Unsteady turbulent pipe flow due to water hammer using k–θ turbulence model

Abstract

The behaviour of unsteady turbulent pipe flow resulting from water hammer is herein numerically studied. An accurate k–θ turbulence model for two-dimensional boundary layers under adverse and favorable pressure gradients (Wilcox 1994) was applied. The results of the numerical method are in good agreement with test data obtained from both steady and unsteady turbulent pipe flows. Also, the behaviour and the structure of turbulence in unsteady turbulent pipe flows caused by water hammer were investigated. A non-dimensional parameter P as the time scale ratio of turbulence diffusion in the radial direction to the pressure wave speed introduced by Ghidaoui et al. (2002) was used. The results show that for P ≈ 1, the turbulence structure is significantly changed in the first cycle of water hammer, which is important for water quality modeling, whereas these variations are small for P ≫ 1.