Glass reinforced plastic (GRP) subsea protection covers are often used to protect offshore pipelines, umbilicals and other important subsea structures from dropped objects released from offshore oil and gas and fishing activities. These covers are often subjected to waves. In the present study, flows around an oscillating GRP subsea cover and oscillatory flows around a stationary subsea cover are investigated using numerical simulations at three different KC numbers of 5, 11 and 20, which are representative for low, medium and large KC number regions. The simulations of flows around an oscillating subsea cover are used to compare with the experiments done by SINTEF Ocean (formerly MARINTEK) and validate the present numerical model. Two-dimensional (2D) simulations are carried out by solving the Unsteady Reynolds-Averaged Navier-Stokes (URANS) equations combined with the k-ω Shear Stress Transport (SST) turbulence model. It is found that the hydrodynamic forces for the two cases (flows around the oscillating cover and oscillatory flows around the stationary cover) are almost the same, which verifies that the experimental tests of subsea covers with forced motions can be used to study hydrodynamic forces on the stationary cover subjected to waves. The horizontal and vertical force coefficients and the surrounding flow fields around the covers are discussed.

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