Heave Plates – The Influence of the Plate-Diameter -to-Cylinder-Diameter Ratio, Holes, and Pitch on the Hydrodynamic Coefficients

The paper presents the results of calculations of the hydrodynamic coefficients of the heave plate using RANSECFD (Reynolds-Averaged Navier-Stokes Equations - Computational Fluid Dynamic). The obtained values were confirmed by research results available in the literature and were used to draw new conclusions on the studied issue. The calculations were performed for a wide range of Keulegan Carpenter (KC) numbers from 0.15−6.2. Plates with different plate-diameter-to-cylinder-diameter ratios (Dp/Dc = [1.4;2;4;6]) were tested, and it was found that for a KC number < 2, the greatest damping occurs for plates with a Dp/Dc ratio > 4, while for a KC number > 4.5, the opposite situation occurs and one can observe a higher damping coefficient and a lower plate diameter ratio. The influence of holes evenly distributed in a circular array in the plate on the values of hydrodynamic coefficients was investigated; for a KC number < 2, they cause an increase in the damping coefficient, but they should be used on plates with a higher plate-diameter-to-cylinder-diameter ratio. Moreover, it was shown that in the case of the combined motion of heave + pitch, the obtained values of the damping coefficient are lower than in the case of isolated motion, and it was suggested that this could be prevented by using an additional vertical plane at the edge of the plate to prevent the vortices from sliding off the plate surface.