Fluid-structure interaction in liquid-filled piping systems

Abstract

Fluid-structure interaction in liquid-filled piping systems is modelled by extended waterhammer theory for the fluid, and beam theory for the pipes. All basic coupling mechanisms (Poisson, junction and friction coupling) are modelled. Two different solution procedures are presented. In the first procedure the governing set of equations is solved by the method of characteristics (MOC). In the second procedure the fluid equations are solved by the method of characteristics, while the pipe equations are solved by the finite element method in combination with a direct time integration scheme (MOC-FEM). The two procedures are compared with each other for a straight pipe problem. The MOC-FEM procedure is also verified against a solution procedure in which the pipe equations are solved by modal superposition. The mathematical model is validated by simulation of two experiments known fromliterature: a straight pipe experiment and an experiment with one freely moving elbow. A provisional guideline is formulated which states when interaction is of importance.