On Wave-Defect Interaction in Pressurized Conduits

Pressurized conduits transporting liquids such as freshwater, storm-water, wastewater, oil and gas often experience partial blockages or leakages during their life time due to physical and/or chemical processes. In water supply, these anomalies result in about 30% of water loss and more than 30% of energy waste. Transient-based defect detection methods are highly promising, but require in-depth understanding of wave-defect-turbulence interaction in conduits. This paper develops a two-dimensional compressible flow model, based on the axial symmetry assumption, to investigate the interaction between transient waves and the flow structure in the vicinity of a leak or a blockage. An explicit Finite Volume Scheme (FVS) based on Riemann solvers is used to solve the hyperbolic part of the 2D axi-symmetric compressible Navier-Stokes equations for transient flow in a pipe. The parabolic (viscous and turbulence) part are modeled by a central differential scheme. Several boundary conditions are studied including (i) sudden closure of a valve, (ii) pulse wave and (iii) strong shock waves. Preliminary tests show that the scheme has good accuracy, efficiency and convergence characteristics. Detailed study of the scheme are ongoing and will entail comparisons with other schemes such as implicit factorized scheme and Lax-Wendroff schemes as well as experimental data. Thus far, the focus has been on laminar flows, but the physics of turbulence will be added in the near future and will involve the use of Bardina Large Eddy Simulation model