The Proceedings Fifth International Conference on Numerical Ship Hydrodynamics (1990) / Chapter Skim
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On the Numerical Solution of the Turbulent Flow-Field past Double Ship Hulls at Low and High Reynolds Numbers
On the Numerical Solution of the Turbulent Flow-Field past Double Ship Hulls at Low and High Reynolds Numbers
Pages 539-552
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From page 539... ...
, [3] .The model has been numerically tested at a low Reynolds number of SxlOb, which corresponds to the test conditions and at a high Reynolds number of Sx108, which corresponds to a full size ship At the low Re No numerics results at the stern region, obtained by either using input conditions amidships from experimental data or solving the complete flow field around the ship hull have been compared to experimental results.
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From page 540... ...
2x / L= -.8 `~i\3,43 zx/L= .9 zx/ L=.987 Re 5X10 Re 5X108 Fig. 1 Orthogonal curvi linear grids at various sections 540
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From page 541... ...
= h h h [ + ~ + 7~ ] The stress tensor components appearing on the right hand side of equation (l)
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From page 542... ...
The values of k and ~ at the same boundary are assumed to be equal to zero. The corresponding input boundary conditions for the velocity components and turbulence quantities at the inlet plane UII of the second calculation domain are determined from the front part flow solution by linear interpolation.
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From page 543... ...
3.1 Low Reynolds Number Computations For the front part calculations, a 32x20x61 grid was used where 32 is the number of grid nodes along the girth, 20 the number of nodes along the normal direction to the section contour and 61 the number of transverse sections. The inlet plane of the calculation domain was placed at 2X/I'-1.2 and the exit plane at 2X/I'0.30.
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From page 544... ...
Discussion of the Results 4.1 Low Reynolds Number The calculated pressures along the girth of venous sections of the fron part of the ship compare well with the experiment values, Figs. 6 a to 6 d, when corrected for blockage effects as proposed by Larsson [15]
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From page 545... ...
lo Ax 1 14~, a)
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From page 546... ...
As expected the potential flow solution yields larger values than the viscous flow solutions, with the differences diminishing with increasing Re.No. The girthwise values of CF are more constant for the high Re.No., whereas CF has very high values near the keel for the low Re.No.
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From page 547... ...
11 o -- -lo 11~ o = o < + + o o o o o a\ o x air r U O .
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From page 549... ...
In this endeavour we are encouraged from similar trends for the case of a body of revolution As it is well known, ship resistance predictions are based on model experiments, on a flat plate friction line and on appropriate scaling laws. We now consider that the examined low Re.No case represents model tests with results shown In Table 1, which also contains the results of a corresponding full scale experiment.
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From page 550... ...
and Spalding, D.B., "A method of predict~ng three-dimensional turbulent flows around ship hulls", 1st Int.Symposium on Ship Viscous Resistance, Goteborg (1978)
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From page 551... ...
024x10 -3 CF 3.73 ~0-3 Re = 5x10,3 2.560 10 3 0.77 x1o ~ 3 1. 79XlO -3 Table 2: Calculation of ship total resistance coefficient by the form factor and Froude method .
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