ELIGMOS: time domain simulation of the maneuvering of ships in deep and shallow waters

Calm water manoeuvring simulations are commonly used at the initial design stage as they provide useful an practical insight concerning ship's manoeuvrability and compliance with the relevant IMO criteria. In this paper the authors present ELIGMOS; a time-domain numerical code utilizing a 3-DOF manoeuvring model based on the MMG method. For the validation of the code's predictions, a comparison with the experimental results on the turning ability of S-175 has been conducted. The paper presents also the investigation performed regarding the accuracy of certain empirical formulas for the derivation of the manoeuvring derivatives is also investigated, especially for the case of shallow water where experimental data and results remain scarce. The code is written in C++ programming language, adopting a modular approach for the calculation of external forces and moment (i.e. hydrodynamic hull, rudder and propeller) which allows future enhancements with the introduction of additional terms

Sensitivity analysis of the tool for assessing safe manoeuvrability of ships in adverse sea conditions

In 2013, International Maritime Organization (IMO) introduced the Interim Guidelines for determining the minimum propulsion power to maintain the manoeuvrability of ships in adverse conditions. Considering the sufficiency of propulsion system in adverse sea conditions, the European project SHOPERA has developed alternative processes and tools for assessing safe manoeuvrability of ships. The main objective of these procedures is to identify the critical conditions where the vessel maintains its course keeping and manoeuvring ability at the vessel available propulsion power by using basic ship design values as input into the simplified methods proposed. Outcomes of this project were submitted and discussed in the 70th session of IMO’s Marine Environmental Protection Committee. In this paper, a brief description of these new assessment procedures is presented and a sensitivity analysis is conducted. The analysis is performed for a range of different open water propeller and hull resistance characteristics, hull – propeller interaction factors and engine power limit values, investigating the influence of these various performance parameters on the performance of the vessel

The effect of spacing on the vortex-induced vibrations of two tandem flexible cylinders

Vortex-induced vibrations (VIV) of two flexible cylinders arranged in tandem are studied using a two-way fluidstructure interaction (FSI) method with different spacing ratios (Sx/D) at Reynolds number Re = 500 using a twoway fluid-structure interaction (FSI) method. The main objective of this study is to investigate the effect of spacing on the hydrodynamic interactions and the VIV responses of these cylinders. The responses of the two flexible cylinders are found to be similar to the classical VIV responses at small Sx/D. Once Sx/D is large enough for the vortices to become detached from the upstream cylinder, the response of the upstream cylinder is similar to the typical VIV response whereas the downstream cylinder undergoes wake-induced vibration (WIV). The characteristics of the response of the downstream cylinder in the present study are similar to those of the first two response regimes classified by previous researchers. The third regime is not observed for the flexible downstream cylinder with both ends fixed. The two changes in the phase relation between the cross-flow displacements of the two tandem flexible cylinders are discovered to be linked with the initial-upper branch transition and the upperlower branch transition, respectively. The correlation lengths of the two flexible cylinders decrease significantly in the transition range between the upper and lower branches. Three modes of vortex shedding (2S, P + S and 2P) have been identified in the present study. The upper-branch 2P mode is found to be associated with largeamplitude vibration of the upstream cylinder and the P + S mode is observed to be related to large-amplitude vibration of the downstream cylinder for Sx/D = 3.5 and 5. On the other hand, the lower-branch 2P mode leads to small-amplitude vibration of the downstream cylinder in the post-lock-in range at Sx/D = 2.5. The relative phase shifts of the sectional lift coefficients on different spanwise cross sections can be attributed to the variation of the vortex shedding flow along the flexible cylinders, and these phase shifts result in poor phasing between the forces and the displacements which is related to the decrease of the correlation lengths

Functional genome-wide siRNA screen identifies KIAA0586 as mutated in Joubert syndrome

Defective primary ciliogenesis or cilium stability forms the basis of human ciliopathies, including Joubert syndrome (JS), with defective cerebellar vermis development. We performed a high-content genome wide siRNA screen to identify genes regulating ciliogenesis as candidates for JS. We analyzed results with a supervised learning approach, using SYSCILIA gold standard, Cildb3.0, a centriole siRNA screen and the GTex project, identifying 591 likely candidates. Intersection of this data with whole exome results from 145 individuals with unexplained JS identified six families with predominantly compound heterozygous mutations in KIAA0586. A c.428del base deletion in 0.1% of the general population was found in trans with a second mutation in an additional set of 9 of 163 unexplained JS patients. KIAA0586 is an orthologue of chick Talpid3, required for ciliogenesis and sonic hedgehog signaling. Our results uncover a relatively high frequency cause for JS and contribute a list of candidates for future gene discoveries in ciliopathies

An experimental study of hull girder loads on an intact and damaged naval ship

The study reported in this paper is focused on experimental investigation of the hull girder loads on an intact and damaged naval ship DTMB 5415 at zero speed. The experimental campaign was carried out in head and beam regular waves at the University of Strathclyde. The effect of the use of moorings in the model experimental setup was investigated in the context of loads assessment, and the moorings are shown to influence the measured hull girder loads at some wave frequencies compared to the free drift case. Therefore the tests in beam seas are performed with free drifting model while the moored model setup was adopted for head seas. The results for ship motions are compared with those from a previous campaign giving an insight into repeatability and uncertainty of measurements. The roll decay of the ship in both intact and damaged conditions is analysed and the linear and quadratic extinction coefficients for the model and the ship scale are reported and detailed discussion on intact-versus-damaged ship roll damping behaviour is given. The results for the hull girder loads are presented for intact and damaged ship. An investigation of the nonlinear effects due to wave height variation in the range wave height to wave length from 1/50 to 1/22 on the shear force and bending moment values was carried out for a range of wave lengths to ship length ratios from 0.8 to 1.4. The results of the extensive campaign are compared against similar experimental studies forming a benchmark data for validation of numerical methods

Offshore wind farms : potential and applicability in the Southern Marmara Region, Turkey

In this study, applicability of offshore wind energy conversion systems in the Southern Marmara Region has been investigated. For this purpose, four different regions were selected and wind properties of the regions were assessed. Selected regions have been analysed by taking into account the wind data measured as mean daily time series. The wind data used in this study has been taken from Meteorological Data Archive and Management System of Turkish State Meteorological Service (TUMAS-TSMS). As a first step for the deployment of offshore wind farms in Turkey, the wind energy potential along the southern Marmara shoreline has been assessed. Combined with the regions wave climate properties and bathymetrical features, suitable locations for offshore wind energy farms are recommended. The outcome indicates that the regions surrounding Kapidag Peninsula can be used to deploy offshore wind turbine systems. More site-specific data and research is needed in order to augment this study