Shear stress in fluids
Any real fluids (liquids and gases included) moving along solid boundary will incur a shear stress on that boundary. The shear stress is imparted onto the boundary as a result of this loss of velocity. The shear stress, for a Newtonian fluid, at a surface element parallel to a flat plate, at the point y, is given by:
where
is the dynamic viscosity of
the fluid;
is the velocity of the fluid
along the boundary;
is the height above the boundary.
Specifically, the wall shear stress is defined as:
In case of wind, the shear stress at the boundary is called wind stress
Picture
Reference
(Stress shear)
