An Efficient Estimation of Fluid–Structure Interaction in Blocked L-shaped Pipelines

The vibration of bends or T-sections excites flexural modes, which require a numerically complex fourth-order differential term in the fluid–structure interaction (FSI) simulation. This paper presents an efficient approximate approach as an alternative to the full simulation of the bending vibration equations. The flexural stiffness of one pipe is lumped at the boundary of the other pipe to eliminate the corresponding problematic differential equation describing lateral vibration. FSI results obtained by the full simulation of the lateral vibration equations are compared with the corresponding proposed approach for intact and blocked L-shaped pipes. The results reveal that the approximate simulation is approximately ten times faster than the full simulation and easier to program. It can simulate different pipe lengths, valve closure times, pipe diameter to wall thickness ratios, blockage lengths, blockage ratios, and blockage locations with sufficient accuracy. Therefore, it can be a promising alternative for the full simulation of blocked pipe systems. As observed in several studies, junction vibration can generate significant signatures on the transient pressure response, which are similar to those of pipe defects and flow blockages meaning that it is important for the simulation model to be able to reflect these dynamics in order to be able to be reliably used to interpret the measured signal. The approximate model can lead to an accurate and simple junction-coupling transient solver for defect detection in pipeline systems without the inconvenience of solving the equation of lateral motion where the FSI effect is not negligible.