Nonlinear Static Analysis of Deep Ocean Mining Pipe—Part II: Numerical Studies

Abstract

This part applies the modeling and solution techniques discussed in Part I to the computerized steady-state deflection analysis of deep ocean mining pipe systems. For accurate analysis, a realistic representation of drag forces along the pipe is required. This is affected by three major factors. First, in a temperature-stratified ocean, the viscosity and consequently the Reynolds number (Re) and drag coefficient vary significantly along the depth. Second, three-dimensional subsea current velocity distribution must be combined with ship velocity data and pipe configuration in the calculation of relative pipe-fluid velolcities. Finally, the drag coefficient versus Re, which varies between experiments and becomes very sensitive in the transition region, has to be properly characterized. Several cases that illustrate these parametric effects are presented for an 18,000-ft pipe modeled by three-dimensional beam elements which include coupled axial, bending and torsional deformations. The sensitivity of the results to environment characterization suggests that, for deep-ocean applications, a review of many current modeling and analysis practices is necessary.