Lagrangian modelling of fluid transients in pipelines with entrapped air

Pressure surges with large entrapped air bubbles at a dead pipe end arc difficult to simulate within an Eulerian framework, when both water/air interface movement and liquid compressibility are taken into account during the transient event Interface tracking strategies have to be used, which is often complicated and time consuming. In the paper a Lagrangian model for this problem is proposed arid solved by the second-order accurate (in space) meshless corrective smoothed particle method (CSPM) The significance of the method is that it directly approximates the Lagrangian form of the waterhammer equations on time-dependent domains with non-linear downstream boundary conditions The accuracy of the model is demonstrated by a comparison with conventional numerical solutions The model is shown to be straightforward and efficient and it is used to assess the influence of liquid compressibility on pressure surges when air pockets are present in the pipe.