Comparative fluid behavior simulation to understand key factor underlying the efficiency of two different ships.
Flow around ship hull has always been a subject of great concern both for naval architects and shipyards in order to ensure that a ship can operate efficiently and economically at a desired speed. In past years, the computational power and run-time required by Computational Fluid Dynamics (CFD) codes restricted their use in ship design space exploration. Increases in computational power available to designers, in addition to more efficient codes, have made CFD a valuable tool for early stage ship design and trade studies. To analyze the flow physics and validate computed results, two cases of simulations are carried out with Korean KRISO Container Ship (KCS) and Bangladeshi MV Yousuf Arafat (YA). In this work these existing physical model were replicated in STAR-CCM+. Towed resistance was calculated at various speeds. The bare hull model was unconstrained in heave and pitch, thus allowing the simulation to achieve steady dynamic attitude for each speed run. The effect of dynamic attitude on the resistance is considered to be significant and requires accurate prediction. The results were validated by comparison to available data from tow tank tests of the physical mode and resistance calculated from MAXSURF module. The results demonstrate the accuracy of the CFD package and the potential for increasing the use of CFD as an effective tool in design space exploration. This will significantly reduce the time and cost of studies that previously depended solely on physical model testing during preliminary ship design efforts.
In brief we can notate our motivation likewise below:
- It is required to predict the power required to design efficient ship to optimize economically and environmentally
- The power required is directly controlled by the resistance ship is facing in seaways
- In order to determine resistance accurately, the features of the flow around the ship hull must be measured accurately in a way that designers can try many hulls without spending too much time, effort and resources.
- Testing a ship model in towing tank is relatively costly and time consuming
- Simulating a ship in a virtual towing tank using computational resources is far more less time consuming and less costly too.
- Testing the accuracy achieved will influence our confidence over computer simulation positively
- Comprehensive data can be extracted from CFD, whereas a physical test case can only provide data from a limited number of locations. In addition, there is no testing apparatus interacting with the flow in case of CFD simulation.
- Greater control over the set-up of the experiment. Conditions which would be difficult or impossible to achieve in a towing tank can be easily created in numerical tank
The benefits of CFD compared to traditional model tests are many, with the major ones being listed below:
- Simulation cost is relatively low compared to physical experiments.
- CFD simulations can be carried out faster than physical experiments. In addition, changes to the original design can be made quickly.
- Comprehensive data can be extracted from CFD, whereas a physical test case can only provide data from a limited number of locations. In addition, there is no testing apparatus interacting with the flow.
- Greater control of the set-up of the experiment. Conditions which would be difficult or impossible to achieve in a towing tank can be easily created in numerical tank.
