Accession Number : ADA293805

Title :   Application of Wavelet-Filtering Techniques to Intermittent Turbulent and Wall Pressure Events. Part 2. Detection of Cluster Patterns.

Descriptive Note : Progress rept. Nov 94-Nov 95,

Corporate Author : CATHOLIC UNIV OF AMERICA WASHINGTON DC DEPT OF MECHANICAL ENGINEERING

Personal Author(s) : Casarella, Mario J. ; Penafiel, Pablo B. ; Kammeyer, Mark E.

PDF Url : ADA293805

Report Date : 26 APR 1995

Pagination or Media Count : 62

Abstract : Large amplitude wall-pressure events, observed beneath a turbulent boundary layer, appear to be signatures of intermittent organized motions within the turbulent flow. Experimental studies were made investigating this relationship. Part 1 presented the first phase of this investigation and reported on the results of utilizing time-frequency localization techniques (wavelet transforms) for the detection of these events. The application of wavelet filtering for the analyses of turbulent data was introduced. This report presents the results of the second phase of the investigation. A wavelet filter was selected based on maintaining the integrity of intermittent near wall burst events. The correlations between individual turbulent flow and wall-pressure events were confirmed using both the original time records and the generated VITA function time records. A Localized Windowed Peak Detection algorithm was developed that detects the groupings of these events. The algorithm detects the temporal locations and durations of the clusters. Correlation and conditional sampling methods were then used to postulate the sequential burst events contained within the individual clusters. Conditional sampling showed a bi-directional relationship between positive wall-pressure events and burst ejections in the near-wall region. (AN)

Descriptors :   *TURBULENT FLOW, *TURBULENT BOUNDARY LAYER, *PRESSURE DISTRIBUTION, VELOCITY, PRESSURE GRADIENTS, DATA BASES, MATHEMATICAL MODELS, ALGORITHMS, SIGNAL PROCESSING, PEAK VALUES, EXPERIMENTAL DATA, TIME DEPENDENCE, COMPUTATIONAL FLUID DYNAMICS, CORRELATION, FLOW FIELDS, CLUSTERING, SAMPLING, NONEQUILIBRIUM FLOW, DATA COMPRESSION, FLOW NOISE, BACKGROUND NOISE, HOT WIRE ANEMOMETERS, STEADY FLOW.

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE