The critical Reynolds number (Rexcr) is a dimensionless parameter used in fluid dynamics to characterize the transition from laminar to turbulent flow over an object, such as an airfoil or a pipe. It represents a critical threshold at which the flow behavior changes from being relatively smooth and orderly (laminar) to becoming chaotic and turbulent. The critical Reynolds number is influenced by the object’s shape, surface roughness, and other aerodynamic or hydrodynamic conditions. It varies for different flow situations and geometries.
- Rexcr: Critical Reynolds number
- ρ∞: Density of the freestream flow
- V∞: Freestream velocity
- xcr: Critical location along the chord
- μ∞: Dynamic viscosity of the freestream flow