Aerodynamics - A Time Dependent Flow Model for the Inner Region of a Turbulent Boundary Layer.
Abstract
Response of the flow variables to external driving forces is non-linear for shear flows. For the turbulent boundary layer case, surface shear stress fluctuations of magnitude as great as the mean value are observed. For flow near the surface Prandtl's turbulent boundary layer approach of employing averaged Reynolds equation and a turbulence closure model is insufficient to account for surface shear fluctuations. A model which incorporates a discrete time dependent solution for the inner region of the turbulent boundary layer is proposed. The model requires stochastic averaging of the time dependent solution to account for the random aspect of the flow. The physical model for the flow near the surface is based on the bursting cycle observed in the inner region of a turbulent boundary layer. In order to confirm the time dependent model assumptions, measurements of the probability distribution and cross-correlation of the longitudinal turbulent velocity and the surface shear stress were evaluated. Results show that the mean value of surface shear and the large magnitude fluctuations of surface shear stress were reduced significantly. The variation in surface shear was found to be extremely sensitive to slight angle of attacks of the plates.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1981
- Accession Number
- ADA103353
Entities
People
- Ho-chen Chien
- V. A. Sandborn
Organizations
- Colorado State University