02896 IUPAC Gold Book - hydrodynamically equivalent sphere 10.1351/goldbook.H02896 H02896 current 1 A hypothetical sphere, impenetrable to the surrounding medium, displaying in a hydrodynamic field the same frictional effect as an actual polymer molecule. The size of a hydrodynamically equivalent sphere may be different for different types of motion of the macromolecule, e.g. for diffusion and for viscous flow. diffusion https://goldbook.iupac.org//terms/view/D01716 polymer molecule https://goldbook.iupac.org//terms/view/M03667 Purple Book, 1st ed., p. 60 (http://old.iupac.org/publications/books/author/metanomski.html) https://goldbook.iupac.org/terms/view/H02896/html https://goldbook.iupac.org/terms/view/H02896/json https://goldbook.iupac.org/terms/view/H02896/plain Citation: 'hydrodynamically equivalent sphere' 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.H02896 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. If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org . 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. 2026-07-27T23:36:29+00:00