Global optimization of trimaran hull form to get minimum resistance by slender body method

2021 ◽  
Vol 43 (2) ◽  
Author(s):  
Amin Nazemian ◽  
Parviz Ghadimi
Keyword(s):  
Global Optimization ◽  
Slender Body ◽  
Hull Form ◽  
Minimum Resistance ◽  
Body Method

Comparison of Two Base-Potentials for a Slender-Body Method

2012 ◽  
Author(s):  
Mahmoud Alidadi ◽  
Sander Calisal
Keyword(s):  
Three Dimensional ◽  
Slender Body ◽  
Surface Boundary ◽  
Two Dimensional ◽  
Three Dimensional Flow ◽  
Wave Elevation ◽  
Surface Boundary Conditions ◽  
Perturbation Potential ◽  
Order Of Magnitude ◽  
Body Method

The effects of two base-potentials on the accuracy of a slender-body method are studied in this paper. In the formulation for this method which is developed for the slender ships, the velocity potential is decomposed into a base-potential and a perturbation potential. Then using an order of magnitude analysis, the three-dimensional flow problem is simplified into a series of two-dimensional problems for the perturbation potential. These two-dimensional problems are solved with the linearized free surface boundary conditions, using a mixed Eulerian-Lagrangian method. Finally for the two base-potentials, the numerical wave elevation along a Wigleyull are compared with the experimental results.

Numerical Analysis of the Influence of Above-Water Bow Form on Added Resistance Using Nonlinear Slender Body Theory

2005 ◽  
Vol 49 (03) ◽  
pp. 191-206
Author(s):  
Hajime Kihara ◽  
Shigeru Naito ◽  
Makoto Sueyoshi
Keyword(s):  
Three Dimensional ◽  
Wave Force ◽  
Slender Body ◽  
Added Resistance ◽  
Slender Body Theory ◽  
Hull Form ◽  
Nonlinear Properties ◽  
Head Waves ◽  
The Time Domain ◽  
Body Theory

A nonlinear numerical method is presented for the prediction of the hydrodynamic forces that act on an oscillating ship with a forward speed in head waves. A "parabolic" approximation of equations called "2.5D" or "2D+T" theory was used in a three-dimensional ship wave problem, and the computation was carried out in the time domain. The nonlinear properties associated with the hydrostatic, hydrodynamic, and Froude-Krylov forces were taken into account in the framework of the slender body theory. This work is an extension of the previous work of Kihara and Naito (1998). The application of this approach to the unsteady wave-making problem of a ship with a real hull form is described. The focus is on the influence of the above-water hull form on the horizontal mean wave force. Comparison with experimental results demonstrates that the method is valid in predicting added resistance. Prediction of added resistance for blunt ships is also shown by example.

ON THE MACRO HYDRODYNAMIC DESIGN OF HIGHLY EFFICIENT MEDIUM- SPEED CATAMARANS WITH MINIMUM RESISTANCE

2021 ◽  
Vol 154 (A3) ◽  
Author(s):  
M Haase ◽  
J Binns ◽  
G Thomas ◽  
N Bose ◽  
G Davidson ◽  
...  
Keyword(s):  
High Speed ◽  
Preliminary Design ◽  
Total Resistance ◽  
Hull Form ◽  
Transport Efficiency ◽  
New Class ◽  
Highly Efficient ◽  
Medium Speed ◽  
Resistance Curves ◽  
Minimum Resistance

A new class of fuel-efficient and environmentally friendly twin-hull vessels is currently under development. Compared to high-speed catamarans, a significant reduction in speed combined with an increase in deadweight tonnes will lead to a highly efficient medium-speed catamaran design. Recently-built conventional and high-speed ferries are compared to each other in terms of length, speed, deadweight and transport efficiency to classify the new design. The goal of this study is to find a preliminary macro design point for minimum total resistance by considering the main particulars of the catamaran vessel: block coefficient, prismatic coefficient and slenderness and separation ratios of the demihulls. Publications containing recommendations towards the optimum hull form parameters for moderate Froude numbers are reviewed and existing experimental data analysed to identify parameters for this new class of vessel. Designs with varied L/BOA-ratios and constant deck area are compared to find configurations of low total resistance for carrying a nominated deadweight at a particular speed, the associated change of the light ship weight has been taken into account. Two different model test series of catamaran models have been considered and their resistance curves agreed to each other. Recommendations are made; with the most important being the vessel should not exceed a speed of Fr = 0.35, with optimal prismatic coefficients around CP ≈ 0.5 and low transom immersion. This study presents the preliminary design of medium-speed single and twin-hull vessels for operations close to hump speed.

The Design of an Eight-Oared Rowing Shell

1993 ◽  
Vol 30 (02) ◽  
pp. 84-99
Author(s):  
Carl A. Scragg ◽  
Bruce D. Nelson
Keyword(s):  
Shallow Water ◽  
High Speed ◽  
Hull Form ◽  
Model Scale ◽  
Minimum Drag ◽  
Final Design ◽  
Minimum Displacement ◽  
Resistance Curves ◽  
Hull Forms ◽  
Minimum Resistance

Rules governing the design of rowing shells do not restrict basic hull parameters. In designing a new eight-oared rowing shell for international ard Olympic competition, the authors sought a high speed, minimum drag hull form, subject only to the constraints on minimum displacement and roll stability. An investigation of optimum hull parameters using analytically determined resistance curves was made. Optimum hull parameters for both deep and shallow water racing are presented. Using the hull parameters determined for minimum resistance at racing speeds in shallow water, several new hull forms were created and analyzed in both deep and shallow water. Two promising final design candidates were proposed for model-scale testing. Results of both steady and unsteady towing tests are presented.

An Evaluation of Model Ship Total Resistance by Measured and Different Methods

2011 ◽  
Vol 110-116 ◽  
pp. 4433-4438
Author(s):  
Kay Thwe ◽  
Gao Gao
Keyword(s):  
Experimental Data ◽  
Experimental Test ◽  
Slender Body ◽  
Analytical Prediction ◽  
Total Resistance ◽  
Challenging Problem ◽  
Flow Solver ◽  
Solution Methods ◽  
Naval Architect ◽  
Body Method

Prediction of total hull resistance has been investigated for many decades and it is still a challenging problem for naval architect. In this paper, the total resistance of round bilge monohull Model 100A is predicted by potential flow solver, Shipflow by Flowtech International AB, the commercial Reynold Average Navier Stroke (RANS) solver Fluent by Fluent, Inc., and analytical prediction by Slender Body Method (SBM). The total resistance was predicted by each code for the different model speeds (0.6m/s to 4.5m/s) and compared with experimental test data. The Fluent predictions were found to be in agreement with the experimental data in lower speed (0.6m/s to 2.5m/s). Shipflow results were more closed to experimental results than Fluent. Comparisons between the different solution methods were also discussed with the particular grid generation methods and numerical solution techniques. It is found that Slender Body Method can solve as easy and simple and it is effective to predict total resistance of thin ship monohull.

An Optimization Study of TriSWACH Side-Hull Position for Minimum Resistance in Calm Water

2017 ◽  
Author(s):  
Yufei Ai ◽  
Yulin Zhao ◽  
Raju Datla
Keyword(s):  
Froude Number ◽  
Water Resistance ◽  
Hydrodynamic Characteristics ◽  
Hull Form ◽  
Optimization Study ◽  
Seakeeping Performance ◽  
Stevens Institute ◽  
Calm Water ◽  
Institute Of Technology ◽  
Minimum Resistance

TriSWACH is a promising novel hull form for its reduced resistance, larger deck area and good seakeeping performance. This paper aims to determine an optimal sidehull position for TriSWACH based on the minimum resistance in calm water. STAR-CCM+, a RANS-based commercial CFD tool and a potential flow code Michelet are compared in their calculations of resistance. Four different side-hull positions of the TriSWACH operated within Froude number from 0.1 to 0.5 with increment 0.05 are considered for the numerical simulations. The simulation results are further validated by the model tests performed in Stevens Institute of Technology Davidson Laboratory towing tank. The comparison shows that STAR-CCM+ RANS codes can predict TriSWACH’s hydrodynamic characteristics in calm water with high accuracy. Finally, TriSWACH's optimal side-hulls’ position was discussed based on calm water resistance within different Froude number ranges.

scholarly journals ANALISA KOMPONEN HAMBATAN KAPAL IKAN TRADISIONAL DI PERAIRAN CILACAP

2016 ◽  
Vol 9 (1) ◽  
pp. 1
Author(s):  
S Samuel
Keyword(s):  
Water Resistance ◽  
Frictional Resistance ◽  
Slender Body ◽  
Resistance Components ◽  
Fishing Boat ◽  
Calm Water ◽  
Double Hull ◽  
Traditional Fishing ◽  
Body Method ◽  
Resistance Component

<p><em>RESISTANCE COMPONENT ANALYSIS OF TRADITIONAL FISHING BOAT IN CILACAP</em></p><p><em><br /></em></p><p><em>Monohull fishing boats used to catch fish is modified into a catamaran boat. The purpose of this modification is to get more fish. Catamaran ship has a double hull, but with the double hull ships resulted in increasingly complex resistances. It is interesting to study in depth about the resistance components of Catamaran boat. Resistance Components not only consist of surge resistance, frictional resistance, and the form resistance but with the distance between demihull causing interference waves. There are many research results of Catamaran boat in that aspect, but the data and information obtained from the experiment is still inadequate. In addition, there is still lack of accuracy particularly in predicting interference resistance component in calm water (calm-water resistance) as a result of the distance between the demihull. This study aims to describe the resistance component at Catamaran boat by using slender body method.</em><strong><em></em></strong></p><p align="center"><strong> </strong></p><p><strong>Keywords</strong>: <em>catamaran, Cilacap, slender body method</em></p><p> </p><p align="center"><strong>ABSTRAK</strong></p><p align="center"><strong> </strong></p><p><em>Kapal ikan monohull yang biasa digunakan untuk mencari ikan dimodifikasi menjadi kapal catamaran. Tujuan modifikasi ini untuk mendapatkan muatan ikan yang lebih banyak. Kapal Catamaran mempunyai dua lambung, tetapi dengan adanya dua lambung mengakibatkan hambatan kapal semakin kompleks. Menarik untuk dikaji lebih lanjut tentang komponen hambatan kapal Catamaran. Komponen hambatan tidak hanya terdiri dari hambatan gelombang, hambatan gesek, dan hambatan bentuk namun dengan adanya jarak antar demihull sehingga menimbulkan interferensi gelombang. Sudah banyak dijumpai hasil riset kapal Catamaran pada aspek tersebut, tetapi data dan informasi yang diperoleh dari eksperimen masih kurang memadai. Disamping itu, masih ditemukan ketidak-akurasian khususnya dalam memprediksi interferensi komponen hambatan pada air tenang (calm-water resistance) akibat dari adanya jarak antar demihull tersebut. Penelitian ini bertujuan untuk memaparkan komponen hambatan pada kapal Catamaran dengan menggunakan slender body method. </em></p><p> </p><p><strong>Kata kunci</strong>: <em>catamaran, Cilacap, slender body method</em></p>

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