A Low-Dimensional Structural Model of a Turbulent Boundary Layer Separating Intermittently in Space
Abstract
The phenomenon of intermittent separation occurring in space on a smooth, flat plate in an incompressible turbulent boundary layer, subjected to an adverse pressure gradient barely strong enough to cause separation, is described. The effect of adverse pressure gradient on a hairpin vortex is analyzed, and the process of liftup of the near-wall vorticity to be expected during separation is discussed. These effects are then compared with the results of an experiment that explores the organized nature of the process of intermittency occurring in incipient separation. Subsequently, a low-dimensional structural model of the phenomenon of intermittency occurring in incipient separation, based on a limited number of large structures, is developed, and a comparison with the measurements of separation intermittency is made. The potential usefulness of the model to an artificial neural network for predicting the time-dependent separation process is discussed. The most important result of the proposed structural model is that there is a sequence of large structures involved in the separation process and that this sequence has a regular attractor. It is proposed that the features of the separation process are related to chaos theory.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1994
- Accession Number
- ADA637043
Entities
People
- P. R. Bandyopadhyay
Organizations
- Naval Undersea Warfare Center