Numerical simulation of oscillatory falling liquid film flows

Kunugi, Tomoaki; Kino, Chiaki

doi:10.1016/s0920-3796(03)00007-3

Cited by 20 publications

(5 citation statements)

References 4 publications

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“…showed that the heat transfer coefficient h (obtained from numerical simulation) exhibits local maxima at the respective capillary minima, the most significant increase in h occurring at the first capillary minimum. Similar numerical results were obtained by Miyara (2001), Kunugi and Kino (2003) and , while experimental confirmation was provided by Schagen et al (2006). obtained similar results from their 3-dimensional simulations, reporting a substantial increase of h at the first capillary minimum.…”

Section: Introductionsupporting

confidence: 84%

Flow Separation in Falling Liquid Films

Dietze¹,

Kneer²

2011

Frontiers in Heat and Mass Transfer

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Despite the use of liquid films in a wide variety of technical applications involving heat and mass transfer (e.g. nuclear reactors, cooling towers and gas turbines), where they often play an important role, the underlying momentum and heat transport processes within these thin liquid layers remain to be fully elucidated. In particular, this applies to the influence that surface waves, developing due to the film's natural instability, exert on the mentioned processes. In this context, it has been suggested by several experimental and numerical observations that momentum and heat transfer in the capillary wave region (which precedes large surface waves) undergo drastic variations. Indeed, some results have indicated the occurrence of upward flow (i.e. opposed to the gravitational acceleration) in this region. Moreover, evidence of a large increase in wall-side and interfacial transfer coefficients has also been noted. Recently, the authors have established that flow separation takes place in the capillary wave region of 2-and 3-dimensional laminar falling liquid films, partially explaining the above mentioned observations. They showed that the strong change in curvature of the liquid-gas interface in this region causes an adverse pressure gradient (due to the action of surface tension forces) sufficiently large to induce flow detachment from the wall. In the present paper, an in-depth experimental and numerical investigation of this phenomenon in terms of its kinematics and governing dynamics as well as its effect on heat transfer for two different 2-dimensional flow conditions is presented. Experimentally, velocity measurements (using Laser Doppler Velocimetry and Particle Image Velocimetry) and film thickness measurements (using a Confocal Chromatic Imaging technique) were performed in a specifically designed optical test setup. On the numerical side, simulations of the full Navier-Stokes equations as well as the energy equation using the Volume of Fluid (VOF) method were performed. In addition to these investigations, the numerical simulation of a 3-dimensional vertically falling water film, for flow conditions studied in a previous experimental contribution to the literature, was performed. Based on these data, the characteristics of capillary flow separation in the presence of 3-dimensional surface waves were studied. Results show that flow separation takes place in several areas of the resulting complex 3-dimensional capillary wave region, developing multiple separation zones in the shape of vortex tubes. In addition, spanwise flow and an associated eddy induced by the same governing mechanism are shown to occur in this region. This could explain the strong intensification of transfer to 3-dimensional liquid films.

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Section: Introductionsupporting

confidence: 84%

Flow Separation in Falling Liquid Films

Dietze¹,

Kneer²

2011

Frontiers in Heat and Mass Transfer

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“…Davis thinks that there is a Bragg resonance between the surface waves and the ripple, which is associated with the reflection of incident wave energy [9]. Tomoaki researched the oscillatory falling liquid film flows, the results showed the heat transfer of the falling liquid film flow can be controlled by the artificial oscillation of the film flow [10]. The unique feature of the film instability is that the surface tension, the gravity, the viscous force, and inertial force all play equally important roles.…”

Section: Introductionmentioning

confidence: 99%

The Surface Characteristic of the Film Flow under Different Surface Tension and Uneven Bottom

Liu

2012

AMM

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In the paper, with the change of the relation between the Bond numbers and 1/3, the different control equations with different dispersion item was obtained for the surface wave of film under uneven bottom. The equation under tension and bottom was reduced from the potential flow theory with the little parameter perturbation technique, and then was solved by using the numerical method. The waterfall of the surface wave was simulated with Matlab software. The results show that different surface tension and different bottom has different effect on the film surface.

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“…Akio Miyara studied the interfacial wave behavior and flow characteristics of falling liquid film on a vertical wall, in which the algorithm is based on MAC method [13]. Tomoaki Kunugi and Chiaki Kino researched the oscillatory falling liquid film flows, the results showed the heat transfer of the falling liquid film flow can be controlled by the artificial oscillation of the film flow [14]. The unique feature of the film instability is that the surface tension, the gravity, the viscous force, different flow state, and inertial force all play equally important roles.…”

Section: Introductionmentioning

confidence: 99%

Numerical Research for the Film Surface Wave with the Different Flow Case

Chen

Liu

2011

AMR

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The effects of different flow case, including resonant case, supercritical case and subcritical case, on the nonlinear surface waves of film with uneven bottom were analyzed. Derived from the potential flow theory, the fKdV equation on the nonlinear surface wave was obtained by the little parameter perturbation technique. The simulation was made by pseudo-spectral method, and the waterfall plot of the surface wave was illustrated with Matlab program. The flow, incompressible and inviscid, of which the surface tension and uneven boundary is considered. The results comprehensive surface waves located on the film is very different among the three flow cases.

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Numerical simulation of oscillatory falling liquid film flows

Cited by 20 publications

References 4 publications

Flow Separation in Falling Liquid Films

Flow Separation in Falling Liquid Films

The Surface Characteristic of the Film Flow under Different Surface Tension and Uneven Bottom

Numerical Research for the Film Surface Wave with the Different Flow Case

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