FLOW Paper published in Nature Communications (Dec. 2017)

The paper ‘ Laboratory layered latte’  by Xue, Khodaparast, Zhu, Nunes, Kim and Stone has been published in Nature Communications. The authors experimentally investigate the critical conditions for creation of distinct layered patterns in fluids with thermal and density gradients. The work is part of our colleague Dr. Lailai Zhu’s postdoctoral studies while visiting Princeton University.

Abstract:

Inducing thermal gradients in fluid systems with initial, well-defined density gradients results in the formation of distinct layered patterns, such as those observed in the ocean due to double-diffusive convection. In contrast, layered composite fluids are sometimes observed in confined systems of rather chaotic initial states, for example, lattes formed by pouring espresso into a glass of warm milk. Here, we report controlled experiments injecting a fluid into a miscible phase and show that, above a critical injection velocity, layering emerges over a time scale of minutes. We identify critical conditions to produce the layering, and relate the results quantitatively to double-diffusive convection. Based on this understanding, we show how to employ this single-step process to produce layered structures in soft materials, where the local elastic properties vary step-wise along the length of the material.

Nature Communications 8, Article number: 1960 (2017) doi:10.1038/s41467-017-01852-2