The Proceedings Fifth International Conference on Numerical Ship Hydrodynamics (1990) / Chapter Skim
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Numerical Simulation of Viscous Flow around Practical Hull Form
Numerical Simulation of Viscous Flow around Practical Hull Form
Pages 211-224
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From page 211... ...
A propeller is simulated by giving pressure jump at its position. In order to eliminate skew grid around practical hull form, which violates the computational result, adjustment of grid angle is applied to the grid generated by solving the elliptic partial differential equation.
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From page 212... ...
G I is the contravariant velocity components without the metric normalization, and defined as follows: Gi = a, ju; Ai j and ai j are the metric coefficients for transformation: a;%, = 9~ J DXJ Production term Pk in general curvilinear coordinate is given by: p ~ a, Du; ( ~ ale ~ a, ,'~uj ) (~3' Table 1 shows a, F
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From page 213... ...
: Hull Surface Center plane Water plane Upstream boundary Downst ream boundary Outer boundary : x= 0.0 ~ L .Y= Ye z= 0.0 ~ d : y= 0.0 : z= 0.0 : x=-0.5L : x= 2.0L : r= 0.5L where L, d and ye denote ship length, draft and half b readth of a ship respectively. 2.4 Boundary conditions As for flow field around a fixed model in the uniform flow U
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From page 214... ...
However there are some skew grids near stern region because the grid line is chosen to correspond to the end profile and when these grids are applied to the flow calculation by the present method, the solution diverges. The computational results shown in Fig.5 is the velocity vector near hull surface just before calculation breaks down.
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From page 215... ...
by this method. Fig.9 and Fig.10 show the computational grids for tanker forms with normal stern and IHI B.O.
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From page 216... ...
In the present flow calculation method, the off-diagonal terms in source term in pressure-correction equation are ignored as small quantities in order to save the computational time. It is found, however, that this leads to the breakdown of computational results when there are skew grids in computational domain around practical hull form.
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From page 217... ...
In order to improve the accuracy of the prediction, further examinations are necessary for finite-difference scheme, grid generation, turbulence model, adoption of wall-function and so forth. The final goal of the present study is to build a design code which can evaluate self propulsion factor of a ship taking account rudder effect.
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From page 218... ...
_ - I 1 U—U VI'V2 Prediction with momentum theory U | Propeller position 0.4 _ Vl ~ /i x(m) 0.0 , ~/ 1 1 1 -1 n o.o l.o 1.0 2.0 Fig.4 Computational examination of pressure jump model 218
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From page 219... ...
I\\ \ \ \ ~ \ id,'- \ * : Angle adjusted to be between 45°~135° Fig.8 Adj ustment of grid angle
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From page 220... ...
Bow Part Stern Part Stern Section Fig.9 Generated computational grid ( Tanker form with normal stern ) Row Fort _~ Stern Part Stern Section Fig.10 Generated computational grid ( Tanker form with IHI B.O.
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From page 221... ...
.~ Fig. 15 HU11 surface pressure distribution ( Wigley model, RN=4.5X1O6 )
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From page 222... ...
. ~°~ C, X103 1 ~ o · °'° k/U7XIO' 5'00'0 k/U2 103 5'00'0 / ~ , 5.00.0 5,0 · ~ ~O · · Fig.17 Comparison of turbulent kinetic energy l 1;0 z/d ( Wigley model, RN =4.5xlO6, z/d=O.O )
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From page 223... ...
Exp. Fig.20 The effect of propeller on the calculated and measured wake patterns ( Series-GO Cb=0.6, RN=9.22X1O6 )
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From page 224... ...
1 ' ) ' Fig.22 Calculated and measured wake patterns ( Tanker form with normal stern, RN=7.8X1O6 )
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