| Title: | LABORATORY STUDY OF TURBULENT FLOW STRUCTURES IN BREAKING WAVES BY PARTICLE IMAGE VELOCIMETRY |
| DOI No: | 10.1142/9789812709554_0028 |
| Source: | COASTAL ENGINEERING 2006 (pp 325-336)
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| Author(s): | Francis C. K. Ting
Department of Civil and Environmental Engineering, South Dakota State University, Brookings, South Dakota, 57007, USA
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| Abstract: | The instantaneous turbulent velocity field associated with a broken solitary wave propagating on a plane slope was measured in the longitudinal transverse plane in the middle part of the water column and near the bottom using particle image velocimetry. These measurements showed that large-scale turbulence first arrived at the bottom in the form of a downburst of turbulent fluid. The downburst diverged at the bed and quickly spread into the surrounding non-turbulent flow. The transverse spacing between downbursts was up to several times the local still water depth. In the middle part of the water column, downbursts arrived shortly after the wave crest passed. Each downburst was followed immediately by two counter-rotating vortices. The latter must extend to the free surface since vortices cannot end in the interior of the fluid. Counter-rotating vortices were a prominent feature of the flow field at mid-depth and each vortex had a typical length scale of ½ to one water depth. It was suggested that these vortices were produced by bending and stretching of the primary spanwise vorticity generated in the wave breaking process, possibly as a result of three-dimensional deformation in the water surface. |
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