Large Eddy Simulation of distillation sieve tray hydrodynamics - a Volume-of-Fluid (VOF) approach

A Large Eddy Simulation (LES) model is utilised to analyse the hydrodynamics of an industrial-scale distillation sieve tray. Three-dimensional two-phase flow of gas and liquid is considered in which the flow was modelled based on the concept of phasic volume defined in the Volume-of-Fluid (VOF) multiphase model. All governing equations including surface tension and wall adhesion are solved simultaneously using the commercial FLUENT code. The computational domain and operating conditions were adapted from experimental study where liquid velocity profiles, clear liquid height, and flow patterns were among the important quantities monitored. This work focuses on the improvement of the accuracy relative to experimental data with our new model over other existing Reynolds-Averaged Navier-Stokes (RANS) based models. Gas-liquid interfaces and the existence of froth regime are clearly visualised via the VOF model. The predicted quantities are found out to be in very good agreement with experimental data having discrepancies of less than 1.0%. Mesh resolutions above the bubbling area is identified as the key factor in accurate modelling of sieve tray hydrodynamics. The present model can be utilised with high confidence as the basis for the optimisation of sieve tray mechanical design.