1. MAE 5130: VISCOUS FLOWS Introduction to Turbulent Flows
November 23, 2010
Mechanical and Aerospace Engineering Department
Florida Institute of Technology
D. R. Kirk

2. SAMPLE STEADY TURBULENT DATA
Sampling time = 10 seconds, Sampling rate = 100 Hz
Function f: ± 10 % fluctuation around a mean of 5
Function g: ± 2 % fluctuation around a mean of 10

3. STATISTICAL ANALYSIS

4. AVERAGING POSTULATES

5. EXPERIMENTAL DATA AND SCALED TURBULENT BOUNDARY LAYER VELOCITY PROFILES
Wall layer: Viscous shear dominates
(tlam >>> tturb)
Outer layer: Turbulent shear dominates
(tlam <<< tturb)
Overlap layer: Both types of shear important
(tlam ~tturb)

6. TURBULENT BOUNDARY LAYER SCALING

7. EXPERIMENTAL VERIFICATION OF INNER-, OUTER-, AND OVERLAP-LAYER LAWS RELATING VELOCITY PROFILES IN TURBULENT WALL FLOW

8. COMMENTS ON ROUGH WALLS
IF e+ < 5
Hydraulically smooth walls
No effect of roughness on friction
IF 5 < e+ < 70
Transitional roughness
Moderate Reynolds-number effect
IF e+ > 70
Fully rough flow
Sublayer is totally broken up and friction is independent of Reynolds number

9. THE MOODY CHART