The low-Re models are being considered more suitable for underwater axisymmetric bodies due to the following merits (i) they have no wall function approximations, (ii) they could compute low turbulence levels such as in the viscous sub-layer and (iii) they could account for the effect of damped turbulence. The low-Re models used in the present study are namely the models of Abe-Kondoh-Nagano (k- Iµ AKN), Chang-Hsieh-Chen (k- Iµ CHC), Launder-Sharma (k- Iµ LS), and Yang-Shih (k- Iµ YS). It has been found that the k- Iµ AKN low-Re model consistently provided superior performance in predicting the flow characteristics around underwater vehicle hull forms. Keywords: Axisymmetric bodies, autonomous underwater vehicle, CFD, damping functions, low Reynolds k- Iµ models, QUICK scheme doi: 10.3329/jname.v2i1.2029 Journal of Naval Architecture and Marine Engineering 2(1)(2005) 41-54

/pdf/application-of-low-re-turbulence-models-for-flow-simulations-35alhu8mhv.pdf

Application of low-Re turbulence models for flow simulations past underwater vehicle hull forms

The current system in the Strait of Singapore is fairly complicated and variable because it is under the influence of major currents driven by trade winds as well as the Asian monsoons. In addition to tidal forcing, circulation in the Strait is governed by a strong hydrodynamic pressure gradient which reverses direction semi-annually and coincides with seasonal monsoon changes. In this investigation, we examine the mechanism that controls the circulation in the Strait of Singapore by using a three-dimensional circulation model forced by hydrodynamic pressure gradient, tides and winds. Model results delineate in detail the characteristics of circulation and hydrodynamic structure in the strait. These results compare favourably with the available field measurements and agree, in general, with observations. It is shown that: (1) the low frequency net transport across the strait correlates well with the seasonal hydrodynamic pressure gradient, and (2) the tidal variation across the strait have a sign...

https://bioone.org/journals/journal-of-coastal-research/volume-2005/issue-215/04-0412.1/Circulation-Modelling-in-the-Strait-of-Singapore/10.2112/04-0412.1.pdf

K. Murali

Papers

Experimental investigation of hydrodynamic force coefficients over AUV hull form

Performance of Cage Floating Breakwater

Application of low-Re turbulence models for flow simulations past underwater vehicle hull forms

Circulation Modelling in the Strait of Singapore

Manning’s ‘n’ co-efficient for flexible emergent vegetation in tandem configuration