arXiv subjects

Erick M. Franklin

Publications and source records attributed to Erick M. Franklin.

3 recordsLinked to original sources

arXiv2025

Role of Friction on the Formation of Confined Granular Structures

Unstable systems of fluidized grains in a very-narrow vertical tube can auto-defluidize after some time, the settling particles forming either a glass- or crystal-like structure. We carried out experiments using different polymer spheres, of known friction and roughness, fluidized in water. A diagram was obtained for the \RefereeA{shell-settled} particles when the coefficient of friction is of the order of 0.1, and their structure is characterized through an analysis of the nearest neighbors' angles. We show that the level of velocity fluctuations is higher for the high friction material, and that, once defluidized, the decrease in the coefficient of sliding friction leads to more organized (crystal-like) structures, while those with higher friction coefficients are amorphous (glass-like structures). Our results bring new insights for understanding the formation of glass- and crystal-like structures based on the material surface properties.

cond-mat.soft↗

arXiv2025

Resultant force on grains of a real sand dune: How to measure it?

Dunes are bedforms found on sandy terrains shaped by fluid flow on Earth, Mars, and other celestial bodies. Despite their prevalence, understanding dune dynamics at the grain scale is challenging due to the vast number of grains involved. In this study, we demonstrate a novel approach to estimate the forces acting on individual dune grains using images. By combining subaqueous experiments, high-speed camera recordings, discrete numerical simulations, and a specially trained convolutional neural network, we can quantify these forces with high accuracy. This method represents a breakthrough in studying granular dynamics, offering a new way to measure forces not only on dune grains but also on smaller objects, such as rocks, boulders, rovers, and man-made structures, observed in satellite images of both Earth and Mars. This technique expands our ability to analyze and understand fluid-grain interactions in diverse environments.

physics.geo-ph↗

arXiv2018

Role of transverse displacements in the formation of subaqueous barchan dunes

Crescentic shape dunes, known as barchan dunes, are formed by the action of a fluid flow on a granular bed. These bedforms are common in many environments, existing under water or in air, and being formed from grains organized in different initial arrangements. Although they are frequently found in nature and industry, details about their development are still to be understood. In a recent paper [C. A. Alvarez and E. M. Franklin, Phys. Rev. E 96, 062906 (2017)], we proposed a timescale for the development and equilibrium of single barchans based on the growth of their horns. In the present Letter, we report measurements of the growth of horns at the grain scale. In our experiments, conical heaps were placed in a closed conduit and individual grains were tracked as each heap, under the action of a water flow, evolved to a barchan dune. We identified the trajectories of the grains that migrated to the growing horns, and found that most of them came from upstream regions on the periphery of the initial heap, with an average displacement of the order of the heap size. In addition, we show that individual grains had transverse displacements by rolling and sliding that are not negligible, with many of them going around the heap. The mechanism of horns formation revealed by our experiments contrasts with the general picture that barchan horns form from the advance of the lateral dune flanks due to the scaling of migration velocity with the inverse of dune size. Our results change the way in which the growth of subaqueous barchan dunes is explained.

cond-mat.soft↗