Influence of surface tension models on the hydrodynamics of wavy laminar falling films in Volume of Fluid-simulations

Albert, Christoph; Raach, Henning; Bothe, Dieter

doi:10.1016/j.ijmultiphaseflow.2012.02.011

Cited by 24 publications

(7 citation statements)

References 18 publications

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“…We found that a domain height of L y = 6 h N has a negligible effect on the dynamic behaviour of the solitary waves. This is further supported by the study of Albert et al [75] who concluded that a domain height of L y = 4 h N is sufficient. The region of the computational mesh in which the dynamically evolving gas-liquid interface is located has an equidistant resolution of 10 cells per h N , following the work of Albert et al [75].…”

Section: Setup Of the Numerical Experimentssupporting

confidence: 57%

“…This is further supported by the study of Albert et al [75] who concluded that a domain height of L y = 4 h N is sufficient. The region of the computational mesh in which the dynamically evolving gas-liquid interface is located has an equidistant resolution of 10 cells per h N , following the work of Albert et al [75]. The mesh resolution gradually increases near the substrate, with the cell center of the mesh cells closest to the substrate located at a distance of 0.0035 h N from the substrate, assuring a detailed spatial resolution of the flow separation and reversal [4,38,39] in the wave troughs observed in some of the studied cases.…”

Section: Setup Of the Numerical Experimentssupporting

confidence: 57%

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Self-similarity of solitary waves on inertia-dominated falling liquid films

et al. 2016

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We propose the first consistent scaling of solitary waves on inertia-dominated falling liquid films, which accurately accounts for the driving physical mechanisms and leads to a self-similar characterization of solitary waves. Direct numerical simulations of the entire two-phase system are conducted using a state-of-the-art finite volume framework for interfacial flows in an open domain that was previously validated against experimental film-flow data with excellent agreement. We present a detailed analysis of the wave shape and the dispersion of solitary waves on 34 different water films with Reynolds numbers Re = 20 − 120 and surface tension coefficients σ = 0.0512 − 0.072 N m −1 on substrates with inclination angles β = 19 • − 90 • . Following a detailed analysis of these cases we formulate a consistent characterization of the shape and dispersion of solitary waves, based on a newly proposed scaling derived from the Nusselt flat film solution, that unveils a self-similarity as well as the driving mechanism of solitary waves on gravity-driven liquid films. Our results demonstrate that the shape of solitary waves, i.e. height and asymmetry of the wave, is predominantly influenced by the balance of inertia and surface tension. Furthermore, we find that the dispersion of solitary waves on the inertia-dominated falling liquid films considered in this study is governed by non-linear effects and only driven by inertia, with surface tension and gravity having a negligible influence.

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Section: Setup Of the Numerical Experimentssupporting

confidence: 57%

Section: Setup Of the Numerical Experimentssupporting

confidence: 57%

Self-similarity of solitary waves on inertia-dominated falling liquid films

et al. 2016

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“…Due to imbalance in the surface tension and pressure, CSS model can also produce spurious currents [35] which has reported to be in the same order as CSF [72]. CSS model has been used to model static droplets and rising bubbles [35], but it does not provide reliable results for falling films [41].…”

Section: Publication Remarksmentioning

confidence: 99%

Comparison of Surface Tension Models for the Volume of Fluid Method

Vachaparambil

Einarsrud

2019

Processes

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With the increasing use of Computational Fluid Dynamics to investigate multiphase flow scenarios, modelling surface tension effects has been a topic of active research. A well known associated problem is the generation of spurious velocities (or currents), arising due to inaccuracies in calculations of the surface tension force. These spurious currents cause nonphysical flows which can adversely affect the predictive capability of these simulations. In this paper, we implement the Continuum Surface Force (CSF), Smoothed CSF and Sharp Surface Force (SSF) models in OpenFOAM. The models were validated for various multiphase flow scenarios for Capillary numbers of 10 − 3 –10. All the surface tension models provide reasonable agreement with benchmarking data for rising bubble simulations. Both CSF and SSF models successfully predicted the capillary rise between two parallel plates, but Smoothed CSF could not provide reliable results. The evolution of spurious current were studied for millimetre-sized stationary bubbles. The results shows that SSF and CSF models generate the least and most spurious currents, respectively. We also show that maximum time step, mesh resolution and the under-relaxation factor used in the simulations affect the magnitude of spurious currents.

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“…It should be mentioned here that the balanced continuum surface force (bCSF) model has been proven to be an effective surface tension model for restraining the 'parasitic current' in the VOF context (Popinet 2009;Boger et al 2010;Albert, Raach & Bothe 2012). However, we noticed that the bCSF model is not suitable for simulating droplet collisions in the regime of high Weber number for the following reasons:…”

Section: Governing Equationsmentioning

confidence: 87%

Numerical study of head-on droplet collisions at high Weber numbers

Liu

Bothe

2016

J. Fluid Mech.

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Head-on collisions of binary water droplets at high Weber numbers are studied by means of direct numerical simulations (DNS). We modify the lamella stabilization method of Focke & Bothe (J. Non-Newtonian Fluid Mech., vol. 166 (14), 2011, pp. 799-810), which avoids the artificial rupture of the thin lamella arising in high-energy collisions, and validate it in the regime of high Weber numbers. The simulations are conducted with and without initial disturbances and the results are compared with the experimental work of Pan et al. (Phys. Rev. E, vol. 80 (3), 2009, 036301). The influence of initial white noise disturbance on the collision dynamics is identified and good agreement between the simulation results and the experimental results is obtained when the initial noise disturbances are properly exerted. In order to include the stochastic nature of the disturbance, we conduct several simulations with white noise disturbance of same strength and average the spectrum diagram for the unstably developing rim of the collision complex. We show that the magnification of rim perturbation can be predicted by Plateau-Rayleigh theory over a long time span.

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Influence of surface tension models on the hydrodynamics of wavy laminar falling films in Volume of Fluid-simulations

Cited by 24 publications

References 18 publications

Self-similarity of solitary waves on inertia-dominated falling liquid films

Self-similarity of solitary waves on inertia-dominated falling liquid films

Comparison of Surface Tension Models for the Volume of Fluid Method

Numerical study of head-on droplet collisions at high Weber numbers

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