A Pressure-based Compressible-Liquid Flow Model for Computation of Instantaneous Valve Closure in Pipes

Abstract

A generalized, pressure-based compressible-liquid flow model is proposed for the isothermal low-speed flow of liquids. The flow model incorporates dedicated equations of state for liquids into the pressure-based solvers to simulate the compressible effects in liquids. The model’s capability to handle compressible liquid flow problems is evaluated against the well-established density-based water-hammer model. The isothermal flow problem of an instantaneous valve closure in an irrigation pipe and the associated flow transients are numerically solved using the proposed model by employing the Tait equation of state in conjunction with a segregated pressure-based solver algorithm. The transient flow problem is solved for a range of operating pressures, and the surge in pressure and variation of other flow properties and their interrelations are studied in detail. The proposed model could successfully capture the entire physics of the problem, including the compressible modeling of the liquid involved and could produce high accuracy numerical results. The results suggest that the pressure-based compressible-liquid flow model is a reliable and computationally inexpensive numerical tool for isothermal low-speed compressible liquid flow computations.