page_title: Flotation of flexible objects
section_title: History
hierarchical_section_title: Flotation of flexible objects / History
caption_attribution_description: English: Water strider (Gerris spp.)
context_page_description: Flotation of flexible objects is a phenomenon in which the bending of a flexible material allows an object to displace a greater amount of fluid than if it were completely rigid. This ability to displace more fluid translates directly into an ability to support greater loads, giving the flexible structure an advantage over a similarly rigid one. Inspiration to study the effects of elasticity are taken from nature, where plants, such as black pepper, and animals living at the water surface have evolved to take advantage of the load-bearing benefits elasticity imparts.
context_section_description: In his work "On Floating Bodies", Archimedes famously stated:
  Any object, wholly or partially immersed in a fluid, is buoyed up by a force equal to the weight of the fluid displaced by the object.
  — Archimedes of Syracuse
  While this basic idea carried enormous weight and has come to form the basis of understanding why objects float, it is best applied for objects with a characteristic length scale greater than the capillary length. What Archimedes had failed to predict was the influence of surface tension and its impact at small length scales.
  More recent works, such as that of Keller, have extended these principles by considering the role of surface tension forces on partially submerged bodies. Keller, for instance, demonstrated analytically that the weight of water displaced by a meniscus is equal to the vertical component of the surface tension force.
  Nonetheless, the role of flexibility and its impact on an object's load-bearing potential is one that did receive attention until the mid-2000s and onward. In an initial study, Vella  studied the load supported by a raft composed of thin, rigid strips. Specifically, he compared the case of floating individual strips to floating an aggregation of strips, wherein the aggregate structure causes portions of the meniscus (and hence, resulting surface tension force) to disappear. By extending his analysis to consider a similar system composed of thin strips of some finite bending stiffness, he found that this later case in fact was able support a greater load.
  A well known work in the area of surface tension aided flotation was the analysis of water strider locomotion along the surface of water.  Using the idea of flexible structures, Ji et al. re-examined this problem by considering the compliance of a water strider leg. By modeling the leg as a compliant structure that deforms at the water surface (rather than pierce it), Ji was able to ascertain what added benefit this flexibility has in supporting the insect. Other studies on the water strider have examined the ways in which flexibility can affect wetting properties of the leg.
  Another track of research has been to investigate how exactly the interaction between liquid and a compliant object leads to the resulting deformation. In one example, such analysis has been extended to explain the difficulty in submerging hairs in a fluid. These works focus on behavior near the contact line, and consider what role non-linear effects such as slippage play.
caption: The well known phenomena by which water striders support themselves through surface tension effects can be re-examined by considering the compliance and resultant deformation of the insect's leg at the water line.
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