What is the concept of shear stress in fluid mechanics?

Shear Stress in Fluid Mechanics

Shear stress in fluid mechanics is a type of stress that acts parallel to the surface of a material, in this case, a fluid. It is caused by the motion of different layers of fluid moving at different velocities relative to each other.

Factors Affecting Shear Stress

Viscosity: Viscosity of the fluid plays a significant role in determining shear stress. Higher viscosity fluids tend to have higher shear stress compared to lower viscosity fluids.

Velocity Gradient: The rate of change of velocity with respect to distance in a fluid layer, known as velocity gradient, also affects shear stress. A higher velocity gradient results in higher shear stress.

Flow Regime: The type of flow regime, such as laminar or turbulent flow, affects shear stress. Turbulent flow generally has higher shear stress compared to laminar flow.

Boundary Conditions: The boundary conditions at the solid-fluid interface can impact shear stress. Smooth boundaries tend to have lower shear stress compared to rough boundaries.