Numerical ventilation problem (NPV) is a problem that often occurs during the numerical simulations process. This problem mostly occurs when the vessel has a high Froude Number, causing inaccurate ship resistance predictions. Numerical ventilation can be considered as one of the major sources of error in numerical simulations that require further analysis. The present paper aims to validate a numerical resistance prediction using Fridsma’s hull form. An overset grid system is implemented in this study to solve using the Volume of Fluid method. The method for improving the accuracy of ship resistance prediction are refinement method, visualization method, and phase replacement method. In this paper, the RANS equation is used to describe the turbulence model using k-ε. On most occasions, the Volume of Fluid model uses multiphase Euler flow, assuming air and water as a phase. This research concludes that mesh refinement method is able to solve numerical ventilation problem with such a good result.

ABSTRAKPrediksi hambatan kapal tipe planing lebih rumit dibanding dengan tipe displacement, hal ini disebabkan oleh gaya hidrodinamis yang lebih dominan pada bagian bawah kapal. Karakteristik hambatan kapal tipe planing sangat dipengaruhi oleh gerakan trim dan heave. Selain itu, bentuk hullform juga mempengaruhi hambatan kapal; seperti sudut dead-rise, chine, strip, stephull, dan lain-lain. Solusi untuk memprediksi hambatan kapal dengan menggunakan Finite Volume Method (FVM). Persamaan RANS (Reynolds- Averaged Navier-Stokes) dengan model turbulensi k-ε untuk memprediksi aliran turbulen dan Volume of Fluid (VOF) untuk mempresentasikan aliran 2 fasa. Pada penelitian ini digunakan metode overset mesh untuk memprediksi hambatan kapal agar mendapatkan akurasi yang baik. Hasil simulasi hambatan menunjukkan trend yang baik. Pada kecepatan tinggi, prediksi hambatan tidak memiliki hasil yang baik. Solusi yang ditawarkan pada Numerical ventilation problem (NVP) adalah dengan menggunakan metode phase replacement.Kata kunci: CFD, planing hull, RANS, overset mesh, NVP ABSTRACTThe prediction of planing hull resistance is more complicated than the displacement hull. It is caused by the more dominant hydrodynamic force at the bottom of the ship. The planing hull resistance characteristics are strongly influenced by trim and heave movements. In addition, the shape of the hullform also affects the ship's resistance, such as dead-rise angle, chine, strip, stephull, and others. The solution to predict ship resistance is by using the Finite Volume Method (FVM). RANS (Reynolds-Averaged Navier-Stokes) equation k-ε turbulence model was used to predict turbulent flow and Volume of Fluid (VOF) to present 2 phase flow. In this study, the overset mesh method was used to predict ship resistance in order to get good accuracy. Resistance simulation results showed a good trend. At high speeds, the prediction of resistance did not have good results. The solution offered in the Numerical ventilation problem (NVP) was to use the phase replacement method.Keywords: CFD, planing hull, RANS, overset mesh, NVP

A high-speed vessel has a range of Froude Number (Fr) > 1. A drag prediction method based on Fr > 1 has high complexity because it is influenced by trim and heave motions. Hence, a specific treatment is necessary to obtain accurate results. This study is using mesh density and mesh shapes to predict the total drag of a planing hull ship. The Computational Fluid Dynamic (CFD) results show good performance in predicting the drag, trim, and heave. Mesh density of 2300K shows the most stabilized result. The trimmed mesh type is more efficient to obtain accurate results because it has a smaller mesh size. The polyhedral mesh type is as good as trimmed mesh but is not as efficient as trimmed mesh and it has largely a time-consuming time.

The acting on the planing hull is the most complex hydrodynamics simulation. Therefore, an analysis was done to evaluate drag, lift force, and seakeeping in two degrees of freedom (2-DOF) which is heave and trim. It was fundamental aspects of the overall high-speed vessel. This article focused on the hydrodynamic performance of a complete interceptor configuration that could control the motion behavior of deep-V planing hull in calm water conditions. The benchmark study was undertaken by comparing numerical results with experimental study by Park at al. Models with and without interceptors had been analyzed by numerical simulation performed using Reynold Averaged Navier Stokes (RANS) to describe turbulence model with k epsilon based on computational fluid dynamic (CFD). In this study, the interceptor proper applies at a speed of less than Froude number 0.87. Interceptor reduce by 21% drag at Froude number 0.87 and also reduce by 16% trim and 6% heave at Froude number 0.58. Nevertheless, applied interceptor in high Froude number such as more than Froude number 1.16 caused interceptor lose effectiveness due to producing a decisive moment which made negative trim (bow-down) and increase total drag.

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.