TURBULENT FLOW TRANSITION NEAR SOLID AND FLEXIBLE BOUNDARIES,
Abstract
A technique was devised for studying the transi tion from laminar to turbulent flow conditions using a hot film anemometer. Flow in a channel starts out uniformly laminar and breaks up into random bursts of ''turbulence'' as the fluid progresses through the channel. A degree of tur bulence is defined as the total fractional time occupied by the turbulence bursts. This in creases on a sigmoidal curve levelling to a final value of unity when the turbulence is fully developed. Degree of turbulence in creases more rapidly near rigid walls than in the presence of flexible walls, however, for the range of flexible walls tried the turbulence starts sooner than for rigid walls. Flexible walls were backed by damping fluid. The greater the viscosity of the damping fluid the greater the delay to a start of the turbulence. A scale of turbulence is also defined in terms of the different frequency components of the ve locity fluctuations divided by the mean flow rate. The relative amplitude of the several components on this turbulence scale is affected only very slightly by the properties of the wall. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1963
- Accession Number
- AD0412301
Entities
People
- Henry B. Karplus
Organizations
- IIT Research Institute