Enhancement of liquid-liquid phase transition under shear flow
Abstract
In a liquid--liquid transition (LLT), a single-component liquid transforms into another liquid with different density and viscosity. Flow therefore couples to the transition, but the effect of shear flow is not understood. Here we investigate the LLT under shear with a two-order-parameter hydrodynamic model in which the viscosity depends on the non-conserved structural order parameter. Under shear, a fluctuation of the order parameter drives a compressional flow through the viscosity, and the resulting density change enhances the order parameter fluctuation. In a linear analysis, this feedback destabilizes the metastable liquid above a critical shear rate γ̇c for wavevectors in particular directions. Because the flow rotates the wavevector, a fluctuation grows only for a finite time duration, and its amplification is determined by the dimensionless shear rate γ̇/γ̇c and the second dimensionless number Λ, the ratio of the thermodynamic relaxation rate of the order parameter to γ̇c. In hydrodynamic simulations, shear above about γ̇c induces the transition in the metastable region when Λ≳1. The transition proceeds by nucleation of domains whose morphology becomes anisotropic. The incubation time decreases and the onset of the viscosity increase is accelerated as γ̇ and Λ increase. These results imply that the shear rate is a control variable of LLT in addition to temperature and pressure, selecting whether and how a metastable liquid transforms.
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BibTeX
@misc{takae2026enhancement,
title = {{Enhancement of liquid-liquid phase transition under shear flow}},
author = {Kyohei Takae},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.25243},
eprint = {2610.25243},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.25243},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Enhancement of liquid-liquid phase transition under shear flow
AU - Kyohei Takae
PY - 2026
DA - 2026/10/18
PB - arXiv
DO - 10.48550/arxiv.2610.25243
UR - https://arxiv.org/abs/2610.25243
AB - In a liquid--liquid transition (LLT), a single-component liquid transforms into another liquid with different density and viscosity. Flow therefore couples to the transition, but the effect of shear flow is not understood. Here we investigate the LLT under shear with a two-order-parameter hydrodynamic model in which the viscosity depends on the non-conserved structural order parameter. Under shear, a fluctuation of the order parameter drives a compressional flow through the viscosity, and the resulting density change enhances the order parameter fluctuation. In a linear analysis, this feedback destabilizes the metastable liquid above a critical shear rate γ̇_c for wavevectors in particular directions. Because the flow rotates the wavevector, a fluctuation grows only for a finite time duration, and its amplification is determined by the dimensionless shear rate γ̇/γ̇_c and the second dimensionless number Λ, the ratio of the thermodynamic relaxation rate of the order parameter to γ̇_c. In hydrodynamic simulations, shear above about γ̇_c induces the transition in the metastable region when Λ≳1. The transition proceeds by nucleation of domains whose morphology becomes anisotropic. The incubation time decreases and the onset of the viscosity increase is accelerated as γ̇ and Λ increase. These results imply that the shear rate is a control variable of LLT in addition to temperature and pressure, selecting whether and how a metastable liquid transforms.
ER -