Sensitivity of VOF simulations of the liquid jet breakup to physical and numerical parameters

Großhans, Holger; Movaghar, Amirreza; Cao, Le; Oevermann, Michael; Szász, Róbert-Zoltán; Fuchs, László

doi:10.1016/j.compfluid.2016.06.018

Cited by 40 publications

(24 citation statements)

References 60 publications

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“…The case is discretely solved by utilizing the three convection schemes The appearance of Kelvin-Helmholtz (KH) instabilities at the interface is due to the competition between shear forces, caused by the velocity difference of the two streams, and capillary stresses. This is in agreement with the reference work [25] and other studies regarding two-phase coaxial jets [5,43,44]. The KH instabilities are responsible for triggering the jet transition from laminar to turbulent regime.…”

Section: Validation and Resultssupporting

confidence: 92%

A low-dissipation convection scheme for the stable discretization of turbulent interfacial flow

et al. 2017

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© 2017. This version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/This paper analyzes a low-dissipation discretization for the resolution of immiscible, incompressible multiphase flow by means of interface-capturing schemes. The discretization is built on a three-dimensional, unstructured finite-volume framework and aims at minimizing the differences in kinetic energy preservation with respect to the continuous governing equations. This property plays a fundamental role in the case of flows presenting significant levels of turbulence. At the same time, the hybrid form of the convective operator proposed in this work incorporates localized low-dispersion characteristics to limit the growth of spurious flow solutions. The low-dissipation discrete framework is presented in detail and, in order to expose the advantages with respect to commonly used methodologies, its conservation properties and accuracy are extensively studied, both theoretically and numerically. Numerical tests are performed by considering a three-dimensional vortex, an exact sinusoidal function, and a spherical drop subjected to surface tension forces in equilibrium and immersed in a swirling velocity field. Finally, the turbulent atomization of a liquid-gas jet is numerically analyzed to further assess the capabilities of the method.Peer ReviewedPostprint (author's final draft

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Section: Validation and Resultssupporting

confidence: 92%

A low-dissipation convection scheme for the stable discretization of turbulent interfacial flow

et al. 2017

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“…Kelvin-Helmholtz instability is commonly seen in JICF due to the occurrence of shear between the interface of the two fluids, as previously reported by Herrmann [17] and Grosshans et al [8]. The Kelvin-Helmholtz instability naturally occurs when two layers of fluids move with different speed lying close to each other.…”

Section: Turbulence In Jicfsupporting

confidence: 57%

“…However, there is a lack of relevant information related to the breakup mechanisms and spray formation. For example, the influence of fluid properties on the liquid jet breakup is yet few understood [8]. In addition, the detailed structure within the main spray region is not yet fully understood [9].…”

Section: Liquid Breakup and Spray Formationmentioning

confidence: 99%

“…According to Bravo [10], a full understanding of the primary atomization process has not been achieved for several reasons, including difficulties in visualizing the main dense region. According to Grosshans et al [8], due to the large number of droplets, experimental measurements in these flow regions may be very challenging. Regarding droplet size distributions in dense sprays, results are mainly blurred.…”

Section: Liquid Breakup and Spray Formationmentioning

confidence: 99%

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Primary atomization of a turbulent liquid jet in crossflow: a comparison between VOF and FGVT methods

Duarte

Barbi

Villar

et al. 2020

J Braz. Soc. Mech. Sci. Eng.

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The primary atomization of a turbulent liquid jet in crossflow was investigated using a mathematical, numerical and computational model. A comparison between the standard volume of fluid (VOF) method and the fine grid volume tracking (FGVT) method was reported. The FGVT method advects the interface between two fluids using a finer grid than the employed by the standard VOF method, and according to the literature, it provides a better interface resolution. Simulations were performed using adaptive mesh refinement in a three-dimensional domain subjected to gravitational field using the in-house code MFSim. The flow was modeled using an Eulerian-Lagrangian approach to capture the interface. The interface was tracked initially with VOF or FGVT methods until the initial breakup. Broken off, small-scale nearly spherical drops were transferred into the Lagrangian point particle description. Column breakup and shear breakup modes were observed on the liquid jet. Drops were small as one-hundredth the size of the injector diameter. The model was validated against experimental correlations for the liquid jet column trajectory, and the droplet size distribution was compared to a previous numerical study from the literature. In addition, the breakup mechanisms predicted were qualitatively compared to those in previous reports. The results of the liquid column trajectory from the simulations performed presented low differences with the literature for both methods tested. According to the numerical results obtained from the computational simulations, the liquid column trajectory was well captured and the droplet size distribution was similar to the literature; however, the FGVT method provided higher accuracy compared to VOF method. The two main breakup modes were identified, namely the column breakup with Kelvin-Helmholtz instabilities and the surface breakup with the formation of multiple ligaments which later lead to droplet formation. The FGVT method provided a more detailed interface contour and improved the number of droplets converted from the Eulerian to the Lagrangian approach compared to the standard VOF method. On the other hand, the FGVT method presented relatively higher computational costs compared to VOF. Therefore, the FGVT method presented a higher interface quality and allowed a larger number of droplet conversion to the Lagrangian approach compared to the VOF method, even though the simulation run time using VOF was lower than with FGVT.

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“…Several a-priori studies have shown that these terms, appearing due to the filtering across the interface, are not negligible (Toutant et al, 2008;Vincent et al, 2008;Larocque et al, 2010;Chesnel et al, 2011b;Klein et al, 2019) which suggests that the accuracy of multiphase flow LES depends on their proper modelling. Early LES studies of liquid atomization mostly neglected them (de Villiers et al, 2004;Bianchi et al, 2007;Grosshans et al, 2016), but the work by Chesnel et al (2011b) and Herrmann (2013) suggested that there is a beneficial effect when SGS interface structures and their interaction with the flow are properly taken into account. Modelling of the additional terms is difficult because standard modelling assumptions do not necessarily apply (Sagaut and Germano, 2005).…”

Section: Introductionmentioning

confidence: 99%

Large eddy simulation of multiphase flows using the volume of fluid method: Part 2—A-posteriori analysis of liquid jet atomization

Ketterl

Reißmann

Klein

2019

Exp. Comput. Multiph. Flow

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Multiphase flows with two or more immiscible liquids, separated by a sharp interface with surface tension, occur in a large variety of environmental and industrial flow problems. The ability to accurately predict such flows has implications for safety, economy, and ecology. As a scale resolving technique, large eddy simulation (LES) is a turbulence model that has the potential to describe such flows with good accuracy. However, during the filtering process of the two-phase flow equations, several unclosed terms appear that are unknown from single-phase flow and their modelling is not yet standardized in the open literature. In this paper, the unknown terms are systematically analyzed based on a-posteriori LES and comparison with a direct numerical simulation (DNS) database. It is shown that the closures for each unknown term strongly interact with the other terms and as well with the numerical scheme. Therefore, only a modelling strategy consisting of a complete set of sub-models and numerical discretization can be identified, rather than individual optimal models. Several promising alternatives are identified and discussed, based on existing and newly developed turbulence and interfacial subgrid scale (SGS) closures.

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Sensitivity of VOF simulations of the liquid jet breakup to physical and numerical parameters

Cited by 40 publications

References 60 publications

A low-dissipation convection scheme for the stable discretization of turbulent interfacial flow

A low-dissipation convection scheme for the stable discretization of turbulent interfacial flow

Primary atomization of a turbulent liquid jet in crossflow: a comparison between VOF and FGVT methods

Large eddy simulation of multiphase flows using the volume of fluid method: Part 2—A-posteriori analysis of liquid jet atomization

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