Filling transition for a wedge

Abstract

We study the formation and the shape of a liquid meniscus in a wedge with opening angle 2 ϕ which is exposed to a vapor phase. By applying a suitable effective interface model, at liquid-vapor coexistence and at a temperature T ϕ we find a filling transition at which the height of the meniscus becomes macroscopically large while the planar walls of the wedge far away from its center remain nonwet up to the wetting transition occurring at T w > T ϕ .Depending on the fluid and the substrate potential the filling transition can be either continuous or discontinuous. In the latter case it is accompanied by a owprefilling line extending into the vapor phase of the bulk phase diagram and describing a transition from a small to a large, but finite, meniscus height.The filling and the prefilling transitions correspond to nonanalyticities in the surface and line contributions to the free energy of the fluid, respectively.

Charged colloidal particles in a charged wedge: do they go in or out?

“…We would expect that layering transitions would then play an important role, similar to those found for neutral particles in neutral wedges [40,41]. Then one could, in principle, think about using charged colloids in charged wedges as a model system for wetting transitions such as the wedge filling transition [51][52][53].…”

Density functional study of condensation in capped capillaries

“…In our computations we fixed ρ 0 = 1 and varied the remaining substrate parameters, ε 0 , σ 0 and H 0 . In the present work we restrict our attention to combinations of ε 0 , σ 0 and H 0 , which give rise to first-order wetting in the planar wall case, as they typically exhibit a rich surface phase behavior [11,21,29]. Another criterion for the specific choices of ε 0 , σ 0 and H 0 was to illustrate different possible wetting scenarios.…”

“…We consider a number of examples which demonstrate the richness of the fluid phase behavior and are suggestive of the general features of wetting in nano-sized capped capillaries. For example, we explore in detail the connections in wetting of capped capillaries and wedgeshaped pores, since the capped capillary shown in figure 1 can be viewed as a right-angled wedge near the origin and as H → ∞ [29]. Moreover, we find that the formation of prewetting films, which occurs for sufficiently large H and forμ pw < µ c , whereμ pw corresponds to the shifted prewetting of the walls of a slit pore of width H [30], is a continuous transition in capped capillaries, as opposed to the associated slit pores in which the transition is first order [19].…”

Critical wetting in power-law wedge geometries

“…Note that by increasing the exponent γ the wall morphology can be changed smoothly from a planar substrate (γ = 0) to a linear wedge (γ = 1) and eventually to a parallel plate geometry (γ = ∞). The adsorption properties and interfacial fluctuation effects in each of these geometries, corresponding to wetting [20,21], filling [9,10,11] and capillary condensation [21], respectively, are very different to each other and have received considerable theoretical and experimental interest. The central question we ask here is, how do the wetting properties depend on the wall exponent γ?…”

“…Hereafter, we restrict our attention to the regime γ ≤ 1 and focus on the fate of the planar wetting transition as γ is increased from 0 to 1. The critical behaviour occurring at the limit γ = 1, corresponding to the filling of a linear wedge, is known in some detail [9,10,11]. Writing the wall-function z(x, y) = tan α |x|, with α the tilt angle, observe that the ratio r = sec α > 1.…”