Stability of a rivulet flowing in a microchannel

Herrada, Miguel A.; Mohamed, Ahmed; Montanero, J. M.; Gañán‐Calvo, Alfonso M.

doi:10.1016/j.ijmultiphaseflow.2014.10.012

Cited by 16 publications

(8 citation statements)

References 25 publications

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“…as α → π − ; therefore the thin-film approximation will break down sufficiently near to α = π. At the middle of the cylinder (α = π/2), where the azimuthal component of gravity is significant but the normal component is zero, the rivulet has finite width and thickness given by (29). As Fig.…”

Section: A Flow Around a Large Horizontal Cylindermentioning

confidence: 99%

“…19 In addition, similarity solutions have been obtained and analysed for steady 20,21 and unsteady 22 flows of non-uniform rivulets. There has also been considerable work on the stability of rivulet flow, [23][24][25][26][27][28][29] on waves on rivulets, [30][31][32][33] and on rivulet braiding and meandering. [34][35][36][37][38] However, despite the widespread occurrence of non-Newtonian rheology in many of the practical occurrences of rivulet flow, there has been surprisingly little theoretical work on rivulet flow of non-Newtonian fluids.…”

Section: Introductionmentioning

confidence: 99%

“…Plot of the semi-width a given by(29) as a function ofQ in the special case of a vertical substrate (α = π/2), for N = 1/100, 1/10, 1, and 10. The dotted line shows the asymptotic solution a = 2 in the limit N → 0 + , and the dashed line shows the asymptotic solution a = (15Q/2) 1/3 in the limit N → ∞.…”

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confidence: 99%

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A rivulet of a power-law fluid with constant contact angle draining down a slowly varying substrate

2015

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Locally unidirectional steady gravity-driven flow of a thin rivulet of a power-law fluid with prescribed volume flux down a locally planar substrate is considered. First the solution for unidirectional flow of a uniform rivulet down a planar substrate is obtained, and then it is used to obtain the solution for a slowly varying rivulet with prescribed constant (nonzero) contact angle down a slowly varying substrate, specifically flow in the azimuthal direction around the outside of a large horizontal circular cylinder. The solution is shown to depend strongly on the value of the power-law index of the fluid. For example, a rivulet of strongly shear-thinning fluid "self-channels" its flow down a narrow central channel between two "levees" of slowly moving fluid that form at its sides, and in the central channel there is a "plug-like" flow except in a boundary layer near the substrate. On the other hand, in a rivulet of a strongly shear-thickening fluid the velocity profile is linear except in a boundary layer near the free surface. Another notable qualitative departure from Newtonian behaviour is that, whereas the mass of a rivulet of a Newtonian or a shear-thinning fluid is theoretically infinite, the mass of a rivulet of a shear-thickening fluid is finite

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Section: A Flow Around a Large Horizontal Cylindermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A rivulet of a power-law fluid with constant contact angle draining down a slowly varying substrate

2015

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“…These identifiers will be used as subscripts in Eqs. (5) to (8). To apply the Richardson extrapolation, the results need to fall within the asymptotic range of convergence.…”

Section: Numerical Approach and Grid Independence Checkmentioning

confidence: 99%

“…The hydrodynamics of rivulets has been an open problem in recent decades, with applications in absorption, heat exchange, microfluidics, and distillation . The flow of a liquid phase running down a solid substrate has been studied in the past using both experimental and computational methods, usually with the purpose of optimizing the gas‐liquid interface by varying the physical properties of the liquid . Less attention, however, has been directed towards the fundamentals of the instabilities inherent to such flows; namely, meandering and braiding.…”

Section: Introductionmentioning

confidence: 99%

Numerical Modelling of Braiding and Meandering Instabilities in Gravity‐Driven Liquid Rivulets

Sebastia‐Saez

Reina

Arellano‐García

2017

Chemie Ingenieur Technik

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Rivulet instabilities appear in many engineering applications. In absorption equipment, they affect the interface area available for mass transfer, and thus, reducing the efficiency. Here, computational fluid dynamics are used to reproduce the meanders and braids in rivulets flowing down an inclined channel. Fast oscillations of the meander (f = 5.6 Hz) are observed at low flow rates. At greater flow rates, an analysis of the transversal velocity in the retraction waves shows the effect of the surface tension, which causes the braiding phenomenon, and thus, the reduction in gas-liquid interface area.

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