TURBULENT FLOW TRANSITION NEAR SOLID AND FLEXIBLE BOUNDARIES.
Abstract
Transition to turbulent flow was studied in a channel in which the walls could be interchanged so that both solid and flexible walls could be investigated. The flow fluctuations were measured with a hot film anemometer. Intermittency of the fluctuations was used as a criterion of the transition condition. Turbulence spectra were measured in the transition region and in the region where continuous turbulence had been established near the walls of the channel but did not extend all the way across. Turbulence spectra fall on a uniform curve when the relative band level was plotted against Strouhal number. Band spectrum levels rise from very low Strouhal numbers and fall approximately as S to the -2.5th power for high Strouhal numbers. The intermittency is a useful factor for describing flow transition. The intermittency factor increases fairly rapidly near the wall at a distance from the channel entrance governed by the flow velocity and the wall compliance. The intermittency factor increases as the wall is approached until the sublayer is reached. Flow fluctuations are amplified near walls. Solid walls produce the largest amplification. When amplitudes increase beyond a finite limit, random fluctuation characteristics of turbulence are encountered. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1966
- Accession Number
- AD0635582
Entities
People
- Henry B. Karplus
Organizations
- IIT Research Institute