Mapping two-dimensional polar active fluids to two-dimensional soap and one-dimensional sandblasting

TYC scientist Chiu Fan Lee shows mathematically that the dynamics that govern swarms and bird flocks may also govern the properties of things like magnets.

Now, Dr Chiu Fan Lee from Imperial College London and his collaborators in China and the USA have formulated an equation for understanding the principles behind motility in a generic active fluid model. They compared the generic active fluid model to a well-known physical model that is governed by the Kardar-Parisi-Zhang equation.

The paper connects four seemingly distinct physical models (clockwise from top): polar active fluids, equilibrium smectics (soap),  KPZ surface growth/erosion (sandblasting), and a modified version of the XY model (magnets). Picture credits (clockwise from top): 1) Photographed by Tommy Hansen (public domain). 2) Taken from Sparavigna, A. (2016). From an Isotropic Liquid to a Nematic or a Smectic Mesophase. PHILICA.COM Article number 554. (CC BY 2.5). 3) Taken from Photographed by Christine Schultz (public domain).

The article, published in Nature Communications 7 can be found at


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