Molecular interpretation of the non-Newtonian viscoelastic behavior of liquid water at high frequencies

Abstract

Using classical and $a\phantom{\rule{0}{0ex}}b$ $i\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}o$ molecular dynamics simulations, we calculate the frequency-dependent shear viscosity of pure liquid water and water--glycerol mixtures. In agreement with recent experiments, we find deviations from Newtonian-fluid behavior in the THz regime, and introduce a continuum viscoelastic model (CVM) to describe the observed viscosity spectrum of pure water. We relate features of the CVM to the microscopic dynamics of water molecule clusters. Our model bridges hydrodynamic and molecular approaches to water dynamics, quantifying the viscoelastic response on short timescales where a Newtonian-fluid model breaks down.

Topics & Concepts