ABSTRACT
In the early nineteenth century, an English physician, Thomas Young, observed the liquid contact angle on a ridge surface and discovered the phenomena of capillary action on the principle of surface tension; a French scientist, Simon-Pierre Laplace, discovered the signi cance of meniscus radii with respect to capillary action. These discoveries led to the hydrostatic YoungLaplace pressure (ΔP) at a curved interface as a landmark of the eld, where the pressure difference traversing the boundary is proportional to the mean curvature, that is, the average of two principle radii of curvature at the interface (or average of the maximum κ1 and minimum κ2 curvature values of this interface). The Young-Laplace pressure can explain shape factors such as the reason for small bubbles to merge themselves into connected large ones.
