CFD Simulation Verification Processes at Planing Hulls using An Interceptor

Abstract

Experimental test is one of the methods for predicting drag ships using towing tank. This method has a good level of accuracy but requires quite complex equipment and costs. With the advancing technology of computing, the CFD method has emerged as an alternative for problem-solving, especially in hydrodynamics analysis. This study aims to ensure the accuracy of Computational Fluid dynamics (CFD) by verifying experimental data on high-speed vessel using an interceptor. The Interceptor system generates a hydrodynamic lift force by intercepting the flow of water under the hull. Comparison of experimental results and numerical simulations will involve analysis of drag, heave and trim. Numerical simulations were carried out using ITTC recommendations as testing standards. This research uses the grid independence study method to ensure the accuracy of the mesh. CFD simulations were carried out using the overset mesh method and the k-epsilon to solve turbulence flow. The Dynamic Fluid Body Interaction (DFBI) module is employed to resolve the dynamic motion of the ship in order to assess hull movements based on by fluid forces and moments. There can be two degrees of freedom in the heave and pitch directions. All simulations are performed in calm water condition. Verification is carried out by reviewing the condition of the ship without an interceptor and with an interceptor. 100% stroke and 60% interceptor were used as variations of the verification of this study. The results of this study indicate that the CFD analysis has been verified by the experimental method with a maximum error range of 10.7%. Planing hull is a type of fast ship that has quite complex hydrodynamic characteristics. This study also shows that the use of interceptors is proven to improve the performance of the planing hull ship.

Hydrodynamic Analysis of Integrated Interceptor-Stern Flap for Trim Control on High-Speed Planing Vessel

“…Some differences were also identified in the calculation errors due to difficulties in modeling an object in numerical computation based on the conditions used in experimenting with towing tanks. A similar trend has been reported by Hosseini et al [34] and Utomo et al [21] during the application of CFD calculations to planing ships, presenting an error of 4.63% to 9.97% in predicting ship resistance compared to the experimental results.…”

“…Several other experiments were conducted on high-speed vessels to measure resistance, trim, and center of gravity values at different interceptor speeds and heights. The results showed that the pressure under the transom increased in proportion to the size of the interceptor [20], [21]. Furthermore, Samuel et al studied the integration of the appendage in the Aragon 2 hull design and reported a 57% drag reduction in the close-to-chine position [22].…”

Analysis of deck house height and center of gravity in anti-capsize patrol boat

“…The results showed that the numerical method has the same phenomenon as the experiment: the ship has self-righting in all condition load cases. Numerical methods such as CFD have become famous for marine use, such as fast ship design [3,4] and ship performance [5,6]. Another CFD scheme such as mesh-free CFD, i.e., smoothed particle hydrodynamics (SPH) that is suitable for marine engineering cases such as water wave propagation [7,8] and sloshing in LNG cases [9][10][11].…”

Analysis of the double steps position effect on planing hull performances

“…To prevent this, the vessel can be equipped with devices that actively or proactively control the trim angle, or modifications can be made to the hull. Applying a trim control device on a high-speed craft, such as such as interceptor [49][50][51][52][53][54][55][56][57][58], trim tab [59][60][61], the combination of interceptor and trim tab [50,58] [41,45], and stern foil [62][63][64][65][66], can reduce drag and trim angle. Modifying the hull shape can also reduce the boat's drag, thus improving its performance, such as with a step hull [67] and tunneled hull [68], as examples.…”