Regular and random wave pressures around large diameter submarine pipeline near ocean bed

The submarine pipeline fixed horizontally near a simulated ocean bed and parallel to the crests of the oncoming regular waves is formulated as a boundary value problem utilizing Green's second identity formulation for potential functions. Numerical results are obtained for the hydrodynamic pressures that act around the circumference of the pipeline in a finite water depth for salient pressure ports by solving the resulting integral equation. The normalized maximum pressure at each pressure port is correlated with scattering parameter, gap ratio of the pipeline from the ocean bed and depth parameter. An experimental investigation has also been carried out on the regular and random wave induced hydrodynamic pressures around a horizontal submarine pipeline placed at various elevations or gaps from the simulated ocean bed. In the random wave pressure experiments, the pipeline was subjected to random waves with Pierson- Moskowitz spectrum (P-M spectrum) at various energy levels to achieve different significant wave conditions. Numerical results of maximum hydrodynamic pressure coefficients at salient pressure ports obtained from the Green's function formulation are compared with the regular wave pressure results. The random wave hydrodynamic pressures are analysed in the frequency domain and the normalized maximum hydrodynamic pressures are evaluated using the spectral density method and through the use of least squares technique. The random wave hydrodynamic pressure results are finally compared with both the numerical and regular wave pressure results under the same pipeline and water depth conditions.