Investigation of turbulence behavior in pipe transient using a k–∊model

Abstract

Existing wall shear stress models and turbulence closure equations for water hammer problems are based on far-reaching assumptions in relation to the turbulence behavior during a transient event. It is often postulated that the turbulence behaves in a quasi-steady, frozen or quasi-laminar manner. Presently, the experimental or numerical data needed to investigate turbulence behavior during a transient, and to assess the often used assumptions regarding the turbulence behavior in water hammer flows, are lacking. The recent development of highly efficient numerical scheme makes it feasible to conduct numerical experiments using a k–∊model suitable for time-dependent flows. As a result, this paper develops a k–∊model for water hammer and applies it to transient pipe flows to investigate the turbulence behavior during a water hammer event and to assess the quasi-steady, frozen or quasi-laminar turbulence hypothesis

Keywords:

• Water hammer
• unsteady friction
• turbulence
• unsteady flow
• unsteadiness
• viscous losses
• scale-up formula