Hydrodynamic damping of solid and perforated heave plates oscillating at low KC number based on experimental data: A review. (1st June 2022)

• Record Type: Journal Article
• Authors: Ezoji, Mojtaba; Shabakhty, Naser; Tao, Longbin
• Is Part Of: Ocean engineering. Volume 253(2022)
• Publication Date: 2022-06-01
• Subjects: Solid heave plate -- Perforated heave plates -- Viscous damping; Ocean engineering -- Periodicals; Ocean engineering; Periodicals; 620.4162
• DOI: 10.1016/j.oceaneng.2022.111247
• Languages: English
• ISSNs: 0029-8018

Abstract

Abstract: Heave plates exert a unique influence on the motions of marine structures floating in seas or oceans. Due to their low thickness and sharp edges, the hydrodynamic performance of these plates is influenced by such physical and oscillatory parameters as the Keulegan–Carpenter (KC) number, frequency, perforation ratio, cavity arrangement, cavity size, plate thickness, and proximity to free surface and sea floor. The present study tries to present an understanding of the hydrodynamic behavior of solid and perforated heave plates at low KC number by analyzing the flow regime and the related equations. Assessments have shown that at low a KC number, where the amplitude of oscillations is limited, the viscous damping derived from flow separation is proportionate to the area of the edges. Therefore, compared to solid plates, increasing the lengths of the edges by creating inner edges increases the viscous damping of these plates. Hence, in addition to solid plates, the performance of perforated plates has also been evaluated in this study. In this study, in addition to the other parameters, a new parameter – i.e., plate edges area-to-plate area ratio (Re/a) – has been used as basis to compare the results. Also, by investigating the experimental data of different researchers, a comprehensive study of the performance of heave plates will be provided. Finally, the parameters necessary for a better understanding of the hydrodynamic performance of these plates and the damping caused by the oscillations of a floating body in fluid will also be discussed. Highlights: Comprehensive review of the hydrodynamic behavior of solid and perforated heave plates by analyzing the flow regime and the related equations. The viscosity damping derived from flow separation is proportionate to the length of the edges. A new parameter –plate edge length-to-plate area ratio– has been used as basis to compare the results. Assessing models with different scales has shown that they have more or less similar hydrodynamic behaviors. Choosing appropriate values for perforation ratio and oscillation frequency can maximize the damping coefficient in different ocean conditions.