The Load Supported by Small Floating Objects

Abstract

We consider the equilibrium flotation of a two-dimensional cylinder and a sphere at an interface between two fluids. We give conditions on the density and radius of these objects for them to be able to float at the interface and discuss the role played by the contact angle in determining these conditions. For cylinders with a small radius, we find that the maximum density is independent of contact angle but that, for spheres, the contact angle enters at leading order in the particle radius. Our theoretical predictions are in agreement with experimental results.

Enhanced load-carrying capacity of hairy surfaces floating on water

“…This means that a superhydrophonic cylinder can be lifted up from water much easier than a normally hydrophobic one. Our finding here is consistent with known concepts about the roles of surface hydrophobicity on the floating of a single cylinder on water [25][26][27][28]. For a given hairy surface, the total sinking or lifting energy needed to put it at a certain position is equal to the negative work done by the buoyant force.…”

Interfacial propulsion by directional adhesion

“…The dynamics of water-walking insects and spiders have received considerable recent attention [18,19,20,21], in part because it touches on the burgeoning field of water-repellency [13,14,15,8].…”

Supporting Force Test of Living Water Strides on Water Surface and Mechanical Analysis

“…The buoyancy force is vertically upward, which can be obtained by integrating the hydrostatic pressure over the water strider's legs in contact with water [7][8], and is equal to water displacement of rectangle ABCE drawn by dashed lines in Figure. legs. The surface tension is in the tangential direction of Point B on liquid-gas interface, and the expression of its vertical component is…”

“…The vertical component of surface tension was obtained by integrating the curvature pressure over the water strider's legs in contact with water [7][8], which is equal to the sum of water displacement of AME area and water displacement of BCN area in Figure3. Since the both sides of dimple caused by water strider's leg are symmetrical, the horizontal components of surface tension cancel out each other. In vertical direction, water strider's leg is subject to the pressure, buoyancy force and vertical component of surface tension; the upward force and the downward force are a pair of balanced force.…”