This report, titled "Characteristics of Turbulence in a Boundary Layer with Zero Pressure Gradient," by P. S. Klebanoff, presents experimental findings on turbulent boundary layers with zero pressure gradient. The study was conducted at the National Bureau of Standards using a 41/2-foot wind tunnel and an artificially thickened boundary layer to enhance the measurement of turbulent properties. Key findings include: 1. **Intermittency**: The turbulence near the wall is intermittent, meaning it alternates between turbulent and nonturbulent periods. This intermittency is more pronounced in the outer region of the boundary layer, where the flow is less affected by the wall. 2. **Energy Balance**: The energy balance equation for turbulence is analyzed, showing that dissipation is greater than production in a thin region near the wall. This suggests a diffusion of energy towards the wall, which contradicts the intuition that energy should move away from the wall due to pressure forces. 3. **Spectral Distributions**: Spectra of turbulent energy and shear stress are measured, providing insights into the spatial distribution of turbulent motions. The spectra reveal that the large-scale motions responsible for shear stress are more influenced by viscosity than the small-scale motions. 4. **Probability Distribution and Skewness**: The probability density and skewness of \( u \)-fluctuations are studied, showing that the probability distribution is strongly negatively skewed in the turbulent regions. The skewness and flattening factors are calculated and compared with theoretical values. 5. **Derivatives and Correlation Coefficients**: The derivatives of velocity components and correlation coefficients are measured to assess the validity of the local isotropy hypothesis. The results indicate that the space-time transformation used to simplify the dissipation calculation is valid for small-scale motions but breaks down for larger-scale motions. The report concludes that the turbulent energy dissipation is significantly influenced by the wall, and the intermittency plays a crucial role in the energy balance and spectral distribution of turbulent motions.This report, titled "Characteristics of Turbulence in a Boundary Layer with Zero Pressure Gradient," by P. S. Klebanoff, presents experimental findings on turbulent boundary layers with zero pressure gradient. The study was conducted at the National Bureau of Standards using a 41/2-foot wind tunnel and an artificially thickened boundary layer to enhance the measurement of turbulent properties. Key findings include: 1. **Intermittency**: The turbulence near the wall is intermittent, meaning it alternates between turbulent and nonturbulent periods. This intermittency is more pronounced in the outer region of the boundary layer, where the flow is less affected by the wall. 2. **Energy Balance**: The energy balance equation for turbulence is analyzed, showing that dissipation is greater than production in a thin region near the wall. This suggests a diffusion of energy towards the wall, which contradicts the intuition that energy should move away from the wall due to pressure forces. 3. **Spectral Distributions**: Spectra of turbulent energy and shear stress are measured, providing insights into the spatial distribution of turbulent motions. The spectra reveal that the large-scale motions responsible for shear stress are more influenced by viscosity than the small-scale motions. 4. **Probability Distribution and Skewness**: The probability density and skewness of \( u \)-fluctuations are studied, showing that the probability distribution is strongly negatively skewed in the turbulent regions. The skewness and flattening factors are calculated and compared with theoretical values. 5. **Derivatives and Correlation Coefficients**: The derivatives of velocity components and correlation coefficients are measured to assess the validity of the local isotropy hypothesis. The results indicate that the space-time transformation used to simplify the dissipation calculation is valid for small-scale motions but breaks down for larger-scale motions. The report concludes that the turbulent energy dissipation is significantly influenced by the wall, and the intermittency plays a crucial role in the energy balance and spectral distribution of turbulent motions.