Unsteady Numerical Simulation of the Behavior of a Ship Moving in Head Sea

2019 ◽  
Author(s):  
Adrian Lungu
Keyword(s):  
Free Surface Flow ◽  
Surface Flow ◽  
Incoming Wave ◽  
Grid Convergence ◽  
Head Waves ◽  
Calm Water ◽  
Unsteady Numerical Simulation ◽  
Resistance Coefficients ◽  
Regular Head Waves ◽  
Numerical Approaches

Abstract The paper follows a previous work of the author that dealt with ship resistance and self-propulsion numerical investigations, proposing a series of numerical simulations performed to assess the seakeeping performances of the KCS model which moves in regular head waves. Various simulations of the free-surface flow around the hull equipped with rudder moving either in calm water or in heading waves are proposed. For the calm water case, in which a series of six Fr numbers is considered, verification and validation based on the grid convergence tests are performed. Then, a series of five different simulations for various incoming wave characteristics are presented and discussed in every detail. Comparisons with the experimental data [1], [2] are provided aimed at validating the numerical approaches in terms of the total resistance coefficients as well as the heave and pitch motions characteristics. Several remarks will conclude the findings of the present work.

scholarly journals Full-Scale CFD Analysis of Double-M Craft Seakeeping Performance in Regular Head Waves

2021 ◽  
Vol 9 (5) ◽  
pp. 504
Author(s):  
Deniz Ozturk ◽  
Cihad Delen ◽  
Simone Mancini ◽  
Mehmet Ozan Serifoglu ◽  
Turgay Hizarci
Keyword(s):  
Full Scale ◽  
Stokes Wave ◽  
Added Resistance ◽  
Motion Responses ◽  
Seakeeping Performance ◽  
Head Waves ◽  
Calm Water ◽  
Maximum Improvement ◽  
Fifth Order ◽  
Regular Head Waves

This study presents the full-scale resistance and seakeeping performance of an awarded Double-M craft designed as a 15 m next-generation Emergency Response and Rescue Vessel (ERRV). For this purpose, the Double-M craft is designed by comprising the benchmark Delft 372 catamaran with an additional center and two side hulls. First, the resistance and seakeeping analyses of Delft 372 catamaran are simulated on the model scale to verify and compare the numerical setup for Fr = 0.7. Second, the seakeeping performance of the full-scale Double-M craft is examined at Fr = 0.7 in regular head waves (λ/L = 1 to 2.5) for added resistance and 2-DOF motion responses. The turbulent flow is simulated by the unsteady RANS method with the Realizable Two-Layer k-ε scheme. The calm water is represented by the flat VOF (Volume of Fluid) wave, while the incident long waves are represented by the fifth-order Stokes wave. The residual resistance of the Double-M craft is improved by 2.45% compared to that of the Delft 372 catamaran. In the case of maximum improvement (at λ/L = 1.50), the relative added resistance of the Double-M craft is 10.34% lower than the Delft 372 catamaran; moreover, the heave and pitch motion responses were 72.5% and 35.5% less, respectively.

Numerical Prediction of the Propulsion Characteristics of Ships in Waves

2016 ◽  
Author(s):  
Sebastian Sigmund ◽  
Ould el Moctar
Keyword(s):  
Equations Of Motion ◽  
Open Water ◽  
Computational Effort ◽  
The Self ◽  
Experimental Results ◽  
Characteristic Change ◽  
Flow Solver ◽  
Head Waves ◽  
Calm Water ◽  
Regular Head Waves

The influence of regular head waves on the propulsion characteristics of a twin screw cruise ship is investigated using RANS based flow-solver. Propeller open water characteristics are determined at first by computing the propeller forces in homogeneous inflow. Then, computations of the towed model without propeller and of the self-propelled model in calm water are performed to obtain the propulsion characteristics in calm water. Afterwards, the total resistance as well as the forces of the self-propelled model in regular head waves are computed. All computations are performed using a RANS based flow-solver coupled with the six-degrees-of-freedom equations of motion. The sliding interface method is used to allow the rotation of the geometrically modelled propeller, when needed. Computations are performed using the same numerical grids to keep errors originating on different spatial and temporal discretization as small as possible. Grid studies are performed to evaluate discretization errors of each mesh region, namely the hull region and the rotating propeller region, separately. The numerical results are compared with experimental results obtained from physical tests. It is shown, that RANS is capable of investigating the propulsion behavior of a ship in regular head waves, but to the cost of high computational effort. Fair agreement between numerical and experimental results is obtained. All results show that the propulsion characteristic change in waves. It is also found, that this is mainly caused by the change of the propeller efficiency due to a different propulsion point as a consequence of the added resistance in waves.

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

Kapal ◽  
2021 ◽  
Vol 18 (2) ◽  
pp. 111-118
Author(s):  
Ahmad Firdhaus ◽  
I Ketut Suastika ◽  
Kiryanto Kiryanto ◽  
Samuel Samuel
Keyword(s):  
Cfd Simulation ◽  
Turbulence Models ◽  
Free Surface Flow ◽  
Surface Flow ◽  
Flow Solver ◽  
Source Codes ◽  
Ship Resistance ◽  
Surface Ship ◽  
Calm Water ◽  
Volume Method

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.

scholarly journals NUMERICAL INVESTIGATION OF INTERCEPTOR EFFECT ON SEA KEEPING BEHAVIOUR OF PLANING HULL ADVANCING IN REGULAR HEAD WAVES

Brodogradnja ◽  
2021 ◽  
Vol 72 (2) ◽  
pp. 73-92
Author(s):  
Jangam Suneela ◽  
◽  
Prasanta Sahoo ◽  
Keyword(s):  
Numerical Data ◽  
Navier Stokes ◽  
Hydrodynamic Characteristics ◽  
Head Waves ◽  
Calm Water ◽  
Vessel Response ◽  
Planing Vessel ◽  
Motion Characteristics ◽  
The Impact ◽  
Regular Head Waves

In this paper an attempt has been made to assess the capability of numerical algorithm based on Reynolds Averaged Navier Stokes (RANS) for predicting the motion characteristics of the planing hull in calm water and regular waves. The focus of the present study is the impact of interceptors on the sea keeping quality of a planing vessel investigated through the application of numerical methods. The wave properties such as wavelength and wave height are taken into consideration to investigate the effect of wave steepness on vessel response. It is found that numerical data can efficiently simulate the motion attitude and the hydrodynamic characteristics of planing craft in regular head waves. The planing hull with and without interceptor fitted at the transom is simulated in numerical wave tank. The results show reduction in heave and pitch motions which gave favorable sea keeping behavior for the hull fitted with interceptor. The numerical solution is useful for the preliminary prediction of navigation safety during sailing.

Numerical Investigation for Resistance Characteristics of LNG Carrier

2014 ◽  
Vol 69 (7) ◽  
Author(s):  
A. Y. Sian ◽  
A. Maimun ◽  
A. Priyanto ◽  
Yasser M. Ahmed ◽  
M. Nakisa ◽  
...  
Keyword(s):  
Free Surface ◽  
Free Surface Flow ◽  
General Purpose ◽  
Surface Flow ◽  
Liquefied Natural Gas ◽  
Wave Profile ◽  
Navier Stokes ◽  
Hull Form ◽  
Towing Tank ◽  
Calm Water

Reynolds Averaged Navier-Stokes (RANS) computations are conducted with general purpose CFD solver Fluent to examine the resistance and viscous free surface flow of Liquefied Natural Gas (LNG) carrier hull form in calm water. Shear-stress transport k-w turbulence model and multiphase volume of fluid (VOF) free surface employed. The resistance characteristics and wave profile of the LNG model also investigated. Model tests were conducted in towing tank for validation of the computed results. Overall results agree fairly well with experimental data, reveals the feasibility of RANS method in practical prediction of LNG resistance characteristics.

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