This research focuses on identifying the most important stern shape aspects, with regard to resistance and propulsion power, of inland ships. Such information should help designers to determine which hull form aspect to adjust in case design requirements need them to do so. The information is obtained by firstly conducting a large series of CFD calculations, using the PARNASSOS code, for systematically varied inland ships. Next, response surface technologies are used to identify the most important aspects. This is done by sequentially adding and/or removing parameters from the response surface in order to find the combination of parameters that explains the majority of the variance in the performance data for the tested hull forms. Finally, an optimization algorithm is used to determine the optimal hull forms for varying displacement, showing which parameters should be adjusted preferably in order to increase (or decrease) ship displacement. This, specifically, should aid designers in making the trade-off between displacement (or cargo capacity) and energy consumption. @en

This paper covers the development, challenges, and initial lessons learned from the creation of a new block-based conceptual submarine design tool to support maritime graduate education at Delft University of Technology. The authors developed a design tool to assist students with the weight balancing, general arrangements creation, and automatic visualization of a military submarine. The tool is based in MS Excel and Rhinoceros 3D (Rhino). As an educational tool available to all students, there were certain constraints on the software platform that existed to ensure fair, open access to all students. This paper aims to describe the rationale behind how the current submarine design tool works, and some of the challenges the authors faced when implementing this tool in a 10 week complex marine design course. Lessons learned from both an educational and tool development perspective will be presented as well as areas for future improvements of the tool.@en

The ITTC57 correlation line, which is derived based on the assumption that the water in which ships advance is infinite deep and wide. However, for ships sailing in the waterway with limited water depth, the frictional resistance will be influenced leading to a decreasing accuracy of the prediction with this correlation line. In this study, a modification of the ITTC57 correlation line is proposed to correct the effects in very shallow water specifically for the flat area of the bottom of the ship. Under some assumptions, this area can be simplified to a 2D flat plate with a parallel wall close to it to study how the shallow water conditions of two interacting boundary conditions are affecting the flat plate friction coefficient. Computational fluid dynamics (CFD) calculations are applied to investigate how a friction line specifically in shallow water deviates from the conventional lines. Such deviations may severely affect the extrapolation of a ship model’s resistance to full scale and, therefore, the accuracy of ship’s performance prediction. Cases at ten Reynolds numbers from 10⁵ to 10⁹ are simulated on the 2D flat plate. Seven different distances between the flat plate and the parallel wall were chosen to generate various shallow water conditions, and consequently, a database including frictional resistance coefficients, Reynolds numbers and the distance between those two walls is built. Results indicate that thinner boundary layers are observed in shallow water conditions, and the scale effects which has a significant impact on resistance extrapolation are also observed. Furthermore, the assumption of the zero pressure gradients (ZPG) which is commonly used in deep water is no longer valid in extremely shallow ones. Finally, a modification for the ITTC57 correlations line considering shallow water effects is proposed, which is willing to improve the prediction of the frictional resistance of those ships with a large area of flat bottom and sail in shallow water.

@en

The manoeuvring performance of inland vessels is even more crucial than that of seagoing ships due to more complex navigation environment. One of the most effective possibilities to improve ship manoeuvrability is to change the rudder configuration. Twin or even quadruple rudders and high-lift profiles are widely applied to inland vessels. When inland vessels equip with multiple rudders, the interaction effects between the rudders affect the hydrodynamic characteristics of each rudder. This paper presents a study on these interaction effects using two-dimensional Reynolds-averaged Navier–Stokes (RANS) methods. Various twin-rudder and quadruple-rudder configurations with different profiles and spacing among the multiple rudders were studied. RANS simulations were performed with a k−ω SST turbulence model and a pressure-based coupled algorithm. Series of NACA, IFS and wedge-tail profiles were tested. Regression formulas have been proposed for the twin-rudder lift and drag coefficients. Finally, interaction effects on multiple rudder hydrodynamics have been summarised.@en

Inland ships continuously operate in restricted waters, where the depth and width are regularly less than twice the ship's draft and four times ship breadth, respectively. In restricted water, the flow around the hull changes compared to that in unrestricted water due to presence of the fairway bottom and sides, that lead to increased return flow, stronger squat effects and changes in the wave pattern produced by the ship. If these changes to the flow are significant, it is worthwhile to optimize the hull form for shallow or confined water rather than for unrestricted water. This paper specifically focuses on the effects of water depth on inland ship stern optimization. It presents the optimization of propulsion power for various water depths using a parametric inland ship stern shape, CFD and surrogate modeling. The change of parameter influence in different water depths is analyzed and explained by means of flow visualization. Using Pareto fronts, a trade-off is shown: propulsion power in shallow water can be decreased at the cost of increased propulsion power in deep water and vice versa.

@en

Inland vessels generally experience a resistance increment when the water in which they sail is extremely shallow. In this case, resistance extrapolation from ship model to full scale becomes complicated, and the traditional approaches do not often lead to satisfactory predictions. In this study, both numerical and experimental methods were applied to investigate the ship resistance, trim and sinkage in extremely shallow water. In the numerical calculations, the model initially has a trim and sinkage obtained from the model tests. The overset mesh technique was used to save the meshing effort. A 1/30 scaled model, which is only allowed to pitch and heave, was used in the model tests. It was found that, in extremely shallow water, the ITTC57 correlation line is not sufficient to extrapolate the resistance.@en

Shallow water effects change the flow around a ship significantly which can affect the optimum design of the hull. This paper describes a study into the optimization of the aft ship region for various water depths. The research focuses on variations of the following parameters of a hull form: The athwart ship’s propeller location, the tunnel top curvature, the flat-of-bottom shape in the stern region and the stern bilge radius. All hull form variants are valuated in 3 different water depths using a viscous flow solver, and a surrogate model is created for each water depth. Pareto plots are used to present the trade-off between the optimization for one or another water depth. Finally, specific hull forms are chosen and the differences in flow behavior among hull forms and water depths are explained.@en