surface shear viscosity

Also contains definitions of: area viscosity, surface dilatational viscosity
https://doi.org/10.1351/goldbook.S06189
For steady state deformations a surface
shear viscosity
ηs, and an area viscosity or surface dilatational viscosity ζs can be defined. In a Cartesian system with the x-axis normal to the surface, they are defined by the equations: ηs=σxyνyνx ζs=Δγd(lnA)dt where σxy is the shear component of the
surface stress
tensor, νx and νy are the x and y components of the surface velocity vector, respectively, A is the surface area, t is the time, and Δγ is the difference between the (steady state)
dynamic surface tension
and the equilibrium surface tension.
Source:
PAC, 1979, 51, 1213. (Terminology and Symbols in Colloid and Surface Chemistry Part 1.13. Definitions, Terminology and Symbols for Rheological Properties) on page 1218 [Terms] [Paper]