Energy Analysis of a Quasi-Two-Dimensional Friction Model for Simulation of Transient Flows in Viscoelastic Pipes

Abstract

Quasi-two-dimensional (quasi-2D) friction models have been widely investigated in transient pipe flows. In the case of viscoelastic pipes, however, the effect of different values of the Reynolds number (Re) on pressure fluctuations (which can lead to water hammer) have not been considered in detail. This study establishes a quasi-2D friction model employing an integral total energy method and investigates the work due to frictional and viscoelastic terms at different Re values. The results show that viscoelastic work (WP) and frictional work (Df) increase with an increase in Re. However, when the initial Re values are high, the Df values are much larger than the WP values. In addition, for Re < 3 × 105, the 1D model underestimated the viscoelastic terms. There was no significant difference between the two models for Re > 3 × 105. In the case of different initial Re values, the two models produced almost the same values for WP. This study provides a theoretical basis for investigating transient flow from the perspective of energy analysis.