Abstract
CFD modelling of two-phase liquid-liquid flow in a SMX static mixer The paper provides an overview of the application of Computational Fluid Dynamics tools for predicting transport processes in two-phase flow in a SMX static mixer. The overview is achieved by taking a brief look at factors: mesh generation, development of sub-models, post-processing including validation and quantitative verification of CFD results with experimental data. Two types of numerical approach were used in the simulations: the Reynolds averaged Navier-Stokes in the steady-state mode with the standard k-??turbulence model and Large Eddy Simulations in the unsteady mode. Both CFD techniques were applied to calculate flow velocities, pressure drop and homogenisation level in a SMX static mixer of the liquid-liquid mixture. The steady state drop size distribution was obtained by implementation procedure containing the population balance equation, where transport equations for the moments of the drop size distribution are solved and the closure problem is overcome by using the Quadrature Method of Moments.
Highlights
Fluid flow through a SMX static mixer and liquid-liquid dispersion analysis are common in chemical engineering
The comparisons of the z-direction local vorticity and the local mixture helicity in the SMX static mixer predicted by Large Eddy Simulation (LES) and Reynolds averaged Navier-Stokes (RANS) are shown in Figures 3 and 4
Grosz-Roll[12] and Cybulski and Werner[13] carried out experiments for the SMX static mixer in laminar flow or for the SMV static mixer in turbulent flow[12], but they considered systems of the ratio Lm/D around 11, while we considered Lm/D=14.3
Summary
Fluid flow through a SMX static mixer and liquid-liquid dispersion analysis are common in chemical engineering. It can be concluded that the prediction of velocity field, pressure drop, concentration and drop size distribution in the SMX static mixer for low and intermediate Reynolds number has been accurately analyzed using standard CFD solvers and a fine grid resolution[20,21]. The step in the numerical analysis comprised computation of the drop breakage within the SMX static mixer given by the population balance equation. The Sauter mean diameter used for the SMX mixer was constant 1.005 [mm] for Re=1000030 both in the RANS and LES modelling, while when the drop population balance equations in the QMOM version were solved, the following estimated initial values of the six moments were used: m0=1.88.109 [1/m3], m1=1.89.106 [1/m2],. The momentum transfer iterations were performed with the default numerical parameters available in the code and the normalized residual sum of 10-6
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