MARIN Maritime Research Institute Netherlands
Wageningen, Netherlands
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Agency: GTR | Branch: EPSRC | Program: | Phase: Training Grant | Award Amount: 3.94M | Year: 2014

The achievements of modern research and their rapid progress from theory to application are increasingly underpinned by computation. Computational approaches are often hailed as a new third pillar of science - in addition to empirical and theoretical work. While its breadth makes computation almost as ubiquitous as mathematics as a key tool in science and engineering, it is a much younger discipline and stands to benefit enormously from building increased capacity and increased efforts towards integration, standardization, and professionalism. The development of new ideas and techniques in computing is extremely rapid, the progress enabled by these breakthroughs is enormous, and their impact on society is substantial: modern technologies ranging from the Airbus 380, MRI scans and smartphone CPUs could not have been developed without computer simulation; progress on major scientific questions from climate change to astronomy are driven by the results from computational models; major investment decisions are underwritten by computational modelling. Furthermore, simulation modelling is emerging as a key tool within domains experiencing a data revolution such as biomedicine and finance. This progress has been enabled through the rapid increase of computational power, and was based in the past on an increased rate at which computing instructions in the processor can be carried out. However, this clock rate cannot be increased much further and in recent computational architectures (such as GPU, Intel Phi) additional computational power is now provided through having (of the order of) hundreds of computational cores in the same unit. This opens up potential for new order of magnitude performance improvements but requires additional specialist training in parallel programming and computational methods to be able to tap into and exploit this opportunity. Computational advances are enabled by new hardware, and innovations in algorithms, numerical methods and simulation techniques, and application of best practice in scientific computational modelling. The most effective progress and highest impact can be obtained by combining, linking and simultaneously exploiting step changes in hardware, software, methods and skills. However, good computational science training is scarce, especially at post-graduate level. The Centre for Doctoral Training in Next Generation Computational Modelling will develop 55+ graduate students to address this skills gap. Trained as future leaders in Computational Modelling, they will form the core of a community of computational modellers crossing disciplinary boundaries, constantly working to transfer the latest computational advances to related fields. By tackling cutting-edge research from fields such as Computational Engineering, Advanced Materials, Autonomous Systems and Health, whilst communicating their advances and working together with a world-leading group of academic and industrial computational modellers, the students will be perfectly equipped to drive advanced computing over the coming decades.

Raven H.C.,MARIN Maritime Research Institute Netherlands
PRADS 2016 - Proceedings of the 13th International Symposium on PRActical Design of Ships and Other Floating Structures | Year: 2016

To correct ship speed trials for limited shallow-water effects, Lackenby's method is currently recommended by the ITTC. This method appears to be based on very few and inadequate data. To replace it, a new procedure is proposed. It corrects separately for the effects of shallow water on the different components of ship resistance. These have been identified by computational studies.A simple algorithm is proposed to estimate a power increase for equal speed in shallow water. This new correction method has been applied to dedicated shallow-water trials for two ships and was found to perform much better than Lackenby's method.

Drummen I.,MARIN Maritime Research Institute Netherlands | Holtmann M.,DNV GL Maritime Advisory Services
Ocean Engineering | Year: 2014

Throughout the maritime world, considerable efforts have been spent on predicting loads associated with slamming. Up to now, little attention has, however, been paid to the accuracy of the translation from these loads to the structural responses. An important reason for this is that, in general, it is assumed that the uncertainties in the modeling of the hydrodynamic properties are larger than those related to the structural responses. To address this topic, the ISSC 2012 Dynamic Response committee, performed a benchmark study. The goal of this benchmark was twofold: on the one hand, the degree of variation in estimates produced by different methods and organizations was revealed; on the other hand, the deviations of the analyses were investigated by comparison with responses measured during model tests. From the results presented, it may amongst others be concluded that the shapes and frequencies of the two and three node, dry and wet and horizontal and vertical flexural vibration modes determined by the participants, were well in line with experimental results for four of the six participants. Computations considering an impulse induced by a regular head wave showed significant differences between the experiment, the different participants, and applied methods. © 2014 Elsevier Ltd. All rights reserved.

MARIN Maritime Research Institute Netherlands, Moro and Almossawi | Date: 2016-02-10

An nCycle e-bike frame includes two corresponding half-shells (1) and (2) which include an auxiliary cavity (1a) and (2a), battery hatch cavity (1b) and (2b), motor housing cavity (1c) and (2c), seat post column channel (1d) and (2d), steering column channel (1e) and (2e), steering column stopper (1f), rear fork (1g) and (2g), rear hub mounting (1h) and (2h), brake caliper mounting points (2j), outer membrane (1k) and (2k) and internal ribs (11), (21). A locking system comprised of two sliding pistons (29) and (30) and a locking mechanism (31) can be added. The crank electric motor (25) and battery (24) are enclosed between the two half shells (1) and (2), thus providing a smoother and safer structure for the rider. The integrated locking system and auxiliary hatch make the frame more flexible and easier to use compared to previous implementations.

Grin R.,MARIN Maritime Research Institute Netherlands
Journal of Ship Production and Design | Year: 2015

There is continuous research on analytical, numerical, and (semi)empirical methods to predict wave-added resistance. Most of this research focuses on a particular area, like motion-induced wave added resistance, wave-added resistance in short waves, or is limited to head seas only. The practical application of most methods is therefore often limited. Moreover, most methods require detailed information on hull lines and results are rather sensitive to the discretization of those hull lines. Since 2006, MARIN has been investigating the feasibility of empirical methods that do not have those limitations. They only require the main particulars to predict wave-added resistance. Within the Sea Trial Analysis Joint Industry Project (STA-JIP), a method was developed for the correction of wave-added resistance in head seas covering both the motion-induced and the wave reflection-induced component. This method was further refined and extended to all wave directions within the service performance analysis JIP (SPA-JIP) in 2008. This article presents the results of the comparison between the prediction methods and model tests for almost 50 different ships, comprising more than 1500 tests in regular and irregular seas.

Kaminski M.L.,MARIN Maritime Research Institute Netherlands | Bogaert H.,MARIN Maritime Research Institute Netherlands
International Journal of Offshore and Polar Engineering | Year: 2010

This paper describes the first full-scale tests on a real membrane containment system subjected to the action of breaking waves representative of sloshing impacts in LNG tanks. The waves were generated in a water flume using a wave focusing method. The tests were carried out within the Sloshel project, which is described in several accompanying papers. This paper focuses on describing the test method, the experimental setup and the post processing of the data collected in 110 tests; it explains how the project goals were translated into the design of the test setup and the instrumentation. Then it describes an extensive qualification of the data acquisition system and sensors. Emphasis is on the sensors developed within the project, such as pressure gauges and a novel optical sensor capturing the last stage of the sloshing impact. The test programme and some preliminary results are summarised. Conclusions are given regarding system performance, data quality and the use of data for achieving the project goals. Copyright © by The International Society of Offshore and Polar Engineers.

Koop A.,MARIN Maritime Research Institute Netherlands
Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE | Year: 2015

To determine shallow water effects on current loads for an LNG Carrier, CFD calculations with MARIN's CFD code ReFRESCO have been carried out. The CFD results are compared to model tests carried out in MARIN's Shallow Water Basin for the HAWAI JIP. The loads have been determined for three different water depth to draft ratio's, from relatively deep water to shallow water. For all water depths the difference in CY coefficient between the CFD results and experiments is 5-10%. Furthermore, the blockage effects from basin side walls are investigated. For shallow water it was found that the blockage effects are significant, i.e. 30-50%, and that they vary for different current headings. For deeper water the blockage effects are smaller than 5%. The influence of "towing" versus a "current" flow situation is also studied. In the experiments the model is towed through the basin leading to a relative velocity between the model and the basin floor. It is found that for shallow water the results for the "tow" situation are 10% lower than for the "current" situation. Lastly, preliminary results for full scale are presented. At full scale the current coefficients are found to be lower than at model scale. However, more investigations should be carried out at full scale to be able to draw definite conclusions. From the results presented in this paper it is concluded that shallow water effects on current loads can be accurately obtained with CFD. Furthermore, blockage effects and the influence of "towing" versus a "current" situation have been quantified and a first study into scale effects has been presented. © 2015 by ASME.

Van Der Ploeg A.,MARIN Maritime Research Institute Netherlands
MARINE 2015 - Computational Methods in Marine Engineering VI | Year: 2015

A procedure for optimizing the aft body of a ship for minimal power and best wake field quality is described, based on full-scale RANS computations possibly including free- surface effects. A flexible and effective definition of parametric hull form variations is used, based on interpolation between a limited number of basis hull forms. This keeps the dimension of the search space low, which enables to do systematic variations. For a test case in which the ship's wave making can be neglected it is shown that the grid dependence in the computed trends is low, and for a test case including free-surface effects it is demonstrated how the search space can be set up in such a way that a considerable decrease in required power can be obtained without spoiling the wake quality.

Gkikas G.D.,MARIN Maritime Research Institute Netherlands
Proceedings of the International Offshore and Polar Engineering Conference | Year: 2015

A nonlinear response amplitude operator (NRAO) that is able to model a wide class of nonlinear systems and structures, usually found in maritime and offshore applications, is developed. Its functional scheme is of the Volterra-series type and its order is explicitly dictated from the order of nonlinearity of the actual dynamical system. In addition, the proposed method is not bounded by any amplitude or frequency constrains and it can compute the response of a nonlinear system even for multi-chromatic excitations that consist of modes with significantly, or not, different amplitudes and frequencies. Copyright © 2015 by the International Society of Offshore and Polar Engineers (ISOPE).

Bosschers J.,MARIN Maritime Research Institute Netherlands
Journal of Physics: Conference Series | Year: 2015

Cavitating propellers generate pressure fluctuations on the hull of the ship. These pressure fluctuations are usually analyzed in the frequency domain using FFTs and the spectrum is composed of tonals at multiples of the blade passage frequency and a broadband part. The two are often considered separately but a relation between the two exists which has been investigated by theoretical signal analysis. It will be shown that the broadband part is related to the variability of the signal between blade passages and a simple procedure is proposed to quantify the variability in terms of amplitude and phase angle. The procedure has been applied to a data set obtained at sea trials.

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