Primary atomization of liquid jets: Identification and investigation of droplets at the instant of their formation using direct numerical simulation

Trautner, Elias; Haßlberger, Josef; Ketterl, S.; Klein, Markus

doi:10.1016/j.ijmultiphaseflow.2022.104360

Cited by 3 publications

(1 citation statement)

References 76 publications

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“…The above mathematical model has been established during the last decade and has been applied to a large number of two-phase flow problems in the literature [29][30][31][32][33][34][35]. In addition, the recent paper by the code developers [23], includes a wide variety of wellknown test cases such as Poiseuille flow, capillary waves, oscillating droplets and bubbles, and a falling raindrop.…”

Section: Governing Equations and Flow Solvermentioning

confidence: 99%

Effect of the Density Ratio on Emulsions and Their Segregation: A Direct Numerical Simulation Study

et al. 2023

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Using direct numerical simulation (DNS) in combination with the volume of fluid method (VoF), we investigate the influence of the density ratio between the carrier and dispersed phase on emulsions, where the baseline simulation approximately corresponds to the ratio of water-in-gasoline emulsions. For this purpose, homogeneous isotropic turbulence (HIT) is generated using a linear forcing method, enhanced by a proportional–integral–derivative (PID) controller, ensuring a constant turbulent kinetic energy (TKE) for two-phase flows, where the TKE balance equation contains an additional term due to surface tension. Then, the forcing is stopped, and gravitational acceleration is activated. The proposed computational setup represents a unique and well-controlled configuration to study emulsification and segregation. We consider four different density ratios, which are applied in industrial processes, to investigate the influence of the density ratio on the statistically steady state of the emulsions, and their segregation under decaying turbulence and constant gravitational acceleration. At the statistically steady state, we hold the turbulence constant and study the effects of the density ratio ρd/ρc, on the interface area, the Sauter mean diameter (SMD), and the statistical droplet size distribution. We find that all are affected by the density ratio, and we observe a relation between the SMD and ρd/ρc. Furthermore, we assume a dependence of the critical Weber number on the density ratio. In the second part of our work, we study the segregation process. To this end, we consider the change in the center of mass of the disperse phase and the energy release, to analyze the dependence of segregation on the density difference Δρ/ρd. We show that segregation scales with the density difference and the droplet size, and a segregation time scale has been suggested that collapses the height of the center of mass for different density ratios.

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Section: Governing Equations and Flow Solvermentioning

confidence: 99%

Effect of the Density Ratio on Emulsions and Their Segregation: A Direct Numerical Simulation Study

et al. 2023

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Toward large eddy simulation of shear-thinning liquid jets: A priori analysis of subgrid scale closures for multiphase flows

Abdelsayed,

Hasslberger,

Ertl

et al. 2024

Physics of Fluids

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While direct numerical simulation (DNS) of multiphase flows has been the focus of many research investigations in recent years, large eddy simulation (LES) of multiphase flows remains a challenge. There is no standardized set of governing equations for multiphase LES. Different approaches and formulations have been discussed in the literature, each with its own advantages and disadvantages. In this paper, the conventional (non-weighted) filtering approach is compared with the density-weighted Favre filtering method by evaluating the subgrid scale (SGS) energy transfer for a simple test case of a shear-thinning droplet in air. The findings reveal that, unlike the Favre filtering approach, the conventional filtering method results in a notable amount of nonphysical backward scatter in the flow. Based on these results, the Favre filtering method appears preferable and is applied to the a priori analysis of shear-thinning liquid jets, where the viscosity has been modeled using the Carreau–Yasuda model. First, by explicitly filtering existing DNS data of shear-thinning jet breakup into stagnant air, the order of magnitude of different SGS terms is evaluated using the Favre filtering method. Consistent with earlier studies on Newtonian jets, the present study indicates that the diffusive term remains negligible, while the convective term plays a dominant role. Functional and structural models for the closure of the convective SGS term are assessed by means of a correlation analysis and an order of magnitude study. Existing structural models provide good results for both Newtonian and shear-thinning cases. Promising a posteriori model candidates are discussed.

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Droplet Velocity and Size Characteristics During Industrial Furnace Dual Fluid Atomizer Biodiesel Swirl Atomization

Ma,

li,

Wang

et al. 2023

Preprint

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Primary atomization of liquid jets: Identification and investigation of droplets at the instant of their formation using direct numerical simulation

Cited by 3 publications

References 76 publications

Effect of the Density Ratio on Emulsions and Their Segregation: A Direct Numerical Simulation Study

Effect of the Density Ratio on Emulsions and Their Segregation: A Direct Numerical Simulation Study

Toward large eddy simulation of shear-thinning liquid jets: A priori analysis of subgrid scale closures for multiphase flows

Droplet Velocity and Size Characteristics During Industrial Furnace Dual Fluid Atomizer Biodiesel Swirl Atomization

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