VERTICAL AND SLOPED BANK EFFECTS ON DIFFERENT SHIP TYPES

The Author describes how the bank effects that occur when a ship sails in confined waters can be studied with a numerical method. Being involved in the Knowledge Centre “Manoeuvring in Shallow & Confined Water” (Ghent University & Flanders Hydraulics Research, Antwerp, Belgium), we have read the paper with interest.

VERTICAL AND SLOPED BANK EFFECTS ON DIFFERENT SHIP TYPES

This study employed computer design software to completely draft 3D ship models; then, computational fluid dynamics were used to establish numeric navigation channels and simulate fluid hydrodynamic analysis of ships navigating along shore banks. The parameters considered comprised bank type (vertical and sloped), ship model (two types), velocity, ship-to-bank distance, and navigation time. Figures and tables were used to present the distribution of ship stern eddy current, flow field pressure, and velocity, and the comparison of center of mass deviation, sway force, and yaw moment. Results showed that ships navigating along embankments and channels produced asymmetric flows, which draw the bow away from the shore. Larger ships are substantially more influenced by bank effects than smaller ships. Large sway forces and yaw moments are produced in large ships, drifting the bow away from the bank and the stern towards the bank, increasing the risk of collision with the embankment. From the study results, the characteristics of bank effects are understood and can be used for assisting the safe navigation of ships in restricted waters.

REVIEW OF PRACTICAL ASPECTS OF SHALLOW WATER AND BANK EFFECTS

The ship’s behaviour and manoeuvrability change as depth of water decreases and/or when the ship is near a bank or shoal. This paper conducts a review on shallow water effects (SWE) and bank effects (BE). It summarizes the varying opinions from both experienced mariners and hydrodynamicists about SWE on factors such as resistance, trim, steering, manoeuvrability and stopping, as well as BE on elements such as bank suction and cushion and it is shown that there is not a common sense in the bibliography. This is strange because the successful navigation of a ship along the channel to the dock is an identifiable task whose outcome is the same in all cases. Yet surprisingly it is a subject upon which there are different opinions documented. This review refreshes mariner’s memory and raises controversial topics that need clarification for the benefit of mariners, simulator modellers and the maritime industry they work.

HYDRODYNAMIC INTERACTION BETWEEN SHIPS AND RESTRICTED WATERWAYS

In open and unrestricted waters the water displaced by a forward sailing vessel can travel without major obstruction underneath and along the ship. In restricted and shallow sailing conditions, the displaced water is squeezed between the hull and the bottom and/or the bank. This results in higher flow velocities and as a consequence a pressure drop around the same hull. In the vicinity of a bank this pressure drop generates a combination of forces and moments on the vessel, known as bank effects. The major achievement of the presented research is the development of a realistic and robust formulation for these bank effects. This knowledge is acquired with an extensive literature study on one hand and with dedicated model tests carried out in different towing tanks on the other. The majority of the utilised model tests were carried out in the shallow water towing tank at Flanders Hydraulics Research in Antwerp, Belgium. The data set on bank effects consists of more than 8 000 unique model test setups (which is by far the most elaborate research ever carried out on this subject). These model tests provide the input for the analysis of bank effects and the creation of the mathematical model.

Installing Islamic banking windows in conventional bank: Effects on performance

Islamic finance products have become very common in financial transactions, and thus offer new business opportunities. The objective of our study was to investigate the effect of distributing Islamic banking products on the financial performance of commercial banks, over a period of seven years (2010–2017). We use a Correlation analysis to carry out the strength of the relationship between our dependent variable: bank performance variable: return on assets, and independent variables which are Islamic products. Studying the variables collected, we found evidence that there was a significant positive relationship between bank performance: return on asset and Murabaha, Mudaraba, although Ijara had a positive relationship with return on assets but not significant. We notice that all the available Islamic products in commercial banks used, had a positive significant relation with the exclusion of Ijara which had positive insignificant relationship. This implies that an increase in using Islamic banking products in commercial banks will lead to increase in conventional Banks performance.

The Influence of the Ship's Speed and Distance to an Arbitrarily Shaped Bank on Bank Effects

In shallow and restricted waterways, the water displaced by a sailing ship is squeezed under and along its hull. These confinements result in increased velocities of the return flow along the hull and the induced pressure distribution on the hull causes a combination of forces and moments on the vessel. If generated because of asymmetric flow due to the presence of a bank, this combination of forces and moment is known as bank effects. A comprehensive experimental research program on bank effects has been carried out in the towing tank for maneuvers in shallow water (cooperation Flanders Hydraulics Research—Ghent University) at Flanders Hydraulics Research (FHR) in Antwerp, Belgium. The obtained data consist of more than 14,000 unique model test conditions. The relative position and distance between a ship and an arbitrarily shaped bank is ambiguous. Therefore, a definition for a dimensionless distance to the bank is introduced. In this way, the properties of a random cross section are taken into account without exaggerating the bathymetry at a distance far away from the ship or without underestimating the bank shape at close proximity to the ship. Also, a dimensionless velocity is introduced to take the influence of the water depth, forward speed, and blockage into account. The proposed mathematical model for bank effects, often described as a sway force and yaw moment, is instead decomposed in two sway forces at each perpendicular.