Numerical study on the force distribution on cylindrical structure by internal solitary wave and its prediction with Morison equation

The forces by internal solitary wave on cylinder structure are computed to understand their temporal distribution on different cylinder sections. The results confirm that the total forces could be decomposed into inertial and drag components approximately. Three empirical coefficients determination methods which are referred to as global coefficients, local coefficients, and coefficients based on regression models, are tested to analyze the dependence of the inertial and drag coefficients on the velocity field characteristics. The results show that the layer dependent empirical coefficients could improve the performances of Morison equation in the upper and lower layers, while its advantage in layers close to density interface is not obvious, which is related to the large vertical velocity components in this region. The regression models are derived by fitting selected coefficients samples, and the empirical coefficients predicted are very close to the results by Sarpkaya (1976) for oscillating flows in the same Reynolds number range.