Interfacial tension in miscible two-fluid systems with linear viscoelastic rheology.

I present observations of interfacial tension between miscible pairs of silicate liquid and propose a theoretical model that quantitatively accounts for them. Viscoelastic rheology of the liquids permits the establishment of gradient stress completely analogous to thermal stress in Maxwell solids; this is expected whenever the time scale of diffusion is shorter than the Maxwell relaxation time. The existence of gradient stress may profoundly affect interface processes during mixing of miscible fluids.