ABSTRACT
Any review on the shape of a liquid droplet on top of a solid surface has to start with the pioneering work by P.S.Laplace and Sir Thomas Young almost two centuries ago [1, 2]. Young and Laplace set out to describe the phenomenon of “capillary action” in which the liquid inside a small capillary tube may rise several centimeters above the liquid outside the tube [3]. To understand this effect, two fundamental equations were derived by Young and Laplace. The first equation, known as the Laplace or Young-Laplace equation [1], relates the curvature at a certain point of the liquid surface to the pressure difference between both sides of the surface, and we consider it next in more detail. The second equation is Young’s equation [2], which relates the contact angle to the surface tensions involved.
