Evaluation of the turbulent kinetic dissipation rate in an agitated vessel

¹ Institute of Hydrodynamics, AS CR, v.v.i., Pod Patankou 30/5, 166 12 Prague 6, Czech Republic
² Department of Process Engineering, Faculty of Mechanical Enginnering, Czech Technical University in Prague, Technicka 4, 166 07 Prague 6, Czech Republic
³ Institute for Nanomaterials, Advanced Technology and Innovation, Technical University of Liberec, Studentska 1402/2, 461 17 Liberec, Czech Republic

^a e-mail: kysela@ih.cas.cz

Published online: 12 May 2017

Abstract

The design of agitated tanks depends on operating conditions and processes for that are used for. An important parameter for the scale-up modelling is the dissipation rate of the turbulent kinetic energy. The dissipation rate is commonly assumed to be a function of the impeller power input. But this approach gives no information about distribution of the dissipation rate inside the agitated volume. In this paper the distributions of the dissipation rate inside the agitated vessels are estimated by evaluations of the CFD (Computational Fluid Dynamics). The results obtained from RANS (Reynolds Averaged Navier-Stokes equations) k-ε turbulent model and LES (Large Eddy Simulations) with Smagorinsky SGS (Sub Grid Scale) model are compared. The agitated vessels with standard geometry equipped with four baffles and stirred by either a standard Rushton turbine or a high shear impeller were investigated. The results are compared with mean dissipation rate estimated from the total impeller power input.