CFD-aided study on transient wave-blockage interaction in a pressurized fluid pipeline

Blockages are commonly formed in fluid pipelines such as water supply systems, which may greatly affect the internal flow states and conveyance capacities. This paper investigates the transient behavior of a pressured water pipeline with blockage under different transient wave perturbations based on the Computational Fluid Dynamics (CFD) model. To this end, a water pipeline is modeled in a 2D axisymmetric geometry with refined mesh and the blockage is modeled as a small, constricted section. Both the low and high-frequency waves (LFW and HFW), in terms of radial fundamental wave frequency of a pipeline, ∼a/R, with a being acoustic wave speed and R being pipe radius, are injected for the numerical analysis. Through this CFD model, both the axial and radial transient waves have been observed for different frequency wave injections, which are firstly validated by datasets available from former studies. After validations, the local flow characteristics, such as the velocity field, the vorticity field, and its temporal, spatial evolution in the vicinity of blockage during transient wave processes, including before and after transient wavefront passing, are elaborated and analysed in this study. The results indicate the significant influence of blockages on transient behaviors, especially under high-frequency wave conditions.