Hydrodynamic forces on seabed pipelines

A new hydrodynamic force model for the prediction of forces on seabed pipelines has been verified. Comparisons of forces predicted by the new model with those measured in full-scale laboratory and field investigations demonstrate the accuracy of the model, in terms of general force characteristics, peak force values, and spectral energy content, for both regular and irregular waves, with or without superimposed currents. Pipeline motions calculated from predicted forces are in good agreement with motions calculated from measured forces. Similar comparisons using the conventional Morison equation show its deficiencies and demonstrate the considerable improvements attained by the new model. Two effects included explicitly in the new force model, related to the wake behind the pipeline and the time dependence of the force coefficients, are supported by measurements.