Load of the Small-Scale Vertical Cylinder in a Wave–Current Field

Abstract

Studies of wave–current interactions are vital for the safe design of structures. Regular waves in the presence of uniform, linear shear, and quadratic shear currents are explored by the High-Level Green–Naghdi model in this paper. The five-point central difference method is used for spatial discretization, and the fourth-order Adams predictor–corrector scheme is employed for marching in time. The domain-decomposition method is applied for the wave–current generation and absorption. The effects of currents on the wave profile and velocity field are examined under two conditions: the same velocity of currents at the still-water level and the constant flow volume of currents. Wave profiles and velocity fields demonstrate substantial differences in three types of currents owing to the diverse vertical distribution of current velocity and vorticity. Then, loads on small-scale vertical cylinders subjected to regular waves and three types of background currents with the same flow volume are investigated. The maximum load intensity and load fluctuation amplitude in uniform, linear shear, and quadratic shear currents increase sequentially. The stretched superposition method overestimates the maximum load intensity and load fluctuation amplitude in opposing currents and underestimates these values in following currents. The stretched superposition method obtains a poor approximation for strong nonlinear waves, particularly in the case of the opposing quadratic shear current.

Keywords

Wave-current interaction / Cylinder load / HLGN model / Morison equation / Regular waves

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