CFD simulation of purging process for dead-ends in water intermittent distribution systems

Abstract

In this research, the computational fluid dynamics is used to study the purging process of the inaccessible dead-end pipe subjected to saline water. A 3D multiphase Eulerian transient turbulent flow model was developed, and 48 numerical runs were conducted to examine the effect of the dead-end length, Reynolds numbers, and Total Dissolved Solids on the purging efficiency. Design charts were deduced to determine the required removal time to purge a dead-end pipe. The results revealed that the normalized removal time ranges from 35 to 460 for the studied range of variables. The removal time exponentially increases as the length of the dead-leg increases, and the removal time slightly decreases as the Reynolds numbers increases. The CFD simulation also revealed the formation of a finger-like pulse of a wave that is responsible for the mixing process (in relatively long dead-legs) and the formation of other cascades of eddies located underneath it.

Keywords

• Purging
• Intermittent
• Dead-ends
• Distribution system
• Total dissolved solid
• Time scale