Spring Semester 2009
How can materials and surface geometry be combined to demonstrate the effects of surface tension for the purpose of enhancing certain preformative qualities of architecture? There exists a hierarchy within the behavior of water when in contact with a surface. Many droplets join to become a bead. Many beans join to become a blob. When many blobs come together, the weight, due to gravity, exceed the adhesive forces and cause a stream.
What is surface tension?
The micro effect:
Molecules in a liquid state experience strong intermolecular attractive forces. When the forces are between like molecules, they are referred to as cohesive forces. When the attractive forces are between unlike molecules, they are said to be adhesive forces. Those driving forces strive to diminish the surface area, and in this respect a liquid surface resembles a stretched elastic membrane. Surface Tension is responsible for the shape of liquid droplets. The shperical shape minimizes the necessary “wall tension” of the surface layer.
The macro effect:
When a narrow enough passageway is given, a liquid will experience capillary action. The adhesive force draws the liquid up, while the cohesive force keeps the liquid from falling back down. In liquids, surface tension occurs at the interface between unlike molecules; this can be liquid-liquid, liquid-gas, or liquid-solid. Some of the macro effects of surface tension on a liquid are: elasticity, beading, light modulation, capillary action, absorption, bubble walls, self organization, and cellular density.
The problem is that, at the human scale, the intermolecular forces of surface tension do not apply. We are posed with the problem of overcoming larger forces of nature like gravity, wind, and rain. Even forces that we humans impose upon ourselves must also be considered. These may include forces like movement, visual hierarchy, or perhaps the notion of safety. In applying the idea of surface tension to architecture, it is important to make the claim that is is not the intent to mimic the forces of surface tension, but to activate them.
The hypothesis for the study of surface tension is that droplets, beads, and blobs will be controlled through the precise configuration of geometric cross sections in a surface, to demonstrate how water can be retained and used to shade or permit light, and how streams can be used to define the characteristics of a structure.