CFD Analysis into the Drag Estimation of Smooth and Roughened Surface Due to Marine Biofouling

This study is to investigate drag on ship due to marine biofouling using CFD approach. A cargo ship with one year operation was used for the study and to examine the effect of biofouling between smooth and roughened hull by observing the result of CFD simulation. Simulation is done using CFD software based RANSE code together with SST based k-omega as turbulence setting and Grid Generator was used to build the hybrid grids. The result indicated that marine biofouling make significant increase for ship resistance up to 37 %. This fact is in good agreement with experimental test has been examined that fouling increases drag up to 80 % for two years

A multi-criteria decision analysis model for ship biofouling management in the Baltic Sea

Biofouling of ship hulls form a vector for the introduction of non-indigenous organisms worldwide. Through in-creasing friction, the organisms attached to ships' hulls increase the fuel consumption, leading to both higher fuel costs and air emissions. At the same time, ship biofouling management causes both ecological risks and monetary costs. All these aspects should be considered case-specifically in the search of sustainable management strate-gies. Applying Bayesian networks, we developed a multi-criteria decision analysis model to compare biofouling management strategies in the Baltic Sea, given the characteristics of a ship, its operating profile and operational environment, considering the comprehensive environmental impact and the monetary costs. The model is dem-onstrated for three scenarios (SC1-3) and sub-scenarios (A-C), comparing the alternative biofouling management strategies in relation to NIS (non-indigenous species) introduction risk, e co-toxicological risk due to biocidal coating, carbon dioxide emissions and costs related to fuel consumption, in-water cleaning and hull coating. The scenarios demonstrate that by the careful consideration of the hull fouling management strategy, both money and environment can be saved.Peer reviewe

Investigating the roughness effect of biofouling on propeller performance

As a result of the increasing pressure being placed on the marine industry to address ship emissions, regulations to govern the fuel efficiency and efficient operation of ships in the form of the Energy Efficiency Design Index (EEDI) (IMO, 2014) and Energy Efficiency Operation Index (EEOI) (IMO, 2009a) have recently come into force. These have been introduced alongside regulations concerning specific emissions requirements (UNFCCC). Attention has therefore been turned to all aspects of ship design and operation which have impact on their efficiency. In turn, this paper focuses on the effects of biofouling on propeller surfaces highlighting the benefits of reducing biofouling. This subject was the focus of a recently completed EU-Funded FP7 Project entitled FOUL-X-SPEL (2011). This paper investigates the detrimental impacts of biofouling on the performance of a real ship propeller using Computational Fluid Dynamics (CFD) simulations. Initially, the CFD approach used in this study was validated through CFD open-water tests of a propeller. A previously-developed CFD approach for approximating the surface roughness that results from biofouling has then been applied in order to predict the effects on propeller efficiency. The roughness effects of a typical coating and different fouling conditions on the propeller performance were therefore predicted for various advance coefficients Results indicated negative effects of biofouling on the propeller efficiency and the importance of the mitigation of such effects, supporting the importance of informing the industry about the impacts such that they are able to make informed decisions regarding regular propeller maintenance and cleanin

Toward a Global Regime of Vessel Anti-Fouling

Vessel anti-fouling is key to the efficient operation of ships, and essential for effective control of invasive species introduced through international shipping. Anti-Fouling Systems, however, pose their own threats to marine environments. The Anti-Fouling Convention of 2001 banned the use of organotin compounds such as Tributyltin, and created a system for adoption of alternative anti-fouling biocides. In 2011, the Marine Environmental Protection Committee of the International Maritime Organization (IMO) released guidelines on bio-fouling management record keeping, installation, inspection, cleaning, maintenance, design and construction. Though these Guidelines provide a template for more effective and environmentally sound anti-fouling control and implementation, they are not mandatory. This article proposes that the member states of the IMO adopt the 2011 Guidelines as a mandatory instrument

On the importance of antifouling coatings regarding ship resistance and powering

This paper aims to introduce one of the latest investigations on development of marine antifouling coatings and also to demonstrate the importance of the type of antifouling coatings on fouling accumulation and ship resistance/powering. First, marine biofouling and fouling prevention methods are reviewed. A recent research study (EU FP7 FOUL-X-SPEL Project) concerning a novel and environmentally friendly antifouling coating is presented and discussed. Next, a case study is carried out to assess the effect of fouling on ship resistance and powering. A vessel is selected and the roughness on the hull surface induced by different level of fouling is considered. The increase in frictional resistance and effective power is evaluated for each particular case by using boundary layer similarity law analysis and experimental data. The results emphasise that the type of antifouling coatings has a great importance on the amount of fouling accumulation, hence on ship performance especially in low speed

Penalty of hull and propeller fouling on ship self-propulsion performance

Recently, there has been an increasing interest in predicting the effect of biofouling on ship resistance using Computational Fluid Dynamics (CFD). For a better understanding of the impact of biofouling on the fuel consumption and green-house gas emissions of ships, studying the effect of biofouling on ship self-propulsion characteristics is required. In this study, an Unsteady Reynolds Averaged Navier–Stokes (URANS) based full-scale ship self-propulsion model was developed to predict the effect of biofouling on the self-propulsion characteristics of the full-scale KRISO container ship (KCS). A roughness function model was employed in the wall-function of the CFD model to represent the barnacles on the hull, rudder and propeller surfaces. A proportional-integral (PI) controller was embedded in the simulation model to find the self-propulsion point. Simulations were conducted in various configurations of the hull and/or propeller fouling. Finally, the effect of biofouling on the self-propulsion characteristics have been investigated

Life cycle assessment of an antifouling coating based on time-dependent biofouling model

This paper presents a novel life cycle assessment (LCA) for antifouling coatings based on a time-dependent biofouling prediction model. The life cycle assessment covers environmental and monetary effects born from paint production to application, hull maintenance and added fuel consumption due to biofouling on the ship hull. The calculations related to the production and applications of the paints were made using the data provided by shipyards and coating manufacturers.The added frictional resistance due to biofouling accumulation and hence the added fuel consumptions during ship operations were predicted by time-dependent biofouling model proposed in the literature and then implemented into the overall life cycle assessment. The effects of ship operating profile and route on the fuel penalty due to biofouling accumulation on the antifouling coating were investigated for three case studies. The results were presented in terms of differences in increases in effective power, fuel oil consumption, fuel oil consumption costs, total costs and CO2 emissions due to different ship operating profiles and routes

DEVELOPMENT OF MODEL-DRIVEN DECISION SUPPORT SYSTEM TO SCHEDULE UNDERWATER HULL CLEANING

Maritime industries are constantly searching for a method to enhance ship efficiency, with increasing concern about the environmental impact and rising fuel prices. Marine biofouling is one of the factors that increase ship fuel consumption. However, removing the fouling of the ship requires effort for hull maintenance. Due to the trade-off between conducting maintenance and performance degradation, this study presents the development of a Model-Driven Decision Support System (MD-DSS) to predict the optimum time for underwater hull cleaning for biofouling management. Five stages (sub-models) are employed to develop a DSS, namely: ship resistance estimation, estimation of additional resistance due to biofouling, an iterative-based method for determining the best time to conduct the hull cleaning, and an analysis report. The implemented algorithm was validated by comparing its result with a manually scheduled maintenance date. The DSS is able to determine the best time (date) for maintenance in all given scenarios. By giving two scenarios of different maintenance costs and different fuel prices, the optimisation results produce the same number of maintenances. Within 60 months, four to five hull cleanings are required. It is also found that when the optimal number of maintenances is known, then increasing this number will not have any impact on reducing the hull cleaning costs because the reduction in fouling does not significantly reduce the costs incurred for maintenance. During several trials of the DSS, it is shown that the system can generate maintenance schedules for different time intervals of ship operation within an acceptable time. It takes approximately 52 minutes, 12 minutes, and 5 minutes consecutively to determine the maintenance schedules for ship operation intervals of 5 years, 2.5 years, and 1 year

Predicting the effects of fouling control coatings and heterogeneous hull roughness on ship resistance

This research builds on one of the spotlights of fluid-hull interaction theories: the effects of hull surface conditions on ship hydrodynamics. Several factors, such as biofouling accumulation, coatings failure, and corrosion, deteriorate the hull surfaces (i.e., increasing the hull roughness). Although the consequences of poor hull surface conditions on fuel consumption and emissions are well-known, the rationales behind the hull roughness effects on ship performance are yet to be thoroughly understood. Furthermore, there is epistemic uncertainty associated with biofouling management strategies (e.g., the choice of fouling control coatings and drydocking operations). Last but not least, although hull roughness is typically spatially heterogeneous, most research has only dealt with homogeneously distributed hull roughness. Therefore, given the importance of hull roughness on ship performance from economic and environmental perspectives, this thesis aims to investigate the effects of fouling control coatings, mimicked biofouling and heterogeneous hull roughness on ship hydrodynamics using experimental and numerical methods. Part I (Chapters 4 and 5) of the thesis presents experimental roughness function data for different surfaces, including a hard foul-release coating developed from the fully turbulent flow channel (FTFC) facility of the University of Strathclyde. Furthermore, the results of the FTFC tests were compared against flat plate towing tank tests showing excellent agreement. Afterwards, Part II (Chapter 6 and 7) employed the experimental results in similarity law scaling and Computational Fluid Dynamics (CFD) analysis for full-scale predictions at different speeds. Notably, more than one of the paints tested showed a reduction in the estimated effective power requirements (i.e., up to 5.7%). Finally, Part III (Chapter 8) extended the CFD analysis to the effects of the heterogeneous distribution of hull roughness on ship resistance by simulating heterogeneous scenarios with various hull forms, and speeds. Eventually, the results were correlated by defining a Roughness Impact Factor (RIF) which could have practical implications for biofouling management decisions.This research builds on one of the spotlights of fluid-hull interaction theories: the effects of hull surface conditions on ship hydrodynamics. Several factors, such as biofouling accumulation, coatings failure, and corrosion, deteriorate the hull surfaces (i.e., increasing the hull roughness). Although the consequences of poor hull surface conditions on fuel consumption and emissions are well-known, the rationales behind the hull roughness effects on ship performance are yet to be thoroughly understood. Furthermore, there is epistemic uncertainty associated with biofouling management strategies (e.g., the choice of fouling control coatings and drydocking operations). Last but not least, although hull roughness is typically spatially heterogeneous, most research has only dealt with homogeneously distributed hull roughness. Therefore, given the importance of hull roughness on ship performance from economic and environmental perspectives, this thesis aims to investigate the effects of fouling control coatings, mimicked biofouling and heterogeneous hull roughness on ship hydrodynamics using experimental and numerical methods. Part I (Chapters 4 and 5) of the thesis presents experimental roughness function data for different surfaces, including a hard foul-release coating developed from the fully turbulent flow channel (FTFC) facility of the University of Strathclyde. Furthermore, the results of the FTFC tests were compared against flat plate towing tank tests showing excellent agreement. Afterwards, Part II (Chapter 6 and 7) employed the experimental results in similarity law scaling and Computational Fluid Dynamics (CFD) analysis for full-scale predictions at different speeds. Notably, more than one of the paints tested showed a reduction in the estimated effective power requirements (i.e., up to 5.7%). Finally, Part III (Chapter 8) extended the CFD analysis to the effects of the heterogeneous distribution of hull roughness on ship resistance by simulating heterogeneous scenarios with various hull forms, and speeds. Eventually, the results were correlated by defining a Roughness Impact Factor (RIF) which could have practical implications for biofouling management decisions