Onset of menisci

Abstract

When a vertical solid is brought in contact with the surface of a wetting liquid, a meniscus starts rising up the solid, until it reaches its steady state. We study this dynamical phenomenon experimentally with liquids of low and high viscosity, and taking as solids either large rods or small fibres. In the inviscid limit, we show that the rising time scales as √(ρr30/σ), where ρ and σ are the density and surface tension of the wetting liquid and r0 the radius of the fibre. This characteristic time holds for small fibres, with radii smaller than the capillary length a. For large rods or planar solids, r0 is replaced by a in the expression for the rising time. In the viscous limit, the rising time scales as ηr0/σ where η is the dynamical viscosity. Again, r0 is replaced by the capillary length a for large rods.