{"term":{"id":"06189","title":"surface shear viscosity","longtitle":"IUPAC Gold Book - surface shear viscosity","doi":"10.1351\/goldbook.S06189","code":"S06189","status":"current","also defines":"<em>also defines<\/em>: area viscosity","mentioned":"<em>mentioned<\/em>: surface dilatational viscosity","definitions":[{"id":1,"text":"For steady state deformations a surface shear viscosity \\(\\eta ^{\\rm{s}}\\), and an area viscosity or surface dilatational viscosity \\(\\zeta ^{\\rm{s}}\\) can be defined. In a Cartesian system with the x-axis normal to the surface, they are defined by the equations: \\[\\eta ^{\\rm{s}} = \\frac{\\sigma _{xy}}{\\frac{\\partial \\nu_{y}}{\\partial \\nu_{x}}}\\] \\[\\zeta ^{\\rm{s}}=\\frac{\\Delta \\gamma }{\\frac{\\mathrm{d}(\\ln A)}{\\mathrm{d}t}}\\] where \\(\\sigma _{xy}\\) is the shear component of the surface stress tensor, \\(\\nu_{x}\\) and \\(\\nu_{y}\\) are the \\(x\\) and \\(y\\) components of the surface velocity vector, respectively, \\(A\\) is the surface area, \\(t\\) is the time, and \\(\\Delta \\gamma \\) is the difference between the (steady state) dynamic surface tension and the equilibrium surface tension.","links":[{"term":"dynamic surface tension","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/D01875"},{"term":"shear viscosity","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/S05642"},{"term":"surface stress","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/S06191"}],"sources":["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 (https:\/\/doi.org\/10.1351\/pac197951051213)"]}],"altoutputs":{"html":"https:\/\/goldbook.iupac.org\/terms\/view\/S06189\/html","xml":"https:\/\/goldbook.iupac.org\/terms\/view\/S06189\/xml","plain":"https:\/\/goldbook.iupac.org\/terms\/view\/S06189\/plain"},"citation":"Citation: 'surface shear viscosity' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351\/goldbook.S06189","license":"The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/) for individual terms.","collection":"If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org .","disclaimer":"The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using.","accessed":"2026-06-29T01:32:03+00:00"}}