Wave-enhanced interfacial transfer

Roberts, Royston M.; Chang, Hsueh‐Chia

doi:10.1016/s0009-2509(99)00391-7

Cited by 59 publications

(36 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, the connection of the film height (and flow rate) with the maximum flow velocity and the recirculation in the moving frame of reference has not been reported before. This finding is of particular interest for the optimisation of the heat and mass transport characteristics of wavy falling liquid films, which has previously been shown to be critically dependent on the characteristics of the solitary waves (Mathie et al 2013;Markides et al 2015) and with flow recirculation in the moving frame of reference typically improving the heat and mass transfer within the liquid film (Roberts & Chang 2000;Albert et al 2014). …”

mentioning

confidence: 83%

“…This zone, which appears in the main hump of the solitary waves, can considerably impact the heat and mass transport in the film due to the enhanced mixing (Roberts & Chang 2000;Albert, Marschall & Bothe 2014). Previous studies have found that the wave frequency, the inclination angle of the substrate, as well as viscous dispersion and capillary effects have a significant influence on the extent of the recirculation zone (Miyara 2000;Rohlfs & Scheid 2015).…”

mentioning

confidence: 99%

See 1 more Smart Citation

Solitary waves on falling liquid films in the inertia-dominated regime

et al. 2018

View full text Add to dashboard Cite

We offer new insights and results on the hydrodynamics of solitary waves on inertiadominated falling liquid films using a combination of experimental measurements, direct numerical simulations (DNS) and low-dimensional (LD) modelling. The DNS are shown to be in very good agreement with experimental measurements in terms of the main wave characteristics and velocity profiles over the entire range of investigated Reynolds numbers. And, surprisingly, the LD model is found to predict accurately the film height even for inertia-dominated films with high Reynolds numbers. Based on a detailed analysis of the flow field within the liquid film, the hydrodynamic mechanism responsible for a constant, or even reducing, maximum film height when the Reynolds number increases above a critical value is identified, and reasons why no flow reversal is observed underneath the wave trough above a critical Reynolds number are proposed. The saturation of the maximum film height is shown to be linked to a reduced effective inertia acting on the solitary waves as a result of flow recirculation in the main wave hump and in the moving frame of reference. Nevertheless, the velocity profile at the crest of the solitary waves remains parabolic and self-similar even after the onset of flow recirculation. The upper limit of the Reynolds number with respect to flow reversal is primarily the result of steeper solitary waves at high Reynolds numbers, which leads to larger streamwise pressure gradients that counter flow reversal. Our results should be of interest in the optimisation of the heat and mass transport characteristics of falling liquid films and can also serve as a benchmark for future model development.

show abstract

mentioning

confidence: 83%

mentioning

confidence: 99%

Solitary waves on falling liquid films in the inertia-dominated regime

et al. 2018

View full text Add to dashboard Cite

show abstract

“…This is further facilitated by the substantial reduction of the complexity of the governing equations offered by the long-wave nature of the instability. Also, due to their typically small flow rates and low pressure drops, their large contact area and their excellent heat and mass transport characteristics [15,16], falling films are utilized in a wide spectrum of engineering and technological applications, such as evaporators, heat exchangers or chemical reactor columns to name but a few.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, if inertia is sufficiently high, the maximum flow velocity of the film exceeds the phase velocity of the solitary waves, leading to a recirculation zone in the main wave hump with respect to the reference frame moving with the wave [39][40][41][42]. This flow recirculation was found to have a considerable impact on the heat and mass transport in the film due to the increased mixing [15,42,43].…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2016

View full text Add to dashboard Cite

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.

show abstract

“…For example, mass transport across a laminar falling film can increase by as much as a factor of 10 when waves appear at the interface 1 owing to the presence of a recirculation zone within the solitary waves that dominate the large-time evolution of the surface of the film. 2 Indeed, flow-assisted diffusion of heat/mass has a profound effect on a large variety of heat/mass-transport applications and understanding the enhancement mechanism is a necessary step for the development of improved transport and separation processes, crucial, e.g., in chemical engineering.…”

Section: Introductionmentioning

confidence: 99%

Introduction to the Focus Issue: Chemo-Hydrodynamic Patterns and Instabilities

Wit¹,

Eckert²,

Kalliadasis³

2012

Chaos: An Interdisciplinary Journal of Nonlinear Science

View full text Add to dashboard Cite

Pattern forming instabilities are often encountered in a wide variety of natural phenomena and technological applications, from self-organization in biological and chemical systems to oceanic or atmospheric circulation and heat and mass transport processes in engineering systems. Spatiotemporal structures are ubiquitous in hydrodynamics where numerous different convective instabilities generate pattern formation and complex spatiotemporal dynamics, which have been much studied both theoretically and experimentally. In parallel, reaction-diffusion processes provide another large family of pattern forming instabilities and spatio-temporal structures which have been analyzed for several decades. At the intersection of these two fields, "chemo-hydrodynamic patterns and instabilities" resulting from the coupling of hydrodynamic and reaction-diffusion processes have been less studied. The exploration of the new instability and symmetry-breaking scenarios emerging from the interplay between chemical reactions, diffusion and convective motions is a burgeoning field in which numerous exciting problems have emerged during the last few years. These problems range from fingering instabilities of chemical fronts and reactive fluid-fluid interfaces to the dynamics of reaction-diffusion systems in the presence of chaotic mixing. The questions to be addressed are at the interface of hydrodynamics, chemistry, engineering or environmental sciences to name a few and, as a consequence, they have started to draw the attention of several communities including both the nonlinear chemical dynamics and hydrodynamics communities. The collection of papers gathered in this Focus Issue sheds new light on a wide range of phenomena in the general area of chemo-hydrodynamic patterns and instabilities. It also serves as an overview of the current research and state-of-the-art in the field. Chemo-hydrodynamic patterns and instabilities appear in out of equilibrium systems when chemical reactions and diffusion interplay with advection or convection processes. Complex spatio-temporal evolution of concentrations can then set in due to the highly nonlinear character of the underlying dynamics. In this Focus issue, 13 articles discuss recent advances in the area of chemohydrodynamic patterns and instabilities. These articles are representative of three classes of problems in which chemo-hydrodynamic structures are commonly observed and for which simpler model systems can help unraveling key aspect of the dynamics.

show abstract

Wave-enhanced interfacial transfer

Cited by 59 publications

References 19 publications

Solitary waves on falling liquid films in the inertia-dominated regime

Solitary waves on falling liquid films in the inertia-dominated regime

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

Introduction to the Focus Issue: Chemo-Hydrodynamic Patterns and Instabilities

Contact Info

Product

Resources

About