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TECHNICAL PAPERS

Scars and Vortices Induced by Ship Bow and Shoulder Wave Breaking

[+] Author and Article Information
A. Olivieri, F. Pistani, E. F. Campana

INSEAN, National Ship Research Institute, Via di Vallerano 139, 00128 Rome, Italy

R. Wilson

IIHR, Hydroscience & Engineering, The University of Iowa, Iowa City, Iowa 52242-1585; UT SimCenter, The University of Tennessee at Chattanooga, Chattanooga, TN 37403

F. Stern

IIHR, Hydroscience & Engineering, The University of Iowa, Iowa City, IA 52242-1585

http://www.chesapeakebay.net/info/ecoint3cfm

J. Fluids Eng 129(11), 1445-1459 (Jun 07, 2007) (15 pages) doi:10.1115/1.2786490 History: Received April 17, 2006; Revised June 07, 2007

Experimental data are provided for physical understanding and computational fluid dynamics (CFD) validation for the surface combatant David–Taylor model basin Model 5415 bow and shoulder wave breaking. A photographic study was conducted using 5.72m replica and 3.05m geosim models of Model 5415 over a range of Froude numbers (Fr) to identify Fr and scale effects on wave breaking and choose the best Fr for the local flow measurements, which include near- and far-field means and rms wave elevation and mean velocity under the breaking waves. The larger model and Fr=0.35 were selected due to the large extents of quasisteady plunging bow and spilling shoulder wave breaking. A direct correlation is shown between regions of wave slope larger than 17deg and regions of large rms in wave height variation. Scars characterized by sudden changes in the mean wave height and vortices induced by wave breaking were identified. Complementary CFD solutions fill the gaps in the relatively sparse measurements enabling a more complete description of the bow and shoulder wave breaking and induced vortices and scars. The combined results have important implications regarding the modeling of the bubbly flow around surface ships, especially for bubble sources and entrainment.

Copyright © 2007 by American Society of Mechanical Engineers
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References

Figures

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Figure 1

Cross sections and profile views of IIHR Model 5512 and INSEAN Model 2340 with reference frame

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Figure 2

Finger probe and capacitance wires measured area

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Figure 3

Measurement grid at x=0.5

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Figure 4

Selected cross planes for the velocity measurements

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Figure 5

Fr=0.28: Model 5512 side and front views ((a) and (b)); Model 2340 side and front views ((c) and (d)); evidence of capillaries for 2340 (e); full-scale side and front views ((f) and (g)).

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Figure 6

Fr=0.35: Model 5512 side and front views ((a) and (b)); Model 2340 side and front views ((c) and (d)); full-scale side and front views ((e) and (f)).

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Figure 7

Fr=0.35 rolls and scars generation and development ((a)–(c)); shoulder breaking wave (d)

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Figure 8

Fr=0.45: Model 5512 side and front views ((a) and (b)); Model 2340 side and front views ((c) and (d));

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Figure 9

Perspective view of the mean value of the wave pattern

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Figure 10

Mean wave elevation measured by servo-mechanic probe; dash-dot lines indicated the scars locations

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Figure 11

rms value of the wave elevation measured by servo-mechanic probe; thin dash-dot lines indicate the scars locations and straight thick dash-dot line indicates the shoulder wave breaking

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Figure 12

Traces of the scars generated at the bow. Mean wave elevation (left) and rms value (right) of the wave elevation

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Figure 13

The cross flow vectors and axial velocity contours (left) and axial vorticity contours (right) at the four measurement sections (a) x=0.15, (b) x=0.20, (c) x=0.40, and (d) x=0.50. Measured mean wave elevation transverse cuts (solid lines) +∕− rms (dashed lines)

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Figure 14

CFD and experimental free-surface contours. The presence of the scars is clearly visible in the bow region.

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Figure 15

Bow wave details for CFD solution

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Figure 16

Axial velocity (x=0.15): INSEAN experiments (top); IIHR CFD (bottom)

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Figure 17

Transverse velocity (x=0.15): INSEAN experiments (top); IIHR CFD (bottom)

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Figure 18

Vertical velocity (x=0.15): INSEAN experiments (top); IIHR CFD (bottom)

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Figure 19

Axial velocity (x=0.40) INSEAN experiments (top); IIHR CFD (bottom)

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Figure 20

Transverse velocity (x=0.40): INSEAN experiments (top); IIHR CFD (bottom)

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Figure 21

Vertical velocity (x=0.40): INSEAN experiments (top); IIHR CFD (bottom)

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Figure 22

Experimental (top) and numerical (bottom) axial vorticity contours at x=0.40

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Figure 23

CFD solution with under free surface (left) and above free surface (right): transverse sections of the wave contours are shown in black and axial vorticity contours are shown in blue (CW) and red (CCW)

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Figure 24

CFD solution bow wave breaking and induced vortices and scars

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Figure 25

Free-surface streamlines and vorticity contours near the bow

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Figure 26

Wave steepness (top) and rms value (bottom) of the wave elevation

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