This chapter provides an overview of measurement of viscosity. Issac Newton postulated that "the resistance which arises from the lack of slipperiness of the parts of the liquid, other things being equal, is proportional to the velocity with which parts of the liquid are separated from one another." This "lack of slipperiness" is called viscosity. For simple liquids like water, the viscosity can depend on the pressure and temperature, but not on the velocity gradient (i.e., shear rate). If such materials satisfy certain further formal requirements (e.g., that they are inelastic), they are referred to as Newtonian viscous fluids. However, it is clearly impracticable to construct viscometers with the infinite planar geometry associated with Newton's postulate, especially in the case of mobile liquid systems, and this has led to the search for convenient geometries and flows that have the same basic steady simple shear flow structure. This problem has now been resolved and a number of the so-called "viscometric flows" are used as the basis for viscometer design. Further, the chapter also discusses shop-floor viscometers. © 2003 Elsevier Inc. All rights reserved.
Walters, K., & Jones, W. M. (2003). Measurement of viscosity. In Instrumentation Reference Book: Third Edition (pp. 45–52). Elsevier Inc. https://doi.org/10.1016/B978-075067123-1/50006-5