This article investigates how speakers in maritime technologically mediated interaction utilize pre-scripted interaction. The analysis uses micro-analytical methods that have not been used in the analysis of maritime interactions since the study by Bailey et al. (2006). In contrast to Bailey et al. (2006) who have analysed interactions between co-located speakers on board ships, this article analyses interactions between speakers who are not co-located. Micro-analytical methods can shed light on sense-making practices that speakers display in pre-scripted user-device interaction as pointed out by Arminen (2005). The article advances the observations of Bailey et al. (2006) regarding the ‘confirmatory form’ that they found predominant in co-located bridge team interaction. A ‘confirmatory form’ is a speaker display of the pre-script1 called a ‘readback’ (IMO SMCP, 2001), that speakers show when verifying information. The analysis shows that the structure of the ‘readback’ is used by speakers, is dependent on reflexive user-device interaction and involves a situated rule-following (Wittgenstein, 1958). The article then argues against the findings in The MARCOM Project (1999) that advocates that spoken interaction should be done away with completely as a way of promoting safe navigation, and concurs with studies in aviation research, that show how verbal interaction is an essential part of the situated understanding that takes place when performing institutional tasks (Sanne, 2003; Nevile, 2004a; Falzon, 2008, 2009).
This study presents a detailed quantification of how flow orientation affects mass transfer and frictional resistance in periodically confined channels, offering novel insights into the physical similarity relations governing these phenomena. We constitute that the Sherwood number and friction factor adhere to universal scaling laws of the form Sh = A1+B sin(2α) Re1 2 and f = A1+B sin(2α) Re−1 2 , where α depicts the orientation of the periodically confined channel. It is found that the flow orientation and the cross flow velocity independently affect both, the Sherwood number and the friction factor. A key contribution of this work is the explicit characterization of the flow orientation: a 45° rotation of the flow relative to the spacer structure increases the Sherwood number by nearly 25%, while the friction factor rises by approximately 20%. These findings highlight a fundamental trade-off between mass transfer enhancement and flow resistance, suggesting that any process optimization must carefully balance the gains in mixing efficiency against the increased energy dissipation. This study provides a robust framework for further investigations into how periodic geometrical constraints influence transport processes in complex flow systems.
Since time-domain simulations of wave energy converters are computationally expensive, how can we analyse their dynamics and test wide ranges of design variables, without simplifying the physics involved? One possible solution is the use of General Polynomial Chaos (gPC). GPC provides computationally efficient surrogate models for partial differential equation based models, which are particularly useful for sensitivity analysis and uncertainty quantification. We demonstrate the application of gPC to study the dynamics of a wave energy converter in an operational sea-state, when there is uncertainty in the values of the stiffness and damping coefficient of the power take-off.
A coupling between a dynamic mooring solver based on high-order finite element techniques (MooDy) and a radiation-diffraction based hydrodynamic solver (WEC-Sim) is presented. The high-order scheme gives fast convergence resulting in high-resolution simulations at a lower computational cost. The model is compared against a lumped mass mooring code (MoorDyn) that has an existing coupling to WEC-Sim. The two models are compared for a standard test case and the results are similar, giving confidence in the new WEC-Sim-MooDy coupling. Finally, the coupled model is validated using experimental data of a spread moored cylinder with good agreement.
Until now, wave-energy developers have focused on designing large machines for utility-scale electricity generation. While many concepts with good capture performance have been devised, significant commercial success has yet to be achieved in this market. Smaller wave energy converters (WECs) for specialist uses have received less attention. Emerging applications for these machines include powering sensors for ocean monitoring and providing energy for recharging maritime autonomous vehicles. Small reliable floating WECs can provide both the low levels of power required for these applications, and a surface platform for satellite
communications. Here, the key idea is to reduce costs and increase human safety by deploying small WECs to perform tasks that would otherwise require a ship. Developing small WECs for specialist uses provides a fast route to market, thereby creating a viable financial and technical base for the development of larger devices for applications where more power is required. This paper reports early results of time- and frequency-domain simulations of a compact WEC designed for monitoring the ocean environment.
Port selection is of vital importance for both port operators and shipping lines. In this contribution, an Automatic Identification System (AIS) big data approach is developed. This approach allows identifying container ships using only AIS data without the need for supplementary information from commercial databases. This approach is applied to investigate the port selection statistics of container ships between Shanghai and Ningbo Zhoushan Port, two of the largest ports in the world in terms of calling frequency, to generate practical insights. Results show that: i) the ratios among large ships, medium ships and small ships of these two ports are both approximately 1: 4: 5; ii) these two ports both have an exclusive (i.e., more feeder ports covered in geographical coverage) and intensive (i.e., more feeder ships deployed in shipping service frequency) collection and distribution network mainly consisting of small ships, but that of Shanghai is more intensive; iii) in terms of ultra-large ships over 380 m, Shanghai has accommodated an extra 18.5% compared to that of Ningbo Zhoushan, this indicates Shanghai's attraction for such vessels in global fleet deployment; iv) the feeder network between Shanghai and Ningbo Zhoushan is weak, and their relationship is actually in competition; v) Ningbo Zhoushan could offer more choices for ultra-large container ships (over 380 m), which implies its greater potential in future port competition; vi) when the depth of channels and berths is sufficient, the distance to hinterland and the convenience of a collection and distribution network begin to get more important in port selection. The empirical findings unveil the decision-making of container lines, competition between ports and implications for shipping policy.
Collaborative spatial decision support tools can contribute with setups for including stakeholders into marine spatial planning (MSP) processes with the purpose of increasing trust in planning outcomes, facilitate knowledge co-creation and shared planning goals, and provide transparent, scientific, inclusive, and technical foundations for planning. A new collaborative spatial decision support setup based on the combination of functionalities from two spatial decision support tools called SEANERGY and Baltic Explorer was designed for and tested in a workshop in 2020 targeted local authorities, NGOs, and citizens in Denmark with an interest in MSP. While the setup needs further testing among a wider span of stakeholders to support a pluralistic approach, the findings illustrate promising potentials from ranking conflicts and synergies in collaborative settings to make marine activity interests spatially visible in MSP and gain an overview of opportunities for sea use multi-functionality in context-based, interactive, goal-oriented stakeholder processes. The use of a visual platform such as Baltic Explorer to systematically explore locations of marine uses was positively evaluated to facilitate the workshop conflict-synergy discussions. Challenges relate to how to deal with disagreements on conflict-synergy scores and the subjectivity of opinions, but the demonstrated flexible, quick, transparent way to test the sensitivity of spatial patterns to differences in input conflict-synergy scores is found to provide a promising setup for including stakeholder opinions through collaborative settings, a setup adjustable to supplementary large-scale, individual, more representative surveys as well.
Normal flow past flat plates at high Reynolds numbers appears in various engineering contexts. To accurately model such flows for slender plates in Computational Fluid Dynamics requires scale-resolving rather than scale-modelling methods. The present paper uses Detached-Eddy Simulation to investigate the influence of plate corner curvature on global flow quantities such as the time-averaged drag coefficient. The effect of corner curvature is mapped and collated with the literature. Solution verification is carried out to quantify the numerical uncertainty. The time-averaged drag coefficient increases significantly between semi-cylindrically rounded (〈𝐶〉=2.28) and sharp-cornered (〈𝐶〉=2.42) plates.
Wave excitation tests on a fixed sphere with the center at the still water level were carried out with three different physical wave basin setups. The tests were completed as a continued effort of the working group OES Wave Energy Converters Modeling Verification and Validation to increase confidence in numerical models of wave energy converters by generation of accurate benchmarks datasets for numerical model validation. An idealized test case with wave excitation of a fixed sphere to be used with the benchmarks was formulated. The three investigated physical wave basin setups included: 1) a six degree-of-freedom load cell mounted to the top of the sphere, 2) a bending beam force transducer mounted to the top of the sphere, and 3) a system of six pretensioned wires mounted to the top and bottom of the sphere with force transducers attached to each wire. The aim of the present paper is to identify the best representation of the idealized test case. To this end, the three experimental setups are inter-compared in terms of dynamic properties, sensitivity, and disturbances of the water phase from the presence of measurement equipment. Low inter-experiment variability was disclosed, ie, 5-8% depending on wave-nonlinearity, indicating accurate representations of the idealized test case across all setups. Setup 3 was found to be the more accurate representation and further work with this setup to release a public benchmark dataset was planned.
Accurate prediction of wave transformation is key in the design of coastal and nearshore structures which typically depends on numerical models. Turbulent and rotational effects call for the use of Computational Fluid Dynamics (CFD) solvers of which a large range of formulations including free surface treatments exists. Physical wave flume tests of wave propagation over a submerged bar with various levels of nonlinearity, regularity, and wave-breaking, dedicated to numerical model benchmarking or validation, were carried out in the Ocean and Coastal Engineering Laboratory of Aalborg University. Three fundamentally different CFD models each widespread within their category are benchmarked against the experimental data. The CFD models are based on (i) the Volume of Fluid (VoF) based interFoam solver of OpenFOAM, (ii) the sigma-transformation solver of MIKE 3 Waves Model FM, and (iii) the weakly compressible delta-SPH solver of DualSPHysics. Accuracy of the numerical models is assessed from surface elevation time series, evaluation metrics (averaged errors on surface elevations, amplitudes, phases, and wave set-up), and spectral analyzes to calculate the amplitude and phase contents of primary and higher-order components along the wave flume. Applicability is assessed from computational costs and ease-of-use factors such as the effort to configure the numerical models and achieve convergence. In general, the numerical models have high correlation to the physical tests and are as such suitable to model complex wave transformation with an accuracy sufficient for most coastal engineering applications. The VoF model performs more accurately under the turbulent conditions of breaking waves, increasing its relative accuracy in the prediction of downwave surface elevation. The sigma transformation model has simulation times one to two orders of magnitude lower than those of the VoF and SPH models.