Study of Prismatic Planing Model Spray and Resistance Components

The results of a study of prismatic planing model spray and resistance components are presented. The calculated total resistance values are shown to be in good agreement with the measured resistance. The features of the whisker spray and spray blister are discussed along with an experimental technique using wide-beam prismatic models for measuring the spray thickness. A derivation based on energy considerations of the prismatic planing hull pressure resistance component and the spray thickness is presented. The spray thickness values calculated from this formulation are in qualitative agreement with the measured spray thickness. The frictional resistance component obtained from the resistance measurements indicated an extensive laminar flow on the planing model bottom. An acetanilid film was sprayed on the planing model bottom which tripped the laminar-turbulent transition. The CF-values estimated from the acetanilid film pattern were found to be 75 to 90 percent of the CF-values estimated from the corresponding resistance tests.

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ANALISA KOMPONEN HAMBATAN KAPAL IKAN TRADISIONAL DI PERAIRAN CILACAP

Jurnal Kelautan Indonesian Journal of Marine Science and Technology ◽

10.21107/jk.v9i1.958 ◽

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

RESISTANCE COMPONENT ANALYSIS OF TRADITIONAL FISHING BOAT IN CILACAP 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. Keywords: catamaran, Cilacap, slender body method ABSTRAK 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. Kata kunci: catamaran, Cilacap, slender body method

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Point Contact Current Voltage Measurements of 4H-SiC Samples with Different Doping Profiles

Materials Science Forum ◽

10.4028/www.scientific.net/msf.897.287 ◽

2017 ◽

Vol 897 ◽

pp. 287-290 ◽

Cited By ~ 1

Author(s):

Matthias Kocher ◽

Michael Niebauer ◽

Mathias Rommel ◽

Volker Haeublein ◽

Anton J. Bauer

Keyword(s):

Epitaxial Layer ◽

Depth Profile ◽

Point Contact ◽

Surface Preparation ◽

Epitaxial Layers ◽

Depth Profiles ◽

Current Voltage ◽

Measured Resistance ◽

Doping Profiles ◽

Good Agreement

Point contact current voltage (PCIV) measurements were performed on 4H-SiC samples, both for n- an p-doped epitaxial layers as well as samples with rather shallow doping profiles realized by N- or Al-implantation in a range from 1016 cm-3 to 1019 cm-3. Surface preparation and measurement parameters were investigated in order to determine their influence on the measured resistance profiles. Furthermore depth profile measurements were performed on both an epitaxial layer as well as on implanted samples. These depth profiles could be measured reproducibly and showed good agreement with expected profiles for Al-implanted samples as well as for epitaxial layer whereas for N-implanted samples deviations between measured and expected profiles could be observed. It could be proven that PCIV profiling technique is a promising method for characterizing doped profiles in 4H-SiC, especially on Al-implanted samples.

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Stern Flap–Waterjet–Hull Interactions and Mechanism: A Case of Waterjet-Propelled Trimaran With Stern Flap

Journal of Offshore Mechanics and Arctic Engineering ◽

10.1115/1.4045498 ◽

2020 ◽

Vol 142 (2) ◽

Author(s):

Lei Zhang ◽

Jianing Zhang ◽

Yuchen Shang

Keyword(s):

High Efficiency ◽

Navier Stokes ◽

Local Effects ◽

Resistance Components ◽

Leading Role ◽

Resistance Reduction ◽

Sinkage And Trim ◽

Improved Performance ◽

Design Speed ◽

Pressure Resistance

Abstract To research the stern flap (SF) and waterjet–hull interaction, unsteady Reynolds-averaged Navier–Stokes (URANS) simulations for a waterjet-propelled trimaran considering sinkage and trim are performed. Uncertainty analysis of the numerical results for the bare hull (BH) model is presented. At the design speed Froude number (Fr) of 0.6 and under displacement state, the model-scaled trimaran, installed with stern flaps of varied angle and length, tests the BH and self-propulsion (SP) performance based on URANS simulations. For the resistance, the global effects due to motions and the local effects of SF, waterjets (WJ), and the coupled term between SF and WJ on the hull are separately analyzed. Taking the waterjet propulsion system into account, an SP model with reasonable stern flap effectively reduces the trim, the resistance acting on the hull and the waterjet thrust deduction which contributes to energy-saving and high-efficiency propulsion. The mechanism of the improved performance of the waterjet-propelled trimaran with stern flaps is discussed. For the resistance increment, the global effects, the local effects of SF and WJ are the major reason for resistance increase, and the nonlinear coupled term of local effects contributes to the resistance reduction most. In addition, the different resistance components of frictional, hydrostatic, and hydrodynamic are separately researched, which shows that the pressure resistance components plays a leading role in the total resistance reduction in the SP model with the suitable SF.

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Numerical simulation of turbulent boundary layers of surfaces covered with foul release and antifouling coatings

Journal of Naval Architecture and Marine Engineering ◽

10.3329/jname.v13i1.26017 ◽

2016 ◽

Vol 13 (1) ◽

pp. 17-26

Author(s):

Sadra Kianejad ◽

Naznin Ansarifard

Keyword(s):

Frictional Resistance ◽

Reynolds Numbers ◽

Resistance Coefficient ◽

Cfd Modeling ◽

Test Plate ◽

Plate Length ◽

Numerical Studies ◽

Antifouling Coatings ◽

Coating Characteristics ◽

Good Agreement

In order to compare the frictional resistance of three kinds of ships hull coatings (Foul Release, SPC copper, SPC TBT) in the unfouled conditions, the numerical studies have been made. Simulations have been carried out for different Reynolds numbers in the range of 2.85 × 5.5 × based on the plate length and flow velocity. Antifouling coatings have a larger mean roughness than Foul Release. The results have indicated that frictional resistance coefficient of Foul Release test plate is lower than SPC copper and SPC TBT test plates. The total resistance obtained by computational fluid dynamics has been compared with the experimental data and good agreement in results has been found which those have shown the ability of CFD modeling in calculating of fluid flow resistance by considering the coating characteristics.

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The wave-making resistance of ships: a theoretical and practical analysis

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character ◽

10.1098/rspa.1909.0033 ◽

1909 ◽

Vol 82 (554) ◽

pp. 276-300 ◽

Cited By ~ 11

Keyword(s):

Experimental Study ◽

Theoretical Investigation ◽

Frictional Coefficient ◽

Frictional Resistance ◽

Total Resistance ◽

Forward Motion ◽

Practical Analysis ◽

Hydrodynamical Theory

The theoretical investigation of the total resistance to the forward motion of a ship is usually simplified by regarding it as the sum of certain independent terms such as the frictional, wave-makings and eddy-making resistances. The experimental study of frictional resistance leads to a formula of the type. R s =ƒSV m , (1) where S is the wetted surface, V the speed,ƒ a frictional coefficient, and m an index whose value is about 1.83. After deducting from the total resistance the frictional part calculated from a suitable formula of this kind, the remainder is called the residuary resistance. Of this the wave-making resistance is the most important part; the present paper is limited to the study of wave-making resistance, and chiefly its variation with the speed of the ship. The hydrodynamical theory as it stands at present may be stated briefly.

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Experimental Investigation of Turbulent Boundary Layer Over Smooth Flat Plate With Towing Tank: Attempt of Measurement of Frictional Stress

Volume 1: Symposia, Parts A and B ◽

10.1115/fedsm2007-37220 ◽

2007 ◽

Author(s):

Kiyoto Mori ◽

Hiroki Imanishi ◽

Yoshiyuki Tsuji ◽

Masashi Kashiwagi ◽

Masaru Inada ◽

...

Keyword(s):

Boundary Layer ◽

Flat Plate ◽

Frictional Resistance ◽

Reynolds Numbers ◽

Sufficient Accuracy ◽

Frictional Stress ◽

Towing Tank ◽

High Reynolds Numbers ◽

Pressure Resistance ◽

High Reynolds

The purpose of this study is to evaluate the frictional resistance with sufficient accuracy and to evaluate the drag coefficient at high Reynolds numbers. We have measured the resistance of flat plate with using a towing tank. Correcting the wave-making resistance, pressure resistance, and drag on turbulence simulator, it is found that the measured frictional resistance is smaller than the Karman-Schoenherr formula. But it agrees with the values suggested by Osaka et. al and Osterlund et. al.

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Research on Ship Hull Optimisation of High-Speed Ship Based on Viscous Flow/Potential Flow Theory

Polish Maritime Research ◽

10.2478/pomr-2020-0002 ◽

2020 ◽

Vol 27 (1) ◽

pp. 18-28

Author(s):

Zhang Baoji

Keyword(s):

High Speed ◽

Design Method ◽

Frictional Resistance ◽

Linear Wave ◽

Total Resistance ◽

Friction Resistance ◽

Resistance Reduction ◽

Before And After ◽

Reduction Effect ◽

Cfd Method

AbstractIn order to quickly obtain practical ship forms with good resistance performance, based on the linear wave-making resistance theory, the optimal design method of ship forms with minimum total resistance is discussed by using the non-linear programming (NLP) method. Taking the total resistance as the objective function (the Michell integral is used to calculate the wave-making resistance and the equivalent plate friction resistance formula is used to calculate the frictional resistance), the hull surface offset as the design variable and appropriate displacement as the basic constraints, and considering the additional constraints, the hull bow shape and the whole ship are optimised, and an improved hull form is obtained. The resistance of the ship before and after optimisation is calculated by the CFD method to further evaluate the resistance reduction effect and performance after optimisation. Finally, an example of optimisation calculation of an actual high-speed ship is given. The obvious resistance reduction results confirm the reliability of the optimisation design method.

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Research on a method of hull form design based on wave-making resistance optimization

Polish Maritime Research ◽

10.2478/v10012-012-0027-1 ◽

2012 ◽

Vol 19 (3) ◽

pp. 16-25 ◽

Cited By ~ 2

Author(s):

Jianglong Sun ◽

Xujian Lv ◽

Weibin Liu ◽

Hanwen Ning ◽

Xianwen Chen

Keyword(s):

Cross Section ◽

Frictional Resistance ◽

Wave Resistance ◽

Total Resistance ◽

Hull Form ◽

Mathematical Procedure ◽

Result Show ◽

Form Design ◽

Hull Form Design ◽

Resistance Performance

ABSTRACT In this paper, we consider an optimization of the hull shape in order to minimize the total resistance of a ship. The total resistance is assumed to be the sum of the wave resistance computed on the basis of the thin-ship theory and the frictional resistance. Smoothness of hull lines is proved with mathematical procedure, in which differentials of the hull lines functions are analyzed. The wave-making resistance optimization, involving a genetic algorithm, uses Michell integral to calculate wave resistance. A certain hull form is generated by the method using cross section information of a modified DTMB model ship 5415 and a comparative experiment is carried out. Experimental and calculation result show that the method is of good adaptability for designing certain types of ships with excellent resistance performance.

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The Interaction of Frictional Slip and Adhesion for a Stiff Sphere on a Compliant Substrate

Journal of Applied Mechanics ◽

10.1115/1.4045794 ◽

2020 ◽

Vol 87 (3) ◽

Cited By ~ 5

Author(s):

R. M. McMeeking ◽

M. Ciavarella ◽

G. Cricrì ◽

K.-S. Kim

Keyword(s):

Strain Energy ◽

Elastic Strain Energy ◽

Frictional Resistance ◽

Linear Elastic ◽

Adhesion Behavior ◽

Stiff Material ◽

Surface Microstructures ◽

Work Done ◽

Frictional Slip ◽

Good Agreement

Abstract How friction affects adhesion is addressed. The problem is considered in the context of a very stiff sphere adhering to a compliant, isotropic, linear elastic substrate and experiencing adhesion and frictional slip relative to each other. The adhesion is considered to be driven by very large attractive tractions between the sphere and the substrate that can act only at very small distances between them. As a consequence, the adhesion behavior can be represented by the Johnson–Kendall–Roberts model, and this is assumed to prevail also when frictional slip is occurring. Frictional slip is considered to be resisted by a uniform, constant shear traction at the slipping interface, a model that is considered to be valid for small asperities and for compliant elastomers in contact with stiff material. A simple model for the interaction of friction and adhesion is utilized, in which some of the work done against frictional resistance is assumed to be stored reversibly. This behavior is considered to arise from surface microstructures associated with frictional slip such as interface dislocations, where these microstructures store some elastic strain energy in a reversible manner. When it is assumed that a fixed fraction of the work done against friction is stored reversibly, we obtain good agreement with data.

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Shear Design of Wide Beam Ribbed Slabs

The Journal of The Institution of Engineers, Malaysia ◽

10.54552/v72i3.22 ◽

2011 ◽

Vol 72 (3) ◽

Author(s):

Teck Leong Lau

Keyword(s):

Test Data ◽

Design Method ◽

Code Design ◽

Wide Beam ◽

Empirical Assumption ◽

Shear Design ◽

Basic Code ◽

Shear Area ◽

Good Agreement ◽

Made In

A method for the shear design of wide beam ribbed slabs is proposed. The method modifies the current UK code design method for solid slabs by applying a shear area factor which reduces the area of the code critical shear perimeter to take account of the loss of shear area from that of a solid slab. The proposed method gives good agreement with test data for internal column situations, and underestimates the strength at edge columns. The conservativeness in relation to edge columns arises because of an empirical assumption made in the basic code method for solid slabs and is not due to the modification that it is proposed for wide beam ribbed slabs.

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