Hydrodynamic characteristics of an oscillating circular disk under steady in-plane current conditions

The heave motion performance of a Spar platform could be improved significantly by installing heave plates. The heave plates not only increase the vertical added mass of the platform but also provide extra damping in heave. This paper presents an investigation of the hydrodynamic characteristics of a heave plate under steady current conditions using three-dimensional direct numerical simulations. A circular disk of diameter D is forced to oscillate along its axis sinusoidally. Three aspect ratios of the disk, i.e., t(d)/D=0.1,0.05 and 0.02, are considered, respectively. The current is introduced in the plane of the disk. The influences of three parameters, the Keulegan-Carpenter number (KC), the reduced current velocity (V-r) and the aspect ratio of the disk, on the flow structures, the current drag force, the added mass and the damping of the heave plate are examined both qualitatively and quantitatively. The ranges of the KC and V, numbers considered in this study are 0 <= KC <= 1 and 0 <= V-r <= 0.25, respectively. The frequency number beta for the oscillating disk is fixed at 200. (C) 2013 Elsevier Ltd. All rights reserved.