Linear shear flow past a hemispherical droplet adhering to a solid surface

Sugiyama, Kazuyasu; Sbragaglia, Mauro

doi:10.1007/s10665-007-9185-z

Cited by 31 publications

(27 citation statements)

References 27 publications

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“…As the drops start to move, both deform, with the top tilting downstream (figure 11, t = 155). This is similar to the shape of a single pinned bubble predicted by asymptotic theories (Feng & Basaran 1994;Sugiyama & Sbragaglia 2008). Such bubble deformation creates a relatively narrow gap between the drops, where the velocity of the surrounding fluid is suppressed by viscosity.…”

Section: Coalescence Driven By External Flowsupporting

confidence: 80%

Motion and coalescence of sessile drops driven by substrate wetting gradient and external flow

Ahmadlouydarab

Feng

2014

J. Fluid Mech.

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We report two-dimensional simulations of drop dynamics on a substrate subject to a wetting gradient and an external pressure gradient along the substrate. A phase-field formulation is used to represent the drop interface, and the moving contact line is modelled by Cahn-Hilliard diffusion. The Navier-Stokes-Cahn-Hilliard equations are solved by finite elements on an adaptively refined unstructured grid. For a single drop and a pair of drops, we consider three scenarios of drop motion driven by the wetting gradient only, by the external flow only, and by a combination of the two. Both the capillary force and the hydrodynamic drag depend strongly on the shape of the drop. Since the drop adapts its shape to the local wetting angles and to the external flow on a finite time scale, hysteresis is a prominent feature of the drop dynamics under opposing forces. For each wetting gradient, there is a narrow range of the magnitude of the external flow within which a single drop can achieve a stationary state. The equilibrium drop shape and position depend on its initial shape and the history of forcing. For a pair of drops, the wetting gradient or external flow alone tends to produce catch-up and coalescence. The flow-driven coalescence arises from a viscous shielding effect that relies on the asymmetric shape of the trailing drop once it is deformed by flow. This mechanism operates at zero Reynolds number, but is much enhanced by inertia. With the two forces opposing each other, the external flow favours separation while the wetting gradient favours coalescence. The outcome depends on their competition.

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Section: Coalescence Driven By External Flowsupporting

confidence: 80%

Motion and coalescence of sessile drops driven by substrate wetting gradient and external flow

Ahmadlouydarab

Feng

2014

J. Fluid Mech.

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“…Here k x1 is a wall correction factor accounting for the proximity of the wall, R is the radius of the drop, l is the air viscosity and V some effective velocity at the top of the droplet. For a hemispherical solid particle [34], or a hemispherical viscous droplet [35], an equivalent expression has been derived as F = k x2 (6pRlV), where k x2 will be a different correction factor. Consequently the drag force exerted on the droplet, F D , will be given by…”

Section: Analytical Modelmentioning

confidence: 99%

Displacement of liquid droplets on a surface by a shearing air flow

Fan

Wilson

Kapur

2011

Journal of Colloid and Interface Science

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“…The plastron in this idealized model is of uniform thickness; as such, we consider the limit of a solid sphere with a perfect superhydrophobic surface. In flow past a gas bubble or droplet attached to a wall, flow can result in deformations of the bubble or droplet surface 24 and contribute to drag. However, because the air layer within a plastron is supported by a rigid hydrophobic surface structure it is a reasonable assumption that the layer is of uniform and constant thickness independent of the precise details of the external flow.…”

Section: Introductionmentioning

confidence: 99%