Upon entering shallow waters, ships experience a number of changes due to the hydrodynamic interaction between the hull and the seabed. Some of these changes are expressed in a pronounced increase in sinkage, trim and resistance. In this paper, a numerical study is performed on the Duisburg Test Case (DTC) container ship using Computational Fluid Dynamics (CFD), the Slender-Body theory and various empirical methods. A parametric comparison of the behaviour and performance estimation techniques in shallow waters for varying channel cross-sections and ship speeds is performed. The main objective of this research is to quantify the effect a step in the channel topography on ship sinkage, trim and resistance. Significant differences are shown in the computed parameters for the DTC advancing through dredged channels and conventional shallow water topographies. The different techniques employed show good agreement, especially in the low speed range

Historically, the prediction ship resistance has received its fair share of attention by the scientific community. Yet, a robust scaling law still lacks, leaving testing facilities to rely on experience-based approaches and large datasets accumulated from years of operation. Academia's concern regarding this has not led to an extrapolation procedure, capable of bearing scrutiny adequately. One way to circumvent what has become the bane of the study of ship resistance is to perform Reynolds averaged Navier-Stokes (RANS) simulations directly in full-scale. The rapid advent of such methods has meant that confidence levels in predictions achieved by RANS simulations are low. This paper explores and demonstrates scale effects on the constituent components of ship resistance by performing a geosim analysis using a Computational Fluid Dynamics approach. Emphasis is placed on challenging the assumptions imposed as part of the currently accepted ship resistance extrapolation procedure. Our results suggest that a high degree of uncertainty exists in the calculated full-scale resistance depending on the approach taken towards its evaluation. In particular, scale effects are demonstrated in wave resistance, while free surface effects are palpable in the frictional resistance.

With the rapid advent of computational methods in all fields of engineering, several areas have emerged as significant sources of ambiguity. Among these is the selection of a turbulence model to close the Reynolds averaged Navier-Stokes equation. In ship hydrodynamics, this has been particularly difficult to resolve due to the complex nature of the problem. Furthermore, there are a wide variety of turbulence models all claiming superiority. Thus, navigating to the correct choice is a subject of experience. The present study aims to alleviate the ambiguity inherent in the field. This is done by performing a series of tests on the turbulence models and comparing the integral outcomes with experimental results. Specifically, shallow water cases are chosen due to the additional layer of complexity associated in the prediction of parameters of interest. The results are analysed via a modified bivariate plot, which reveals a strong candidate for the optimum choice of turbulence modelling. The assessment simultaneously takes into account resistance and sinkage, in addition to consistency across different casestudies. The time per iteration also points towards the same candidate, identified as the standard k-ω model, as a good choice within the software used to perform the analysis. The results also suggest that pressure resistance and its constituent components are not coupled with the turbulence model. On the other hand, frictional resistance is highly dependent on the closure selected and is identified as the main contributor to deviations with regards to experimental values. Abe et al. (1994) proposed a modification of the standard k-ε model, henceforth referred to as 'AKN'

In international shipping, there are several waterways that are widely viewed as bottlenecks. Among these is the Suez Canal, where recent expansions have taken place. Although the Suez Canal has a high importance in international shipping, little research has been carried out in maximising the number of ships capable of traversing for a set period of time. The present study aims to examine hydrodynamic phenomena of ships advancing through the Suez Canal in the allowed speed range to determine the relative effects of the canal depth and /or width restrictions on the overall ship sailing performance. A rectangular canal is also included as a reference to gauge the effects of varying canal cross-section. The present study combines experimental, numerical, analytical and empirical methods for a holistic approach in calm water. As a case-study, the KCS hullform is adopted, and analysed experimentally, via Computational Fluid Dynamics, using the slender body theory, and empirical formulae. The results reveal strong coupling between the canal's cross section and all examined parameters.

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