THERMAL-CONDUCTIVITY OF A SHEARING MOLECULAR FLUID

We have investigated the thermal conductivity tenser of strongly shear ed atomic and molecular liquids by computer simulation methods. Accord ing to linear nonequilibrium thermodynamics, heat and transverse momen tum transport are uncoupled in the linear regime. We also expect the t hermal conductivity to be independent of the zero-wavevector strain ra te in the linear regime. Away from the linear regime, the situation is different. Although even a large zero-wavevector strain rate cannot i nduce a heat flux, the thermal conductivity can become strain-rate dep endent. 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 li quids, but are experimentally observable for polymeric liquids.