Direct numerical simulations for multiphase flows: An overview of the multiphase code FS3D

Eisenschmidt, Kathrin; Ertl, Moritz; Gomaa, Hassan; Kieffer-Roth, Corine; Meister, Christian; Rauschenberger, Philipp; Reitzle, Martin; Schlottke, Karin

doi:10.1016/j.amc.2015.05.095

Cited by 63 publications

(31 citation statements)

References 27 publications

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“…The numerical studies in the present work are carried out with the Volume of Fluid in-house code Free Surface 3D (FS3D) originally developed by Martin Rieber [39]. Since then, FS3D has been further developed at the University of Stuttgart(see, e.g., [40] and more references given there) and at the Technical University of Darmstadt (see [9], [41][42][43][44][45][46][47]). It has been applied successfully to a variety of multiphase flow problems including falling films [41], thermocapillary effects [42], thermocapillary effects in wetting [9], (reactive) mass transfer processes at fluid interfaces [43], [44], [45], multi-component mass transfer at fluid interfaces [46] and droplet collisions at high Weber numbers [47].…”

Section: Methodsmentioning

confidence: 99%

Contact line advection using the geometrical Volume-of-Fluid method

Fricke

Marić

Bothe

2020

Journal of Computational Physics

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We consider the geometrical problem of the passive transport of a hypersurface by a prescribed velocity field in the special case where the hypersurface intersects the domain boundary. This problem emerges from the discretization of continuum models for dynamic wetting. The kinematic evolution equation for the dynamic contact angle (Fricke et al., 2019) expresses the fundamental relationship between the rate of change of the contact angle and the structure of the transporting velocity field. In the present study, it serves as a reference to verify the numerical transport of the contact angle. We employ the geometrical Volume-of-Fluid (VOF) method on a structured Cartesian grid to solve the hyperbolic transport equation for the interface in two spatial dimensions. We introduce generalizations of the Youngs and ELVIRA methods to reconstruct the interface close to the domain boundary. Both methods deliver first-order convergent results for the motion of the contact line. However, the Boundary Youngs method shows strong oscillations in the numerical contact angle that do not converge with mesh refinement. In contrast to that, the Boundary ELVIRA method provides linear convergence of the numerical contact angle transport.

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Section: Methodsmentioning

confidence: 99%

Contact line advection using the geometrical Volume-of-Fluid method

Fricke

Marić

Bothe

2020

Journal of Computational Physics

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“…FS3D is based on the Volume-ofFluid (VOF) method and solves the incompressible transient two-phase flow in 3D on a staggered Cartesian mesh. A recent overview of FS3D is given in [16]. FS3D has been validated in [15,17,18,19] for the simulation of binary droplet collisions.…”

Section: Methodsmentioning

confidence: 99%

Experimental and Computational Investigation of binary drop collisions under elevated pressure

Reitter

Liu

Breitenbach

et al. 2017

Proceedings ILASS–Europe 2017. 28th Conference on Liquid Atomization and Spray Systems

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Spray systems often operate under extreme ambient conditions like high pressure, which can have a significant influence on important spray phenomena. One of these phenomena is binary drop collisions. Such collisions, depending on the relative velocity and the impact parameter (eccentricity of the collision), can lead to drop bouncing, coalescence or breakup. This experimental and computational study is focused on the description of the phenomenon of drop bouncing, which is caused by a thin gas layer preventing the drops coalescence. To identify the main influencing parameters of this phenomenon, experiments on binary drop collisions are performed in a pressure chamber. This experimental system allows us to investigate the effect of an ambient pressure (namely the density and viscosity of the surrounding gas) on the bouncing/coalescence threshold. Keywords drop collision, breakup/coalescence, multiphase flow IntroductionUnderstanding the collisions of drops is of interest for many fields of application. They play an important role in raindrop formation [1,2] and in the modeling of fuel combustion [3,4]. Systematic experimental studies visualizing binary drop collisions provide information allowing to construct regime maps of the collision outcomes [5,6,7]. The mechanisms of bouncing, coalescence, stretching separation, reflexive separation, and shattering are observed. These mechanisms are determined by the kinetic and geometrical parameters of the collision, as well as the properties of the drop liquids and the surrounding gas. The main kinetic and geometrical parameters are defined in Figure 1, where D1 and D2 are the drop diameters and V is the relative drop velocity. B is the distance of closest approach of the drop centers, measured orthogonal to V at the instance of the collision. Dimensional analysis reveals that the collision Weber number We = V 2 D1ρ/σ, the Ohnesorge number Oh = µ/ σD1ρ, the impact parameter X = 2B/(D1 + D2) and the drop size ratio ∆D = D1/D2 determine the outcome of the collision, if the medium ambient to the colliding drops is not varied.

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“…The free surface of the liquid phase is reconstructed by the Piecewise-Linear-InterfaceConstruction (PLIC) method. Further details can be found in [11]. For the simulation of the droplet stream periodic boundary conditions in the direction of motion were used.…”

Section: Methodsmentioning

confidence: 99%

Comparison between analytical, numerical, and experimental results of grouping effects in droplet streams

Roth¹,

Gomaa²,

Livne³

et al. 2017

Proceedings ILASS–Europe 2017. 28th Conference on Liquid Atomization and Spray Systems

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Grouping of droplets was studied in monodisperse droplet streams. This very controllable system allows to study basic effects. In experiments droplet streams with monodisperse droplets were generated, however, with initially two different inter droplet spacing. A larger inter droplet spacing is followed by a little bit smaller one, which is followed by a larger one and so on. Due to this initial boundary condition groups of two droplets form, which approach each other and finally coagulate. It was found, that the velocity of the droplet approach is linearly dependent on the spacing between the droplets. This process was simulated by direct numerical simulation using the in-house code FS3D. The results of the simulations show the same linear behaviour. For larger computational domains the numerical results approach the experimental results.

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Direct numerical simulations for multiphase flows: An overview of the multiphase code FS3D

Cited by 63 publications

References 27 publications

Contact line advection using the geometrical Volume-of-Fluid method

Contact line advection using the geometrical Volume-of-Fluid method

Experimental and Computational Investigation of binary drop collisions under elevated pressure

Comparison between analytical, numerical, and experimental results of grouping effects in droplet streams

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