View source for Saffman-Taylor instability

'''Saffman-Taylor instability''' is an interfacial instability that occurs when a less viscous fluid displaces a more viscous fluid in a porous medium or a narrow gap, producing finger-like patterns that grow unstably at the interface. First analyzed by Philip Saffman and Geoffrey Taylor in 1958, the instability is governed by '''[[Darcy\'s law|Darcy\'s law]]''' and Laplacian growth dynamics, and it produces fractal-like structures in certain parameter regimes.

The instability is not merely a curiosity of [[Fluid dynamics|fluid dynamics]]. It is a paradigmatic example of pattern formation in systems where the dynamics are controlled by a harmonic field — the same mathematical structure appears in dendritic crystal growth, electrodeposition, and the growth of bacterial colonies. The fingers are not arbitrary: their width is selected by a competition between surface tension, which stabilizes short wavelengths, and the driving pressure, which destabilizes long wavelengths.

[[Category:Physics]] [[Category:Systems]]