Wall Shear Stress in Hypersonic Viscous Flow

– Hypersonic and High-Temperature Gas Dynamics, John D. Anderson, Jr.

In boundary layer theory, this equation is crucial for determining the shear stress exerted on a surface submerged in a fluid flow. It plays a pivotal role in calculating skin-friction drag, a significant component of the total aerodynamic drag that a body encounters while moving through a fluid. This equation is particularly relevant in contexts such as hypersonic flight, where the wall shear stress significantly impacts the aerodynamic performance of an aircraft.

• τ_{w: Wall shear stress, which represents the force per unit area exerted by the fluid on the surface due to viscosity.}
• μ_w: Dynamic viscosity of the fluid at the wall. It is a property of the fluid that measures its resistance to deformation (flow).
• (∂y/∂u​)_w: Velocity gradient at the wall, which is the rate of change of the velocity u in the direction normal (perpendicular) to the wall (denoted by y).​