Large–eddy simulation in a Sonolator high–pressure homogeniser

Abstract

This paper examines the fluid dynamics of a pilot–scale high–pressure homogeniser using large–eddy simulation. The mixer consists of a non–planar elliptic jet released into a confined cylindrical chamber. The simulated results are validated by comparing mean quantities with published experimental data. The evolution of the shear layers in the jet near–field shows a localised region of high turbulent energy dissipation rate in the major plane, whereas in the minor plane the dissipation rate is of smaller magnitude and spreads over a wider region. The validity of the turbulence isotropy assumption, typically made in dispersed–phase modelling, is examined. Energy spectra exhibit an amplification close to the nozzle at frequencies associated with vortex shedding. Kolmogorovs classical 2/3 scaling in the second–order structure functions is found to be overshadowed by vortex shedding, resulting in steeper slopes in the jet near–field, where the rate of energy dissipation assumes the largest value in the mixer.