An improved multiscale Eulerian-Lagrangian method for simulation of atomization process

The physics of atomization process involve many spatial scales, generating a wide variety of liquid inclusions of different sizes with large density and viscosity ratios between liquid and gas phases. In order to correctly capture the dynamics of these phenomena, each scale needs to be resolved with an appropriate method to ensure the conservation of physical quantities (mass, momentum) as well as the jump conditions across the liquid-gas interface. To address these problems, an original multi-scale methodology has been developed. It consists of a core coupled Level-Set/Volume-of-Fluid method (CLSVOF) for accurate capture of primary atomization, an adaptive mesh refinement technique (oct-tree AMR) to dynamically optimize the structured Cartesian mesh and a particle tracking algorithm to capture droplet dynamics. An improved Eulerian-Lagrangian coupling has been developed to ensure a smooth transition between the Eulerian and the Lagrangian modelling frameworks in the zones where they reach their respective limits of validity. The overall procedure is tested on simplified numerical tests and validated on a realistic planar liquid sheet atomization case. Results highlight the ability of the present method to reproduce the whole atomization process, from large scale instabilities to small droplet dynamics, and allow a preliminary statistical spray analysis. (C) 2017 Elsevier Ltd. All rights reserved.