Benchmark Study of FINETM/Marine CFD Code for the Calculation of Ship Resistance

Benchmarking can be used to test CFD programs for selecting turbulence models, grid dependency studies, testing different numerical schemes and source codes, and testing different boundary conditions. CFD simulation in this study uses FINE™/Marine 7.2-1 software. The solver process at NUMECA uses the ISIS-CFD flow solver developed by EMN, which uses the incompressible unsteady Reynolds-average Navier stoke equation (RANSE). The solver is based on the finite volume method, and Turbulence models use SST k-ω models. The free surface flow around a model surface ship (DTMB 5415) advancing in calm water under steady conditions is numerically simulated. The geometry of the DTMB 5415 ship hull was provided in igs file format. The 1996 International Towing Tank Conference has recommended the DTMB 5415 combatant as a benchmark case for CFD computations of ship resistance and propulsion. The results compare well with the available experimental data. They allow an understanding of the differences that can be expected from vicious and potential flow methods due to their different mathematical formulations. It is demonstrated that the complementary application of these methods allows good predictions of the total ship resistance.

The Strength and Fatigue Life analysis of Sedan Car Ramp of The Ferry Ro-Ro 5000 GT Using Finite Element Method

The Ferry Ro-Ro 5000GT has three levels of car deck that are connected by internal ramps. Two issues that have to be paid attention during the operation of the internal ramp there are the strength capacity and the design fatigue life of the internal ramp structure. The purpose of the research is to determine the strength and fatigue life of the internal ramp construction. The method used the Finite Element Method using a static load by load case of point load at top girder and between girders. Results of the research detected the maximum stress value is in the load case of the point load (three sedan car) at between of the girder is 52.143 MPa with the fatigue life is 44.47 years with the load cycle is 7300000 cycle while the minimum stress value detected at the load case of the point load (two sedan cars) at top girder is 34.199 MPa with the fatigue life is 195.92 years with the load cycle is 50000000 cycle. For the safety factor, ramp construction 6.08 ~ 10.38. The safety factor value above is still in safe condition because the value is SF > 1.

Roll Motion Analysis on Unmanned Surface Vehicle with Remote Controlled Weapon Station Models to Combat Piracy in Surabaya West Access Channel

The dense shipping activity in the Surabaya West Access Channel (SWAC) is accompanied by a high rate of piracy which had 13 cases during 2013–2018. An Unmanned Surface Vehicle (USV) with Remote Controlled Weapon Station (RCWS) was created to overcome this piracy, increase work effectiveness, and reduce potential casualties. This study aims to create a design of USV equipped with RCWS complies with the requirements then analyzes the stability and seakeeping (roll motion) because it is one of the most determining factors of the stability and safety of the ship. The research method in this study is a simulation process based on system engineering theory starting from the formulation of requirements, design making, and then simulation. Five design models are created and simulated to analyze their stability and seakeeping performance. The design results are a monohull USV equipped with an RCWS with the main dimension of 1.7 m long, 0.9 m wide, and 1.04 m high. The stability simulations conclude that Model 4 is the most stable platform with the highest peak value of GZ for 0.112 m in angle degree of 108.2°. The seakeeping simulations show that at wave heading 45°, model 3 has the highest RAO with the peak value of 4.703 at the frequency of 0.4 rad/s. At wave heading 90°, model 5 has the highest RAO with the peak value of 0.095 at the frequency of 0.4 rad/s. At wave heading 135°, model 1 has the highest RAO of 0.012 at the frequency of 0.581 rad/s.

Real-Time Fuel Consumption Monitoring System Integrated With Internet Of Things (IOT)

Fuel is an important aspect in the operation of ships that require high costs. The high cost of fuel is not followed by an automatic fuel monitoring process. By not using the fuel consumption monitoring method that works automatically, the shipping management does not know for sure the ship's fuel consumption is in accordance with the shipping mileage, thus triggering fraud committed by the ship's crew against the ship's fuel. Fuel consumption monitoring is carried out primarily to identify opportunities to improve energy efficiency and reduce costs. By following technological developments, Internet of Things (IoT) technology has begun to be applied in various industrial fields because it can transmit data in real-time via the internet network without human-to-human or human-to-computer interaction. In this research, the design of models and experiments related to a monitoring system for fuel consumption was carried out using sensors and microcontrollers integrated with the internet to obtain accurate and real-time data. The test results show that the volume of fuel available in the tank, the volume of fuel discharged, the flow rate of fuel, and the location of the system can be known by the user in real-time via the IoT website. Based on the results of measurements using an ultrasonic level sensor, it is known that the measurement results are quite accurate with a deviation of ± 0.5 cm. Meanwhile, the measurement results by the flow sensor are less accurate because the fuel flow only relies on the force of gravity.

The Effect of Trim on Tanker, Container and Bulk Carrier Ship Toward the Reduction of Ship’s Exhaust Gas Emission

Emission is one of the few environmental problems, and ships are one of the modes of transportation that produce it. This study aims to define the impact of using optimal trim during the cruising phase, so it can decrease the resistance and the fuel consumption, which will lead to less emission produced by the ship. The type and amount of ships used in this study are three tanker ships, three container ships, and two bulk carrier ships. The methodology used in this study is by using Holtrop’s resistance calculation method with the help of Maxsurf software. The resistance, the power needed, and the fuel consumption is calculated on 22 trim variations and seven speed variations. This study determined that the average decrease in fuel consumption caused by trim optimization for tanker, container, and bulk carrier ships is 5.641%, 8.269%, and 15.704%. Furthermore, the average decrease of emissions produced by tanker, container, and bulk carrier is 6.494%, 11.317%, and 13.775%, respectively. These results are narrowed down to conclude that trim optimization can reduce fuel consumption by up to 9.871% and decrease the emission produced by up to 10.529% for the three types of ships used in this study.

The TLP 2-DOF as an alternative model for extreme wave application

Tension Leg Platform (TLP) is an offshore platform structure used for deep-sea oil and gas exploration. The main structure of the TLP consists of a deck, pontoon, mooring system, and foundation. TLP operates in a balance of buoyancy, structural weight, and mooring tension. The problem is the construction of TLP in the deep sea, where sometimes extreme waves appear could damage the TLP structure. This paper proposes a new model of TLP that is more stable to extreme waves. The method is to separate the mass of the deck and the mass of the pontoon into two flexible parts, which are connected by a cantilever spring system. Thus the TLP motion becomes two degrees of freedom (TLP 2-DOF). Using the dynamic vibration absorber (DVA) method, the ratio of the deck mass, pontoon mass, and spring stiffness are adjusted so that the primary mass movement is minimal. Furthermore, the ratio of the amplitude of the deck movement as the primary mass to the wave amplitude is analyzed, which is known as the operator response amplitude (RAO). The results showed that the TLP 2-DOF model was more stable. As an illustration, at resonance conditions, this model can reduce RAO to about 67%.

Experimental Investigation of Bow Slamming on a Ship: The Effect of Weight and Impact Angle

The impact pressure induced by slamming can imply physical damage on a ship. The high probability of the slamming impact is on the bow part in the actual sea state. In this present study, the slamming induced pressure on the bow flare of a ship have been investigated through the experiment. The experiment was schemed by the dropping test based on free-falling body in the wave tank, wherein the bow of the ship model was inclined in several impact angles 0° to 30° to the free-water surface. To measure slamming impact pressure acting on the bow flare, the piezoelectric sensors S1, S2, S3, S4 were attached to the bow section and installed on a computer. As the obtained results, the impact pressure on bow flare occurred in a short time duration caused by slamming. The discrepancy of the peak impact pressure between ship model weight of 2.42 kg and 7.29 kg for the impact angle 0° is 70.36% S1, 69.52% S2, 68.97% S3, and 68.34% S4. For the relative impact angle of 30°, the discrepancy is 67.02% S1, 65.73% S2, 58.51% S3, and 48.21% S4. The tendency of the peak pressure coefficient at the sequenced impact points S1, S2, S3, S4 is similar for all impact angles 0°, 10°, 20°, and 30°. The peak pressure coefficient due to the full load condition is highest in the nearest bottom part, and the peak pressure coefficients due to the lightship condition highest in the nearest bottom part caused by the small impact angle.

Transmission Coefficient Analysis of Notched Shape Floating Breakwater Using Volume of Fluid Method: A Numerical Study

As one of the coastal structures, breakwaters are built to protect the coastal area against waves. The current application of breakwaters is usually conventional breakwaters, such as the rubble mound type. Climate change, which causes tidal variations, sea level height, and unsuitable soil conditions that cause large structural loads, can be solved more economically by employing floating breakwater. In this study, numerical simulations will be conducted by exploring the optimum floating breakwater notched shapes from the Christensen experiment. The comparison of three proposed floating breakwater models, such as square notch (SQ), circular notch (CN), and triangular notch (VN), is compared with standard pontoon (RG) to optimize the transmission coefficient value is analyzed. Numerical simulations are conducted using Computational Fluid Dynamics (CFD) based on the VOF method with Flow 3D Software. Compared to the experimental study, the RG model's validation shows a good result with an error rate of 8.5%. The comparative results of the floating breakwater models are found that the smaller the transmission coefficient value, the more optimal the model. The SQ structure has the smallest transmission coefficient of 0.6248. It can be summarized that the SQ model is the most optimal floating breakwater structure.

Strength Analysis and Repair Strategy of Aged Steel Jetty Pile

Indonesia has 95.161 km coastal lines with a total of 17.504 islands. With this nature, Indonesia has 1.226 ports, with a total accumulated length of up to 92 km. However, not all these ports are in proper condition. For ports that have steel jetty piles, corrosion is one of the problems. This paper provides technical experience and methodology for analyzing the pier's corrosion conditions and evaluating existing corrosion's effect on its strength. The survey methodology and required data, including a survey of cathodic protection, visual conditions, and pile thickness, are discussed in this paper. The static strength analysis of the existing state structure was carried out. This article provides repair strategies, including repair methods and a study of the number of piles repaired. This methodology results in the recommendations for pile repair strategies and guidance on effective analytical methods in determining the number of repaired piles for aged steel jetty pile repair.

Comparative Analysis of Taper and Taperless Blade Design for Ocean Wind Turbines in Ciheras Coastline, West Java

The blade is the most critical part of turbine design because it is used to convert kinetic to mechanical energy. In general, the blade types used for ocean wind turbines are taper and taperless blades, like those operated at Ciheras Coastline. Previous research has been analyzed the type of airfoil used in designing taper blades for ocean wind turbines using NACA 4412, which was selected as the optimal foil configuration at sea wind speeds of 12 m/s. In this study, the comparison of taper and taperless blade designs using NACA 4412 at a wind speed of 12 m/s is analyzed. The comparative study with previous research has been carried out and resulted in the same graphical patterns and performance results. In this study, the focus is on investigating the performance coefficient of power, mechanical power, and electrical power. The final result shows that taper blade designs are highly recommended for use in ocean wind turbines compared to taperless blades. In general, the performance produced by taper blades is more significant than taperless blades at relatively high wind speeds. The maximum performance coefficient of power, mechanical power, and electrical power generated by the taper blades in sequent are 0.47, 1535 watts, and 786 watts, while the taperless blades have 0.44, 1437 watts, and 736 watts.