CHAPTER ONE

1.0 INTRODICTION

1.1 BACKGROUND OF STUDY

Prediction of ropax vessel’s maneuverability characteristics and resistance is essential at early phase of ropax vessel design to understand its design efficiency. Although, model tests are most popular for such predictions, in recent years, Computational Fluid Dynamics (CFD) has gained high popularity for such predictions because of its high efficiency and economics. CFD is very efficient because it allows exploration of new engineering design frontiers in an economical way. Furthermore, over the years, the accuracy of CFD prediction has improved significantly. Thus, more and more research is being done on how to predict the stability and maneuvering capabilities of a ropax vessel in the design phase using CFD. Maneuverability prediction in the design phase is nothing new for the ropax vesselping industries. According to reports of 20th− 24th ITTC by Larson, (2011), the first symposium on Naval Maneuverability was held in Washington DC in 1960. However, back then work was mostly experiment based.

Numerical prediction for maneuverability using the boundary layer method was first introduced in 1980. However, it failed to predict pressure in the stern part properly. This had led to the development of various RaNS models throughout the 1980s. In 1990, it was found that RaNS models showed high promise but failed to predict detail shape of velocity contours in central part of wake. Later in 1993, Deng et al. revealed that the problem was in inadequate turbulence modeling. The 1994 Tokyo workshop brought a breakthrough in free surface calculation using RaNS. For The Gothenburg 2000 workshop, three new ropax vessel models- KCS, KVLCC and DTMB 5415 were introduced with experimental results for validation. The self-propulsion system included CFD models were also introduced in this workshop. In The SIMMAN 2008 workshop, benchmarking was conducted for both EFD based and CFD based methods. The Gothenburg 2010 workshop discussed global and local flow variables, grid dependency, and turbulence modeling. Since then, several research groups have developed numerous in-house codes and also several commercial codes have been developed for ropax vessel simulations.

1.2 STATEMENT OF PROBLEM

Over the years, CFD in maneuverability prediction has gone through and is still going through continuous improvement. However, with increase in prediction accuracy, computational time has increased as well, despite the fact that, computing capacity has increased significantly over the years. This is mainly because of our tendency to simulate exact real life conditions. The requirement of high computational resources has driven us to high performance computers and reduced the economy of CFD. Besides, licenses for commercial CFD codes are also expensive, which limits their popularity among research groups

1.3 AIM AND OBJECTIVES OF STUDY

The main aim of the research work is to examine calm water resistance of ropax vessel using Reynolds average navier stroke base solver. Other specific objectives of the study are:

1. to determine the maneuverability of the ropax vessel in water
2. to predict ropax vessel’s resistance and motion characteristics with high accuracy utilizing minimum computational resources
3. to investigate on the factors affecting the ropax vessel maneuverability in water
4. to determine the computational time accuracy of the Reynold’s average navier stroke base solver
5. to proffer solution to the above problem

1.4 RESEARCH QUESTIONS

The study came up with research questions so as to ascertain the above the above objectives. The research questions for the study are:

1. What is the maneuverability of the ropax vessel in water?
2. What are the ropax vessel’s resistance and motion characteristics with high accuracy utilizing minimum computational resources?
3. What are the factors affecting the ropax vessel maneuverability in water?
4. What is the computational time accuracy of the Reynold’s average navier stroke base solver?

1.5 ORGANISATION OF STUDY

This section deals with the organization of the research work in chapters; the chapter one of the research work will cover the background of the study, the statement of problem, the aims and objectives of study, significance and the scope of study, the chapter two will deal with the review of related literature on calm water resistance of ropax vessel using Reynolds average navier stroke base solver. The chapter three of the research work will cover the areas of the computational method. The chapter four will cover the area of experiment; while the chapter five will cover the summary, conclusion and possible recommendation for the research work

1.6 SIGNIFICANCE OF STUDY

The study on calm water resistance of ropax vessel using Reynolds average navier stroke base solver will be of immense benefit to the marine engineering department in the sense that the study will educate the students and other researchers on how to use the Reynolds average navier stroke base solver, to also determine the ropax vessel’s resistance and motion characteristics with high accuracy utilizing minimum computational resources. The study will serve as a repository of information for other researchers that desire to carry out a similar research on the above topic. Finally the study will contribute to the body of existing literature and knowledge in this field of study and provide a basis for further research

1.7 SCOPE OF STUDY

The study will focus on the calm water resistance of ropax vessel using Reynolds average navier stroke base solver. The study will cover on how to use the Reynolds average navier stroke base solver to determine calm water resistance of ropax vessle, to also determine the factors affecting the ropax vessel maneuverability in water.

1.8 LIMITATION OF STUDY

Financial constraint- Insufficient fund tends to impede the efficiency of the researcher in sourcing for the relevant materials, literature or information and in the process of data collection (internet).

Time constraint- The researcher will simultaneously engage in this study with other academic work. This consequently will cut down on the time devoted for the research work

1.9 DEFINITION OF TERMS

Ropax vessel:  is an acronym for roll on/roll off passenger. It is a ro-ro vessel built for freight vehicle transport with passenger accommodation. The vessels with facilities for more than 500 passengers are often referred to as cruise ferries

Viscosity: The viscosity of a fluid is the measure of its resistance to gradual deformation by shear stress or tensile stress.

Resistance: the refusal of water to accept the ropax vessel or comply with its maneuverability.