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A study is presented on ship-bank interaction effects in which viscous-flow solvers are used to predict the hydrodynamic forces and moments on the ship. The ship under consideration is the KRISO Very Large Crude Carrier (KVLCC2). For this hull form, Flanders Hydraulics Research (FHR) has conducted shallow water model tests in their towing tank equipped with surface-piercing banks and a vertical quay wall. The forces and moments on the KVLCC2 model were obtained for various water depths and lateral distances to the banks. Additionally, the wave elevation was measured between the quay wall and the ship model. In this study, two different CFD codes are used to predict the loads on the KVLCC2 as a function of the water depth and lateral position in the channel. The effect of propeller suction and free surface modelling on the results is quantified. Furthermore, comparisons will be made with CFD results from literature and potential flow computations to highlight the benefits of each approach. It will be shown that with careful setup of the computations, reliable predictions of the ship-bank interaction effects can be obtained. [ABSTRACT FROM AUTHOR]

The aim of this research work is to develop a procedure including experimental measurements and advanced numerical simulations of fluid flow to address optimization problems in kayaking. The different steps preparatory to the optimization task are described: the use of experimental data on the hull kinematics to create a simplified, periodic but realistic kinematic model, the numerical simulation using this kinematics as an imposed hull motion, the a posteriori computation of the loads of the athlete acting on the hull. Finally, a verification of the whole chain is carried out, by solving the flow around the hull, which is now free to move according to the computed loads of the athlete. Some preliminary results of this on-going work are finally shown. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this research is to develop hydrodynamic models to enhance the knowledge of the propulsion efficiency in rowing. The flow around a rowing blade is a complex phenomenon characterised by an unsteady 3D behaviour, with violent free surface deformation including breakup and with a flexible shaft driven by a 6-DOF movement. The study uses experimental results obtained on an instrumented boat to perform CFD computations. All parameters are considered except the minor role played by the spin rotation of the shaft. The numerical results fit fairly well with experimental data given a high number of uncertainties. Once CFD computations fully validated, more accurate parametric models could be built and integrated in a rowing simulator which will help coaching staff in analysing and improving performance and training of athletes. Another considered possibility is the direct coupling between the rowing simulator and the CFD code. [Copyright &y& Elsevier]

The bow wave generated by a steadily advancing ship is considered for a family of fine ruled ship bows with rake and flare. This family of ship bows is defined in terms of four parameters: the ship draft D, the entrance angles a and a' at the top and bottom waterlines, and the rake angle δ. The corresponding bow wave similarly depends on four parameters: the draft-based Froude number Fand the three angles α, α′, and δ. An extensive parametric study, based on thin-ship theory, is performed to explore the variations of the water height Z0 at the ship stem X = 0, the location X0 (measured from the ship stem) of the intersection of the bow-wave profile with the mean free-surface plane Z= 0, and the bow-wave profile, with respect to the four parameters F, α, α′, and δ. This parametric study extends the previously reported similar study of the height Zb of the bow wave and the location Xb of the bow-wave crest. These two complementary parametric studies yield simple analytical relations, which extend relations given previously for wedge-shaped ship bows without rake or flare. In spite of their remarkable simplicity, the analytical relations given here yield bow waves that are comparable to computational fluid dynamics (CFD) waves given by Euler-flow calculations. The analytical relations, which explicitly account for the influence of the four primary parameters F, α, α′, and δ, can be used immediately-without hydrodynamic calculations-for ship design, notably at early design stages when the precise hull geometry is not yet known. The study also provides insight for ship bow design. Specifically, it suggests that a bow with positive rake and negative flare may be beneficial, and that a bulb located aft of the stem and integrated with the hull may be an advantageous alternative to a traditional bulb protruding ahead of the bow, in agreement with the results of a hull-form optimization analysis. [ABSTRACT FROM AUTHOR]

A fully-analytical theory that approximately predicts the size, shape and thickness of the overturning detached bow wave, and the width of the wavebreaking wake behind the plunging bow wave, generated by a ship with a fine bow that advances (at constant speed along a straight path) in calm water is reported. The theory yields simple analytical 'cause-and-effect' relations that provide useful physical insight and explicitly relate a ship's speed, draft, and main parameters characterizing the bow shape (entrance angles of the top and bottom waterlines, rake angle, flare) to the corresponding overturning bow wave and wavebreaking wake. Qualitative comparisons with experimental observations and CFD calculations show that while the elementary analysis underlying the theory cannot be expected to yield accurate predictions, the theory predicts trends correctly and provides practical estimates of the influence of basic ship design parameters (speed, draft, bow shape) on main characteristics of the overturning bow wave and the related wavebreaking wake created by a ship bow. [ABSTRACT FROM AUTHOR]

Installing an energy saving device such as a pre-swirl duct (PSD) is a major investment for a ship owner and prior to an order a reliable prediction of the energy savings is required. Currently there is no standard for how such a prediction is to be carried out, possible alternatives are both model-scale tests in towing tanks with associated scaling procedures, as well as methods based on computational fluid dynamics (CFD). This paper summarizes a CFD benchmark study comparing industrial state-of-the-art ship-scale CFD predictions of the power reduction through installation of a PSD, where the objective was to both obtain an indication on the reliability in this kind of prediction and to gain insight into how the computational procedure affects the results. It is a blind study, the KVLCC2, which the PSD is mounted on, has never been built and hence there is no ship-scale data available. The 10 participants conducted in total 22 different predictions of the power reduction with respect to a baseline case without PSD. The predicted power reductions are both positive and negative, on average 0.4%, with a standard deviation of 1.6%-units, when not considering two predictions based on model-scale CFD and two outliers associated with large uncertainties in the results. Among the variations present in computational procedure, two were found to significantly influence the predictions. First, a geometrically resolved propeller model applying sliding mesh interfaces is in average predicting a higher power reduction with the PSD compared to simplified propeller models. The second factor with notable influence on the power reduction prediction is the wake field prediction, which, besides numerical configuration, is affected by how hull roughness is considered. [ABSTRACT FROM AUTHOR]

One main concern in climate science is to reduce uncertainties on sea level predictions. In particular, these uncertainties depend on the quantification of the mass balance of polar ice caps including Greenland ice sheet. Iceberg calving at Greenland tide water glaciers accounts for up to half of ice losses at glacier termini. Glacier-height thin icebergs are unstable and their capsize exerts a force on the glacier front which generates a seismic wave recorded at stations at teleseismic distances (GLISN network on Greenland).The force of the iceberg on the glacier depends on the volume of the iceberg and the whole dynamic of the capsizing iceberg (Sergeant et al. GRL 2016). The global aim of this work is to retrieve information of the capsize dynamic based on seismic data to infer the volume and other characteristics of the icebergs. Iceberg capsize dynamics depends on complex phenomena: iceberg-water interactions, iceberg-glacier friction, glacier-sea floor friction, elasto-viscoplastic deformation of ice; and only little field data is available. Solving directly fluid flow, solid motion, and contact equations even in two dimensions is very costly and can hardly be used to generate catalogues and to solve inverse problem. Therefore, a simplified mechanical model of a capsizing iceberg in water has been developed based on few assumptions. The proposed model, named SAFIM (semi-analytical floating iceberg model) accounts for sea hydrodynamics only through hydrostatic pressure, pressure drag, and added mass, and it has been validated based on a separate state-of-the-art Computational Fluid Dynamics code which can handle free surface and arbitrary iceberg configurations. In SAFIM model, the pressure drag presents a very important effect to take into consideration in accurate modelling of the dynamic of the capsizing iceberg. The SAFIM model is used to invert seismic signals and to estimate the dimensions of capsizing icebergs for few well-documented events. [ABSTRACT FROM AUTHOR]