Atomization
Primary breakup of planar coflowing gas and liquid sheets
Y. Ling, D. Fuster, G. Tryggvason, R. Scardovelli, and S. Zaleski
Gallery of Fluid Motion, 68th Annual Meeting of the APS Division of Fluid Dynamics (November 2015)
Abstract: Primary breakup of coflowing gas and liquid sheets is an important fluid dynamics problem which can been seen in many industrial applications like fuel injection. A solid understanding of spray formation through fuel injection systems is vital to improve the energy utilization efficiency and pollution control. In the present work, large-scale three-dimensional simulations are performed to investigate the breakup of coflowing gas and liquid sheets, using 2,048 processors on the supercomputer. The simulation results reveal the complex multi-scale multiphase flow features that are originally unclear. The detailed formation of the droplets through the breakup of the liquid sheet can be clearly seen from the video.
Multi-scale simulation of atomization with small drops represented by Lagrangian point-particle model
Y. Ling, S. Zaleski, and R. Scardovelli
under review by International Journal of Multiphase Flows
Abstract: Modeling and simulation of atomization is challenging due to the existence of a wide range of length scales. This multiscale nature of atomization introduces a fundamental challenge to numerical simulation. A pathway to comprehensive modeling is still to be found. The present study proposes a multiscale multiphase flow model for atomization simulations, where the large-scale interfaces are resolved by the Volume-of-Fluid (VOF) method and the small droplets by the Lagrangian Point-Particle (LPP) model. Particular attention is focused on the momentum coupling between LPP and resolved flow and the conversion between droplets represented by VOF and LPP. A series of multiphase flow problems are considered to validate the model. The results obtained by a number of simulations are compared against direct numerical simulation (DNS) results and experimental data. In particular, the model is applied to simulate the gas-assisted atomization experiment, and the numerical results are compared to the experimental measurements for a quantitative validation.
A phase inversion benchmark for multiscale multiphase flows
S. Vincent, L. Osmar, J.-L. Estivalezes, S. Zaleski, F. Auguste, W. Aniszewski, Y. Ling, T. Ménard, J. Magnaudet, J.-P. Caltagirone, A. Berlemont
under review by Journal of Computational Physics
Abstract: A series of benchmarks based on the physical situation of “phase inversion” between two incompressible liquids is presented. These benchmarks aim at progressing toward the direct numerical simulation of two-phase flows. Several CFD codes developed in French laboratories and using either Volume of Fluid or Level Set interface tracking methods are used to provide physical solutions of the benchmarks, convergence studies and code comparisons. Two typical configurations are retained, with integral scale Reynolds numbers of 7000 and 2 10^5 , respectively. The physics of the problem are probed through macroscopic quantities such as potential and kinetic energies, interfacial area, enstrophy or volume ratio of the light fluid in the top part of the cavity. In addition, scaling laws for the temporal decay of the kinetic energy are derived to check the physical relevance of the simulations. Additional test problems are also reported to estimate the influence of viscous effects in the vicinity of the interface.