Shear stress (often denoted by τ, Greek: tau)
9/22/2025
Shear stress (often denoted by τ, Greek: tau) is the component of stress coplanar with a material cross section.
General shear stress
The formula to calculate average shear stress τ or force per unit area is:[1]τ=FA,
The area involved corresponds to the material face parallel to the applied force vector, i.e., with surface normal vector perpendicular to the force.
Other forms
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Wall shear stress
Wall shear stress expresses the retarding force (per unit area) from a wall in the layers of a fluid flowing next to the wall. It is defined as:τw:=μ∂u∂y|y=0,
It is used, for example, in the description of arterial blood flow, where there is evidence that it affects the atherogenic process.[2]
