Fluid-structure interaction in thin laminated cylindrical pipes during water hammer

Composite pipes with unidirectional fiber-reinforced layers at different fiber orientations are used in many industrial applications. When they carry pressurized fluids, water hammer may occur during any rapid change in the momentum of the fluid flow. Water hammer produces a travelling pressure wave and causes pipe vibration. This vibration, in turn, affects the water hammer so that fluid-structure interaction may play an important role in the pipe design calculations. In this paper, governing equations for the fluid-structure interaction of water hammer in thin laminated pipes were derived by assuming longitudinal vibration of the pipe. The resulting system of partial differential equations (PDEs) was solved numerically using an implicit least squares technique. The method uses radial basis functions locally in function approximations leading to a sparse and symmetric coefficient matrix. Two problems were solved using the proposed numerical method and the effect of the number of layers on the travelling pressure wave characteristics was investigated.