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,2nd ed., p. 13 (https://www.cintegrado.com.br/site/documentos/green_book_2ed.pdf)