Friedrich F. Dunne | Searcharxiv

arXiv2019

Implementation of Morse-Witten theory for a polydisperse wet 2D foam simulation

The Morse-Witten theory (D. Morse and T. Witten, EPL 22 (1993) 549-555) provides a formulation for the inter-bubble forces and corresponding deformations in a liquid foam, accurate in the limit of high liquid fraction. Here we show how the theory may be applied in practice, including allowing for polydispersity in the bubble sizes. The resulting equilibrated 2D structures are consistent with direct calculations, within the limitations of the theory. The path to developing a 3D model is outlined for future work.

cond-mat.soft↗

arXiv2017

2D foams above the jamming transition: Deformation matters

Jammed soft matter systems are often modelled as dense packings of overlapping soft spheres, thus ignoring particle deformation. For 2D (and 3D) soft disks packings, close to the critical packing fraction $φ_c$, this results in an increase of the average contact number $Z$ with a square root in $φ-φ_c$. Using the program PLAT, we find that in the case of idealised two-dimensional foams, close to the wet limit, $Z$ increases linearly with $φ-φ_c$, where $φ$ is the gas fraction. This result is consistent with the different distributions of separations for soft disks and foams at the critical packing fraction. Thus, 2D foams close to the wet limit are not well described as random packings of soft disks, since bubbles in a foam are deformable and adjust their shape. This is not captured by overlapping circular disks.

physics.comp-ph↗