Modern Container Research Articles

Zelena perspektiva općeg i namjenskog kontejnerskog prijevoza od Azije do sjevernog Jadrana

Intermodal transport is often touted as an environmentally sustainable mode of transport, especially when considering its share of the total supply chain. This article addresses the topical and sensitive issue of supply chain assessment in terms of the carbon footprint and energy efficiency of external transportation from the point of production to the customer. The long transportation distances overseas and the variety of operational sea container services result in significant variations in delivery times from Asian markets. In addition, disruptive events such as the Covid-19 pandemic and the Ukraine conflict have led to longer transportation times and lower reliability of various maritime services. The study examines the variety of existing direct container services from Asia to the Northern Adriatic. In addition to the two direct container services already established, another dedicated container service has been established primarily to serve a large retail chain in the European market. The “newly established” container service is characterised by its limited port coverage and the use of relatively small container ships with a maximum capacity of 5.500 TEU. The comparisons between the services highlight the differences in transport time and greenhouse gas (GHG) emissions, as well as the energy efficiency of container transport. The study empirically confirms the widespread assumption that larger and modern container ships offer environmental benefits, provided that cargo space is used efficiently and ship operators adopt slow steaming. However, the study also highlights the significant differences in GHG emissions between different services and emphasises the need for more comprehensive information and awareness among cargo owners to design sustainable supply chains.

Numerical Reconstruction in Maritime Archaeology

Numerical reconstruction is the process of modeling, analyzing, and evaluating the performance of structures or a sequence of events using the finite element method and other numerical engineering methods. Although numerical analysis is used extensively in contemporary engineering problems, it can be equally useful in the study of ancient structures and events of the past. The materials and design of structures are different, e.g., when comparing a modern containership with an old galleon, but the main problem to be solved is essentially the same—will the ship sail efficiently and safely for many years? This paper aims to provide an overview of recent achievements in numerical reconstruction in maritime archaeology. Since it is clearly an interdisciplinary activity, research is often carried out within a specific project by project team members or interested groups of researchers. While the paper aims to provide a comprehensive overview of such efforts, special attention is paid to activities related to the AdriaS (Archaeology of Adriatic Shipbuilding and Seafaring) and NEREAS (Numerical Reconstruction in the Archaeology of Seafaring) projects supported by the Croatian Science Foundation, to which the authors actively contribute.

Experimental and numerical investigations of effects of ship superstructures on wind-induced loads for benchmarking

For a representative large modern containership, the effects of a deck container arrangement on the wind-induced loads were systematically investigated using physical model tests and numerical computations. Numerical simulations based on various turbulence models were performed to validate our predictions against comparative wind tunnel measurements. Not only standard two-equation turbulence models of the unsteady Reynolds-Averaged Navier–Stokes (URANS) equations solver but also the improved delayed detached eddy simulation (IDDES) and large eddy simulation (LES) turbulence models were used to determine their limits in the prediction of aerodynamic loads. Systematic discretization studies ensured adequate discretization independent predictions. With URANS, numerically predicted wind forces and moments in near-head and near-tail winds were compared favorably with the measured data. However, in oblique winds, URANS predictions deviated from measurements. In oblique winds, flow separations were pronounced; therefore, the flow was strongly transient. Consequently, a two-equation turbulence model was inappropriate. With IDDES, more accurate predictions were achieved, especially in oblique winds. With LES, although the computational effort was high, the agreement of the computed forces and moments with the measured values was superior. Flow details were also presented and discussed. The container arrangement on deck showed major effects on aerodynamic forces and moments. A tarpaulin covering the containers on deck reduced wind resistance by up to 70%.

CFD-based empirical formulae for squat prediction of modern container ships

ABSTRACT An extensive Computational Fluid Dynamics (CFD) based study has been undertaken to develop a set of empirical formulae for squat prediction suitable for modern container ships in laterally-unrestricted shallow water. Previous work has quantified the effect of various ship principal particulars on midship sinkage and trim. The current study expands on the previous work to provide further quantifications for ship speed and water depth. Multiple linear regression analysis is then performed on the dataset to produce empirical equations for sinkage and trim. Predictions using the new set of formulae correlate well with the original dataset as well as new datasets which are within the limits of applicability. Predictions using the new formulae tend to be more accurate than existing empirical methods for the cases tested. Hence, the new set of formulae is a useful tool to provide reliable, rapid squat assessment and is suitable for implementation into real-time ship-handling simulator mathematical models.

AIS-Enabled Weather Routing for Cargo Loss Prevention

The operation of any vessel includes risks, such as mechanical failure, collision, property loss, cargo loss, or damage. For modern container ships, safe navigation is challenging as the rate of innovation regarding design, speed profiles, and carrying capacity has experienced exponential growth over the past few years. Prevention of cargo loss in container ship liners is of high importance for the Maritime industry and the waterborne sector as it can lead to potentially disastrous, harmful, or even life-threatening outcomes for the crew, the shipping company, the marine environment, and aqua-culture. With the installment of onboard decision support system(s) (DSS) that will provide the required operational guidance to the vessel’s master, we aim to prevent and overcome such events. This paper explores cargo losses in container ships by employing a novel weather routing optimization DS framework that aims to identify excessive motions and accelerations caused by bad weather at specific times and locations; it also suggests alternative routes and, thus, ultimately prevents cargo loss and damage.

The Use of Artificial Neural Networks to Determine the Engine Power and Fuel Consumption of Modern Bulk Carriers, Tankers and Container Ships

The 2007–2008 financial crisis, together with rises in fuel prices and stringent pollution regulation, led to the need to update the methods concerning ship propulsion system design. In this article, a set of artificial neural networks was used to update the design equations to estimate the engine power and fuel consumption of modern tankers, bulk carriers, and container ships. Deadweight or TEU capacity and ship speed were used as the inputs for the ANNs. This study shows that even a linear ANN with two neurons in the input and output layers, with purelin activation functions, offers an accurate estimation of ship propulsion parameters. The proposed linear ANNs have simple mathematical structures and are straightforward to apply. The ANNs presented in the article were developed based on the data of the most recent ships built from 2015 to present, and could have a practical application at the preliminary design stage, in transportation or air pollution studies for modern commercial cargo ships. The presented equations mirror trends found in the literature and offer much greater accuracy for the features of new-built ships. The article shows how to estimate CO2 emissions for a bulk carrier, tanker, and container carrier utilizing the proposed ANNs.

Computational Fluid Dynamics Prediction of the Resistance of Modern Container Ships

Computational Fluid Dynamics Prediction of the Resistance of Modern Container Ships

Numerical parametric study of medium sized container ship squat

A numerical investigation has been undertaken to study the impact of varying a container ship's principal particulars on squat in shallow water. Initially, a statistical review of the principal particulars of commonly operating container ships is discussed and used to determine the range for length-to-beam ratio (L/B), beam-to-draft ratio (B/T) and block coefficient (CB) to be analysed systematically. Unsteady RANS CFD simulations are adopted to predict the squat of a self-propelled S175 container ship where the approach is successfully verifed and validated against benchmark experimental data. The same methodology is adapted to a KCS hull as a representation of modern container ships and systematic parametric transformations are conducted to study the effect of varying L/B, B/T and CB on squat. The results show that sinkage and trim are inversely related to L/B while sinkage is independent of B/T, but trim is inversely related to B/T. Sinkage is also found to be independent of CB whereas trim magnitude becomes increasingly stern down when CB increases due to the nature of the parametric transformations in this study. It is identified in this study that the relative position of the LCB to the LCF is responsible for the change in trim direction. Most empirical predictions show similar trends for varying L/B and B/T but contradicting trends are observed for varying CB.

Parametric roll vulnerability of ships using Markov and Melnikov approaches

The designs of modern container ships, roll-on–roll-off vessels and cruise vessels have evolved over the years, and in recent times, some of them have been observed to experience dynamic instabilities during operation in the open ocean. These catastrophic events demonstrate that satisfying prescriptive stability rules set forth by International Maritime Organization (IMO), national authorities (e.g., Coast Guard) and other classification societies are not sufficient to ensure dynamic stability of ships at sea. In light of these events, IMO is organizing efforts to make way toward a second generation of intact stability criteria that are better equipped to deal with these dynamic instabilities. This paper discusses the development of such a tool for parametric rolling in a realistic random seaway, which is one of the critical phenomena identified by IMO. In this study, a previously developed analytical model for roll restoring moment, which was found to be effective in modeling the problem of parametric roll, is analyzed using the Melnikov approach. The stability of the system is quantified in terms of rate of phase space flux of the system. This approach is further compared with another technique known as the Markov approach that is based on stochastic averaging and quantifies stability in terms of mean first passage time. The sensitivity of both of these metrics to environmental parameters is investigated. Finally, the nature of random response is analyzed using Lyapunov exponents to determine whether the vessel exhibits any chaotic dynamics.

Hydrodynamic Design Study on Ship Bow and Stern Hull Form Synchronous Optimization Covering Whole Speeds Range

The main objective of this article is to describe an innovative methodology of synchronous local optimization which considers the whole ship speed range being presented for a KRISO Container Ship (KCS). Parametric form approaches are adopted by employing a fairing B‐spline curve in order to generate variants of the bow and stern of forms using form design parameters modified, resulting in an optimization system based on NSGA‐II. The total resistance is calculated by the Rankine source panel method and the empirical formula which agrees well with the corresponding experimental data and further acquires validation with the overall error of 2.0%. Accordingly, the ship forepart and stern form have been optimized under conditions of the single design speed and whole speeds range based on the considerations of generally distributed and variable operational speeds for the operating characteristics of modern container ships synchronously. The optimized result presents well‐balanced drag reduction benefits which averagely remain above 4.0% of ship resistance decrease. Compared to the traditional optimization process which is based on a specific design speed, the newly developed method is more practical and effective in both automation and integration.

Study on added resistance of a ship under parametric roll motion

Parametric roll of ship is a rare event occurring in specific conditions, but it can cause the dynamic roll instability. Since this phenomenon is dependent on ship speed and wave frequency, the development of roll motion and the resultant added resistance which can cause speed change should be considered simultaneously when parametric roll occurs. This paper considers a numerical study on the added resistance of a modern containership under parametric roll. A time-domain Rankine panel method adopting a weakly nonlinear formulation is adopted to obtain ship motions and added resistances in waves. Seakeeping computations in regular head-sea conditions are performed with and without parametric roll, and the increment of added resistance is investigated with regard to the components classified in the direct pressure integration method. Furthermore, according to the decoupling phenomena between the components of the vertical motions and the roll motion, a correlation between the parametric roll and the added resistance is derived. Lastly, a simple prediction method for the added resistance in irregular parametric roll motion is suggested based on the correlation, and its accuracy and efficiency are discussed by comparing the prediction with the results of the direct numerical computation.

A simplified 2½-degree of freedom time-domain model with non-linearity for the simulation of parametric roll

In this paper, a simplified 2½-degree of freedom time-domain numerical method with non-linearity is developed, presented in detail and validated for simulating parametric roll. The method is termed 2½-degree of freedom since; it first linearly couples heave and pitch via a three-dimensional frequency-domain pulsating source method. The roll equation of motion is – then – solved in the time domain with, non-linear damping and non-linear parametric excitation taken into account and formulated in terms of heave-pitch-wave profile influence on roll. In other words, heave and pitch motions influence roll but roll motion does not influence heave and pitch back hence, the term 2½-degree of freedom. The mathematical formulation of the proposed method is presented in detail and has been developed into an in-house numerical model. Subsequently, the numerical model is applied to a modern container ship. Experimental results from the literature are utilized for validation. Predicted results show very good agreement with experiments and demonstrate the ability of the proposed method to accurately capture the influence of various parameters affecting parametric roll.

Technological Development of Container Ship - Historic Approach

U ovom radu obradit će se koncept kontejnerskog broda, njegovi začeci i prihvaćanje na tržištu. Pratit će se razvoj broda i tehnologije s posebnim osvrtom na značajke modernih kontejnerskih brodova koji su mu omogućili da postane neizostavan dio globalno ekonomije. Statistički će se prikazati stanje svjetske kontejnerske flote, glavne kontejnerske luke te plovidbeni pravci.

Suvremeni kontejnerski brodovi i fenomen parametrijskog ljuljanja

Modern container ships are designed to meet the requirements of increased capacity and to achieve high speed, whereby causing a relatively low block coefficient. Due to such features, they become most susceptible to the impact of parametric rolling. In addition to the structural features of the ship, parametric rolling is also affected by characteristics of successive waves either from the fore or aft part. The appearance of parametric rolling can threaten the people on board, the ship and her cargo. Therefore, the IMO has been actively involved in providing support for study of this phenomenon. The systems, which are used for prevention and mitigating the consequences of ship’s parametric rolling, can be regarded as systems for monitoring the characteristics of waves and those of the ship that have an effect on the occurrence, and also as systems seeking to reduce ship’s rolling that occurs as a consequence of the observed phenomena. The aim of this paper is to define the characteristics of container ship, and the characteristics of waves that directly affect the appearance of ship’s parametric rolling. The paper also analyzes technical solutions that can be used to obtain data relevant for the development and technical solutions which may reduce the effect of the phenomenon.

Calculation of Horizontal Sectional Loads and Torsional Moment

Horizontal sectional loads (horizontal shear force and horizontal bending moment) and torsional moment are more difficult to predict with potential flow methods than vertical loads, especially in stern-quartering waves. Accurate computation of torsional moment is especially important for large modern container ships. The three-dimensional (3D) seakeeping code GL Rankine has been applied previously to the computation of vertical loads in head, following and oblique waves; this paper addresses horizontal loads and torsional moment in oblique waves at various forward speeds for a modern container ship. The results obtained with the Rankine source-patch method are compared with the computations using zero-speed free-surface Green functions and with model experiments.

Linear and Nonlinear Sectional Loads With Potential and Field Methods

A Rankine source method is applied to predict linear and weakly nonlinear sectional loads of a modern container ship. The method uses solution in the frequency domain, linearized with respect to wave amplitude about the nonlinear steady flow due to forward speed, which accounts for the nonlinear free-surface conditions, ship wave, and dynamic trim and sinkage. Weak nonlinearity of the sectional loads in waves (e.g., hogging-sagging asymmetry) is taken into account by pressure extrapolation and integration up to the estimated actual water line. The sectional forces obtained with this method are compared with the results of other methods, including (1) linear Rankine panel method, where flow due to waves is linearized about the double-body flow, (2) linear zero-speed Green function method with correction for forward speed, (3) fully nonlinear simulations based on field-based solution of Reynolds-averaged Navier–Stokes (RANS) equations, and (4) model tests. Comparison with RANS solution and model tests shows, that the proposed method can accurately predict sectional loads for small to moderate wave heights.

A Rankine Panel Method for Added Resistance of Ships in Waves

A new Rankine panel method and an extended Reynolds-Averaged Navier–Stokes (RANS) solver were employed to predict added resistance in head waves at different Froude numbers of a Wigley hull, a large tanker, and a modern containership. The frequency domain panel method, using Rankine sources as basic flow potentials, accounts for the interaction of the linear periodic wave-induced flow with the nonlinear steady flow caused by the ship's forward speed in calm water, including nonlinear free surface conditions and dynamic squat. Added resistance in waves is obtained by the pressure integration method. The time domain RANS solver, based on a finite volume method, is extended to solve the nonlinear equations of the rigid body six-degrees-of-freedom ship motions. The favorable comparison of the panel and RANS predictions demonstrated that the Rankine method is suitable to efficiently obtain reliable predictions of added resistance of ships in waves. Comparable model test predictions correlated less favorably, although the overall agreement was felt to be acceptable, considering the difficulties associated with the procedures to obtain accurate measurements.

Effect of Container Stack Arrangements on the Power Optimization of a Container Ship

When considering the design of a ship, an important objective is to always try and develop one that allows for maximum cargo capacity with the lowest propulsion power requirement while providing a sufficient amount of strength and stability for its safe operation. The ship with the lowest propulsion power consumes the least amount of fuel and produces the lowest amount of exhaust gas that may be harmful to the environment. In some cases, the aerodynamic resistance can be neglected, but for a high speed vessel such as a modern containership, the air resistance can be in the range of 2% to 10% of the total resistance. Aerodynamic resistance can therefore have a significant effect on power requirements and is strongly influenced by the height, breadth, and the number of container stacks on the deck. The freeboard, beam of the ship, deck house design, ship speed, wind speed, and water flow direction will also contribute significantly to a ship's resistance and required propulsive power. This paper outlines the application of computational fluid dynamic simulation as a design tool to find a strategy for the optimal arrangement of the container stacks on deck so that the vessel uses the lowest effective propulsion power to achieve a fuel efficient ship. It is deduced that an optimal stack arrangement can reduce air resistance by about 30%.

Parametric rolling prediction in irregular seas using combination of deterministic ship dynamics and probabilistic wave theory

In recent years there have been reports of serious accidents of parametric rolling for modern container ships and car carriers. For avoiding such accidents, a prediction method of parametric rolling in irregular seas is required. Since parametric rolling is practically non-ergodic, repetitions of numerical simulations or experiments could be not feasible to ascertain the behaviour. Therefore, in this paper, a method combining a stochastic approach with a deterministic approach in order to estimate the probabilistic index without such simple repetitions is developed. The ship's response in regular seas is estimated by solving an averaged system of the original 1-DoF roll model, and random waves necessary for occurrence of parametric rolling is achieved by using Longuet-Higgins’s or Kimura’s wave group theory. As a result, a fast and robust computation method of the probabilistic index is established. Finally, it is concluded that the proposed method is considered to be one of the useful tools for discussing the new IMO Intact Stability Code.

Hydrodynamic characteristics of pile supported skirt breakwater models

Facilities for handling large draft vessels, modern container ships and tankers have become essential due to the rapid growth in marine traffic. A pile supported skirt breakwater (PSSB) is one of the most promising concepts that could fulfill this requirement as PSSBs are environment friendly and economical for locations where tidal fluctuations are large and soil conditions are poor compared to other types of conventional breakwaters. The structure consists of an impermeable barrier piercing the free surface and extending up to a certain depth of submergence. The barrier which is responsible for attenuating the incident waves through partial reflection is supported on closely spaced concrete or steel piles. The barrier would consist of pre-cast elements that are connected to the piles on site. A numerical model based on the Eigen function expansion theory for linear waves to investigate the reflection and transmission characteristics of a PSSB consisting of single and double rows has been developed. The wave run-up on the skirt of the front row as well as the oscillation of the water surface in between the two rows was also computed. The results on the above stated parameters are reported as a function of wave and structural parameters in a dimensionless form. The numerical results are compared with experimental results and the agreement in general is found to be good.