THERMAL-CONDUCTIVITY OF A SHEARING MOLECULAR FLUID

We have investigated the thermal conductivity tenser of strongly sheared atomic and molecular liquids by computer simulation methods. According to linear nonequilibrium thermodynamics, heat and transverse momentum transport are uncoupled in the linear regime. We also expect the thermal conductivity to be independent of the zero-wavevector strain rate in the linear regime. Away from the linear regime, the situation is different. Although even a large zero-wavevector strain rate cannot induce a heat flux, the thermal conductivity can become strain-rate dependent. Furthermore, the thermal conductivity becomes a tenser because a strong velocity profile can destroy the isotropy of a fluid. These effects are only apparent at extremely high strain rates for atomic liquids, but are experimentally observable for polymeric liquids.