Effect of Hydrodynamic Forces on Spanning Pipes

In this study the spanning behavior of submerged pipes are analyzed and discussed. In the order to do so the limits of Reynolds number less than 3.5 105 and Keulegan Carpenter number is between 4 and 7acsepted as limitation of the work. Under this limitation it is clear that even at low orbital velocities momentum initiates at intermediate depth. Therefore the current velocity and orbital velocity at intermediate depth are computed to determine the in-line and cross-flow net forces on spanning submarine pipe. These forces were useful while calculating the maximum deflections and moment that occurs at the mid length of the pin supported pipes. The magnitude of yield stress of HDPE pipes are then compared with the maximum bending stress of the pipe in the order to calculate the critical spanning length of different HDPE pipe diameter and thicknesses. The results show similarity with the model which was generated for spanning steel pipes. This deflection calculated for simply support pipes and also modelled in the ANSYS software. Keywords: Vortex, Drag force, Inertia force, HDPE, Span length.