arXiv subjects

Bruno Issenmann

Publications and source records attributed to Bruno Issenmann.

6 recordsLinked to original sources

arXiv2026

Shear and bulk viscosities of water up to 1.6 GPa and anomaly in the structural relaxation time

Deep in the Earth's crust, pressure exceeds one thousand times the atmospheric pressure. Water still flows under these conditions, but experiences dramatic changes in structure and fluidity. Using combined dynamic and inelastic light scattering techniques, we simultaneously measure the shear and bulk viscosities of water as a function of pressure. The former increases faster than the latter, so that their ratio shows a two-fold decrease from 0 to 1.6 GPa; we confirm this trend with simulations. We analyze our results in terms of the structural relaxation time $\tau$. Contrary to other liquids, pressure initially accelerates relaxation in water. Our measurements reveal that $\tau$ reaches a minimum close to 1 ps around 0.5 GPa. We interpret $\tau$ as a the equilibration time of hydrogen bonds, and propose that the minimum in $\tau$ arises from a structural anomaly which allows fastest interconversion between local structures in water, and generates a cascade of thermodynamic and dynamic anomalies.

cond-mat.soft↗

arXiv2023

Viscosity and Stokes-Einstein relation in deeply supercooled water under pressure

We report measurements of the shear viscosity $\eta$ in water up to $150\,\mathrm{MPa}$ and down to $229.5\,\mathrm{K}$. This corresponds to more than $30\,\mathrm{K}$ supercooling below the melting line. The temperature dependence is non-Arrhenius at all pressures, but its functional form at $0.1\,\mathrm{MPa}$ is qualitatively different from that at all pressures above $20\,\mathrm{MPa}$. The pressure dependence is non-monotonic, with a pressure-induced decrease of viscosity by more than 50 % at low temperature. Combining our data with literature data on the self-diffusion coefficient $D_\mathrm{s}$ of water, we check the Stokes-Einstein relation which, based on hydrodynamics, predicts constancy of $D_\mathrm{s} \eta/T$, where $T$ is the temperature. The observed temperature and pressure dependence of $D_\mathrm{s} \eta/T$ is analogous to that obtained in simulations of a realistic water model. This analogy suggests that our data are compatible with the existence of a liquid-liquid critical point at positive pressure in water.

cond-mat.soft↗

arXiv2021

Isotope effect on the anomalies of water: a corresponding states analysis

Light and heavy water show similar anomalies in thermodynamic and dynamic properties, with a consistent trend of anomalies occurring at higher temperature in heavy water. Viscosity also increases faster upon cooling in heavy water, causing a giant isotope effect, with a viscosity ratio near 2.4 at 244 K. While a simple temperature shift apparently helps in collapsing experimental data for both isotopes, it lacks a clear justification, changes value with the property considered, and requires additional ad hoc scaling factors. Here we use a corresponding states analysis based on the possible existence of a liquid-liquid critical point in supercooled water. This provides a coherent framework which leads to the collapse of thermodynamic data. The ratio between dynamic properties of the isotopes is strongly reduced. In particular, the decoupling between viscosity $\eta$ and self-diffusion $D$, measured as a function of temperature $T$ by the Stokes-Einstein ratio $D\eta/T$, is found to collapse after applying the corresponding states analysis. Our results are consistent with simulations and suggest that the various isotope effects mirror the one on the liquid-liquid transition.

physics.chem-ph↗

arXiv2021

Shear viscosity and Stokes-Einstein violation in supercooled light and heavy water

We report shear viscosity of heavy water supercooled $33\,\mathrm{K}$ below its melting point, revealing a 15-fold increase compared to room temperature. We also confirm our previous data for the viscosity of supercooled light water, and reach a better accuracy. Our measurements, based on the spontaneous Brownian motion of $350\,\mathrm{nm}$ spheres, disagree at the lowest temperature with the only other available data, based on Poiseuille flow in a narrow capillary, which may have been biased by electro-osmotic effects. The viscosity ratio between the two isotopes reaches 2.2 at the lowest temperature. A companion Letter [F. Caupin, P. Ragueneau, and B. Issenmann, arXiv:2112.09010] discusses this giant dynamic isotopic effect. Here we provide a detailed description of the experiment and its analysis. We review the literature data about dynamic properties of water (viscosity, self-diffusion coefficient, and rotational correlation time), discuss their temperature dependence and compare their decoupling in the two isotopes.

physics.chem-ph↗

arXiv2016

Wave turbulence in a two-layer fluid: coupling between free surface and interface waves

We experimentally study gravity-capillary wave turbulence on the interface between two immiscible fluids of close density with free upper surface. We locally measure the wave height at the interface between both fluids by means of a highly sensitive laser Doppler vibrometer. We show that the inertial range of the capillary wave turbulence regime is significantly extended when the upper fluid depth is increased: The crossover frequency between the gravity and capillary wave turbulence regimes is found to decrease whereas the dissipative cut-off frequency of the spectrum is found to increase. We explain these observations by the progressive decoupling between waves propagating at the interface and the ones at the free surface, using the full dispersion relation of gravity-capillary waves in a two-layer fluid of finite depths. The cut-off evolution is due to the disappearance of parasitic capillaries responsible for the main wave dissipation for a single fluid.

physics.flu-dyn↗

arXiv2012

Gravity wave turbulence revealed by horizontal vibrations of the container

We experimentally study the role of the forcing on gravity-capillary wave turbulence. Previous laboratory experiments using spatially localized forcing (vibrating blades) have shown that the frequency power-law exponent of the gravity wave spectrum depends on the forcing parameters. By horizontally vibrating the whole container, we observe a spectrum exponent that does not depend on the forcing parameters for both gravity and capillary regimes. This spatially extended forcing leads to a gravity spectrum exponent in better agreement with the theory than by using a spatially localized forcing. The role of the vessel shape has been also studied. Finally, the wave spectrum is found to scale linearly with the injected power for both regimes whatever the forcing type used.

physics.flu-dyn↗