ABSTRACT
VISCOSITY The viscosity of a fluid undergoing laminar flow relates the gradient of the fluid’s velocity field to the shear stress needed to maintain the flow.
To further develop this notion, consider the situation in which homogeneous fluid completely fills a region of space lying between two [large1] parallel planar surfaces. A microscopic layer of fluid binds tightly to each of the surfaces. Suppose that one of the surfaces is forced into uniform “sideways” motion at speed v0, while remaining parallel. A constant applied force, F A , is required to keep the plate moving at constant speed.
