Turbulent flow in stirred tanks. Part II: A two‐scale model of turbulence

Abstract

Abstract The two‐scale turbulence concept is recommended for modeling the turbulence in a baffled vessel equipped with a Rushton‐type turbine impeller. A three‐equation isotropic turbulence model is proposed that employs the balance equations for: the kinetic energy of the large scale vortices; the kinetic energy of the inertial subrange eddies; and the dissipation rate of the small‐scale turbulence. The energy transfer rate from the large‐scale vortices is prescribed algebraically. Flow patterns are modeled by solving the transport equations for vorticity, stream function, and tangential momentum. The Reynolds stresses are modeled by means of the effective viscosity, based on the three‐equation model of turbulence. The calculated profiles of the mean velocity at the tank wall agree with experimental data obtained in the same system by means of a Pitot tube.