Marine Hydrodynamics Group

Research

Impact of breaking waves on a flat surface

Extreme wave impact events can cause serious damage to ships and marine structures. However, the physics of the wave impact phenomenon is poorly understood. Previous studies mostly focus on the impact of shallow-water waves on a wall with large submergence. In deep water, when the structure's lower edge is located near the water surface, the interactions between the wave and the structure's lower edge create interesting phenomena that have not been learned before. This study aims at understanding the physics of the impact of deep water breaking waves on structures near the mean water level. Several new regimes of impact phenomena are discovered and investigated in depth. New mechanisms of air entrainment during wave impact are found.

More details of this study can be found in:

Wang, A., Ikeda-Gilbert, C.M., Duncan, J.H., Lathrop, D.P., Cooker, M.J. and Fullerton, A.M., 2018, The impact of a deep-water plunging breaker on a wall with its bottom edge close to the mean water surface, Journal of Fluid Mechanics, 843, 680-721.

Wang, A., Ikeda, C. M., Drazen, D. A., Fullerton, A. M., Fu, T. and Duncan, J. H., The Impact of a Deep-Water Plunging Breaker on a Partially Submerged Cube, Proceedings of 30th Symposium on Naval Hydrodynamics, Hobart, Tasmania, Australia, November 2014.

Spray formation during controlled oblique and vertical slamming of a flat plate on a quiescent water surface

The impact between a water surface and a high-speed marine vessel, such as a planing boat, can generate a large cloud of water spray. The spray carries significant momentum and can potentially affect operation of the machineries onboard. In addition, the spray essentially becomes a visible signature of the vessel. Therefore, it is important to understand the physical mechanism of the spray formation and the characteristics of the spray evolution under controllable experimental conditions. In order to explore the physics, we investigate the slamming of a simple structure, i.e., a flat plate, with controlled motion on a quiescent water surface. A novel towing tank and two-axis carriage system are developed for this study. Two mechanisms of the spray formation are discovered. The detailed behavior of the spray under various impact conditions is revealed.

More details of this study can be found in:

Wang, A. and Duncan, J.H. , 2019, The controlled vertical impact of an inclined flat plate on a quiescent water surface, Journal of Fluid Mechanics, 879, 468–511.

Wang, A., Wang, S., Balaras, E., Conroy, D., O’Shea, T. T. and Duncan, J. H., Spray Formation during the Impact of a Flat Plate on a Water Surface, Proceedings of 31st Symposium on Naval Hydrodynamics, Monterey, California, USA, September 2016.

Fluid-structure interaction during controlled slamming of elastic plates on a water surface

During the landing of an amphibious aircraft on a water surface or the collision of a high-speed marine craft with a wave, the highly transient impact load due to the evolving hydrodynamic pressure can result in structural response of the hull. The structural deformation is transient in nature and can in turn modify the water surface motion, flow field and hydrodynamic pressure. This interaction process is exceedingly complex. This study aims at improving our physical understanding of the fluid-structure interaction during the impact of elastic plates on a water surface. A novel experimental apparatus was designed and built in order to ensure a highly controllable experimental parameter space. A thorough parametric study is performed to explore the role of important dimensionless numbers during the impact.

More details of this study can be found in:

Wang, A., Kim, H., Wong, K. P., Yu, M., Kiger, K. T. and Duncan, J. H., The Impact of a Flexible Plate on a Quiescent Water Surface, Proceedings of 33rd Symposium on Naval Hydrodynamics, Osaka, Japan, June 2020.

Wong, K.P., Kim, H.T., Wang, A., Kiger, K., Duncan, J.H. and Yu, M., 2020, High-speed interrogation of multiplexed fiber Bragg grating sensors for monitoring dynamic strain responses during a flexible plate impact on a water surface, Smart Materials and Structures, 29(12), 125021.

Wang, A., Kim, H.T., Wong, K.P., Yu, M., Kiger, K.T. and Duncan, J.H. , 2019, Spray formation and structural deformation during the oblique impact of a flexible plate on a quiescent water surface, Journal of Ship Research, 63(3), 154–164.

Wang, A., Kim, H., Wong, K. P., Yu, M., Kiger, K. T. and Duncan, J. H., The oblique impact of a flexible flat plate on a quiescent water surface, Proceedings of 32nd Symposium on Naval Hydrodynamics, Hamburg, Germany, August 2018.

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