Wave impact loads: the role of the Flip-Through.

The impact of waves upon a vertical, rigid wall during sloshing is analyzed with specific focus on the modes that lead to the generation of a flip-through [M. J. Cooker and D. H. Peregrine, “A model for breaking wave impact pressures,” in Proceedings of the 22nd International Conference on Coastal Engineering (ASCE, Delft, 1990), Vol. 2, pp. 1473–1486]. Experimental data, based on a time-resolved particle image velocimetry technique and on a novel free-surface tracking method [M. Miozzi, “Particle image velocimetry using feature tracking and Delaunay tessellation,” in Proceedings of the 12th International Symposium on Applications of Laser Techniques to Fluid Mechanics (2004)], are used to characterize the details of the flip-through dynamics while wave loads are computed by integrating the experimental pressure distributions. Three different flip-through modes are observed and studied in dependence on the amount and modes of air trapping. No air entrapment characterizes a “mode a flip-through,” engulfment of a single, well-formed air bubble is typical of a “mode b” event, while the generation of a fine-scale air-water mixing occurs for a “mode c” event. Upward accelerations of the flip-through jet exceeding 1500 g have been measured and the generation/collapse process of a small air cavity is described in conjunction with the available pressure time histories. Predictions of the vertical pressure distributions made with the pressure-impulse model of Cooker and Peregrine [M. J. Cooker and D. H. Peregrine, “Pressure-impulse theory for liquid impact problems,” J. Fluid Mech. 297, 193 (1995)] show good agreement with the experimental data.