Cfd Model of Bubble Driven Flow in Aluminium Reduction Cells and Validation Using Piv Measurement

This paper presents a CFD modelling study of the bubble driven hydrodynamics in aluminium reduction cells. A time-averaged (steady state) bubble driven flow model has been developed using a full scale air-water model of part of an aluminium reduction cell as a test-bed. Simulated results have been compared with experimental data taken under similar conditions using Particle Image Velocimetry (PIV). Good agreement has been obtained between the CFD model and the PIV measurements, which demonstrates the validity of extending the current CFD model to study the effect of various design parameters (e.g. inter-anode gap, insertion of a slot) on bath flow in an industrial cell. Overall flow beneath the anode has been investigated in terms of streamlines calculated from both CFD simulation and PIV measurement. It was found that the water flow is very complex and is significantly affected by end channel width. NOMENCLATURE Cμр bubble induced turbulent eddy viscosity coefficient [-] CTD turbulent dispersion force coefficient [-] CCD drag force coefficient [-] d bubble diameter [m] k turbulent kinetic energy [ms] Mα interfacial momentum transfer between phases [kg ms] M Turbulent dispersion force [Nm] P pressure [Pa] SMα momentum sources due to external body forces [kg m s)] U velocity [m s] γ volume fraction [-] ε turbulent energy dissipation rate [ms] ρ density [kg m] μ dynamic viscosity [Pa·s] μt turbulent eddy viscosity [Pa·s] μtp bubble induced turbulent eddy viscosity [Pa·s] SUBSCRIPT c continuous liquid phase d dispersed gas phase t turbulence α phase, either gas (g) or water (w)