dynamic viscosity, \(\eta\)
https://doi.org/10.1351/goldbook.D01877
For a laminar flow of a fluid the ratio of the shear stress to the velocity gradient perpendicular to the plane of shear.
See also:
viscosity
Source:
Green Book, 2
nd
ed., p. 13 (https://goldbook.iupac.org/files/pdf/green_book_2ed.pdf)