VIRTUE : integrating CFD ship design

Novel ship concepts, increasing size and speed, and strong competition in the global maritime market require that a ship's hydrodynamic performance be studied at the highest level of sophistication. All hydrodynamic aspects need to be considered so as to optimize trade-offs between resistance, propulsion (and cavitation), seakeeping or manoeuvring. VIRTUE takes a holistic approach to hydrodynamic design and focuses on integrating advanced CFD tools in a software platform that can control and launch multi-objective hydrodynamic design projects. In this paper current practice, future requirements and a potential software integration platform are presented. The necessity of parametric modelling as a means of effectively generating and efficiently varying geometry, and the added-value of advanced visualization, is discussed. An illustrating example is given as a test case, a container carrier investigation, and the requirements and a proposed architecture for the platform are outlined

Numerical study of asymmetric keel hydrodynamic performance through advanced CFD

The hydrodynamics of an asymmetric IACC yacht keel at angle of yaw are presented using simulations performed by advanced computational fluid dynamics using state-of-the-art software. The aim of the paper is to continue working on the improvement of numerical viscous flow predictions for high-performance yachts using Large Eddy Simulation and Detached Eddy Simulation on unstructured grids. Quantitative comparisons of global forces acting on the keel and wake survey are carried out. Qualitative comparisons include flow visualisation, unsteady and separated flow and other features. Star-CCM+ and the trimmed cell method give better forces and wake prediction compared to the unstructured mesh of ANSYS Fluent. Both solvers give good flow visualisation near and far field of the keel

HPC and CFD in the marine industry: past, present and future

This paper explores the use of Computational Fluid Dynamics (CFD) applications on High Performance Computing (HPC) platforms from the perspective of a user engaged in Naval Architecture research. The paper will consider the significant limitations which were imposed on research boundaries prior to present HPC capabilities, how this impacted development in the field and the implications for industry. One particular example is the costly experimental testing which, due to resource constraints, is generally restricted to model scale. It will then present an overview of the numerical simulation capabilities using current HPC performance and capability. With the increase of computational power and capacity, CFD simulations are proving to be more accurate and reliable. Being relatively cheaper and more time efficient, numerical methods are becoming the preferred choice within the industry compared to traditional experimental tests. Nevertheless, certain experimental procedures cannot be numerically replicated with the current levels of computational capacity. The future needs and challenges of research and development will be outlined and discussed, highlighting the significant impact exascale computing will have in the field

A comparison of experimental and numerical behaviour characteristics of a ship entering a lock using benchmark test data

This paper discusses several papers that were presented at the 3rd International Conference on Ship Manoeuvring in Shallow and Confined Water, which had a non-exclusive focus on Ship Behaviour in Locks. For this conference, experimental model test data obtained at Flanders Hydraulics Research had been made public and researchers were encouraged to compare numerical with experimental results [1]. Data of benchmark tests carried out both with self-propelled and captive models were used by researchers for comparison with various numerical tools. The objective of this paper is to give a selected overview of how accurately numerical tools are presently able to predict the hydrodynamic forces that occur on ships approaching locks. Based on this, the paper concludes that experiments and numerical tools complement each other

Influence of the canal width and depth on the resistance of 750 DWT Perintis ship using CFD simulation

Investigation of hydrodynamic interaction between the vessel and the seabed when entering shallow water is considered one of the most critical considerations of inland waterway transport. There are many investigations into the behavior of ships in restricted waters, such as ships traveling in different forms of canal cross-sections. The present study aims to evaluate the hydrodynamic interaction of the 750 DWT Perintis Ship moving through the different canal types to determine the relative effects of limiting the width and depth cross section on the ship\u27s resistance. Two different canals with different cross sections, including canal bank and rectangular canal, were evaluated to investigate the influence of canal width (Wb), depth ratio (hw/T), and blockage ratio function (As/Ac). The Computational Fluid Dynamic (CFD) method with Reynolds-averaged Navier–Stokes (RANS) solver and turbulent model − were used to predict the total resistance of the ship. The proposed numerical simulation was initially validated with an experimental towing tank test in the error range of 0.11-7.74%. The results indicated similar phenomena were found both in rectangular and canal banks. The case with a shallower (lower hw/T) and a narrower (lower Bc/Bs) canal dimension has a higher resistance value. Backflow and subsidence of free surface became significant around the ship\u27s hull in more restricted water, changing the ship\u27s hydrodynamic characteristics and increasing resistance. It can be found that the higher the blockage ratio (mb), the higher the total resistance value in both canal types, which proved that ships with higher speeds were more sensitive to changes in waterway restrictions

CFD prediction and validation of ship-bank interaction in a canal

This paper utilizes CFD (Computational Fluid Dynamics) methods to investigate the bank effects on a tanker moving straight ahead at low speed in a canal characterized by surface piercing banks. For varying water depths and ship-to-bank distances, the sinkage and trim as well as the viscous hydrodynamic forces on the hull are predicted mainly by a steady state RANS (Reynolds Averaged Navier-Stokes) solver, in which the double model approximation is adopted to simulate the flat free surface. A potential flow method is also applied to evaluate the effect of the free surface and viscosity on the solutions. In addition, focus is placed on V&V (Verification and Validation) based on a grid convergence study and comparison with EFD (Experimental Fluid Dynamics) data, as well as the exploration of the modelling error in RANS computations to enable more accurate and reliable predictions of the bank effects

Numerical simulation of viscous flow around a tanker model

In this paper, numerical simulation of the viscous flow around a tanker model was carried out utilizing software package STAR-CCM+. A mathematical model based on Reynolds Averaged Navier-Stokes equations, k-ε turbulence model and Volume of Fluid method for describing the motion of two-phase media are given. Necessary boundary conditions for the mathematical model and the method of discretization are described as well. The influence of the grid density on the numerical results for the total resistance of tanker model was investigated using three different grid densities. Two different types of k-ε turbulence model are implemented and the deviations in numerical results are highlighted. Results for total resistance of tanker model, obtained by numerical simulations, were validated against experimental results. Experiments were performed in the towing tank of Brodarski Institut in Zagreb for wide range of Froude numbers. It has been shown that for all three grid densities and both types of k-ε turbulence model satisfactory agreement with experimental results can be achieved for whole range of Froude numbers. The scale effects are investigated by Computational Fluid Dynamics study for the same tanker model in three different scales. Numerically calculated scale effects on the wave resistance are reviewed