The Proceedings Fifth International Conference on Numerical Ship Hydrodynamics (1990) / Chapter Skim
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Computation of the Flow past Shiplike Hull
Computation of the Flow past Shiplike Hull
Pages 295-312
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From page 295... ...
Visonneau ENSM Nantes, France Abstract The present work first details the implementation problems of a numerical procedure for the solution of the Reynolds-averaged Navier-Stokes equations in boundaryfitted coordinates. The procedure is validated using well documented experiments on the HSVA tanker and the comparisons demonstrate the ability of the method to predict ship stern flows.
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From page 296... ...
~ ~ o ~ ~ 2 · ~ c o o ° o ° ° °—C - o 4J ~ - > o ~ c _ ~ ~ ~ ~ _ ~ s ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ E c O ~ ~ ~ 0 0 C ~ `~ C~ ° cn c c °, ° c c E ~ E ° E c 0 ~ r 2.
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From page 297... ...
As a first consequence, the projection phase of the pressurevelocity coupling does not connect always the driving component of the pressure gradient to the corrected velocity component . Because of the strong grid clustering the stiffness of the "threedimensional" pressure matrix is so much increased that standard relaxation techniques usually retained do not converge anymore.
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From page 298... ...
which classically involve the Cartesian velocity components {U°C}-{U,V,W} are partially transformed from the Cartesian rectilinear coordinates {xa}-ix, y, z} in the physical space, to the curvilinear coordinates hi - {k,ll,`} in the so-called computational space. The coordinate transformation is designed in order that the boundaries OB and £ become ~ = const.
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From page 299... ...
2 3 The Flow Equations Apart from the continuity equation -see (2.7) -, the transport equations for the mean momentum, for k and ~ can be written under the following Master Equation (2.14)
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-Step l- In the cell-centered colocated grid approach, where velocity components pressure and turbulent quantities are defined at the center of the control volume the momentum equations (3.9) can be written under the form (3.17~.
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From page 301... ...
are generated by the m~salignment between the coordinate lines and the directions of the velocity components. With respect to the staggered grid approach, it is seen that the D coefficient for the pressure gradient does not depend now on the correspond~ng velocity component.
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Velocity components U V, W as well as pressure data can be compared more extensively (fig.
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The method uses a system of numerically generated curvilinear coordinates and retains the Cartesian velocity components as independent variables. The turbulent closure of the equations is handled with the well-known 303 k-e model.
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G.D. Tzabiras, Numerical and Experimental investigation of the Flow Field at the stern of Double Ship Hulls.
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Chang and K Kaups, A Three Dimensional General Method for Threedimensional Laminar and Turbulent Boundary Layers on Ship Hulls, Proc.
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a, location of velocity components and of pressure.
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, · . 0 .04 .08 .12 .16 .20 .24 Fig.8a - Velocity components and Pressure at a given crosssection X/L = .944, for several depths Z = const., as a function of Y.a, experiments; , computations.
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i2 . i6 .20 .24 Fig.8b, c - Velocity components and Pressure as a function of Y
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ins i~''2_22,'2 Fig.6 - Secondary velocities at several crosssections X = const.; left, experiments; right, computations.
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From page 310... ...
~ x = -157mm i /, /,, ~ /, /, ~ / 32^~" _ ~ , ~ , 1 _', ' ~ , i ; x = -53mm /' i., it,, /'','' /, A, / , - ., /, ~ , ,, , ~ ;.
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Fig. 1 1 - Perspective view of the aft part of the HSVA tanker; skin-friction lines.
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From page 312... ...
(ii) the development of the boundary layer below the overhang is not correctly captured because of the lack of discretization points and a distribution law which is not in agreement with the strong variation of the velocity profiles in the plane y=0.
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