This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
Unformatted text preview: The Turbulent Flat Plate Boundary Layer (Section 10-6, Ç engel and Cimbala) The turbulent flat plate boundary layer velocity profile : The time-averaged turbulent flat plate (zero pressure gradient) boundary layer velocity profile is much fuller than the laminar flat plate boundary layer profile, and therefore has a larger slope ∂ u / ∂ y at the wall, leading to greater skin friction drag along the wall. Re x , cr = 5 × 10 5 Note: The vertical scale is exaggerated for clarity. We define the engineering critical Reynolds number: • Re x < Re x , cr BL most likely laminar • Re x > Re x , cr BL most likely turbulent τ w = µ∂ u / ∂ y at y = 0 There are three common empirical relationships for the turbulent flat plate boundary layer velocity profile: • The one-seventh-power law : • The log law : • Spalding’s law of the wall : Quantities of interest for the turbulent flat plate boundary layer : Just as we did for the laminar (Blasius) flat plate boundary layer, we can use these expressions...
View Full Document
- Fall '05
- Aerodynamics, Rex, plate boundary layer, turbulent flat plate