국내 최대 기계 및 로봇 연구정보

기술보고서

기술보고서 게시판 내용
타이틀	Demonstration of Wavelet Techniques in the Spectral Analysis of Bypass Transition Data
저자	Jacques Lewalle, David E. Ashpis, and Ki-Hyeon Sohn
Keyword	Wavelets; Multiresolution; Bypass transition; Transition; Boundary layers; Turbulence; Conditional-statistics; Mexican hat wavelet; Intermittency
URL	http://gltrs.grc.nasa.gov/reports/1997/TP-3555.pdf
보고서번호	NASA TP-3555
발행년도	1997
출처	NASA Glenn Research Center
ABSTRACT	A number of wavelet-based techniques for the analysis of experimental data are developed and illustrated. A multiscale analysis based on the Mexican hat wavelet is demonstrated as a tool for acquiring physical and quantitative information not obtainable by standard signal analysis methods. Experimental data for the analysis came from simultaneous hot-wire velocity traces in a bypass transition of the boundary layer on a heated flat plate. A pair of traces (two components of velocity) at one location was excerpted. A number of ensemble and conditional statistics related to dominant time scales for energy and momentum transport were calculated. The analysis revealed a lack of energy-dominant time scales inside turbulent spots but identified transport-dominant scales inside spots that account for the largest part of the Reynolds stress. Momentum transport was much more intermittent than were energetic fluctuations. This work is the first step in a continuing study of the spatial evolution of these scale-related statistics, the goal being to apply the multiscale analysis results to improve the modeling of transitional and turbulent industrial flows.