METHOD AND APPARATUS FOR VISUALIZING SHEARING STRESS DISTRIBUTION USING DISCRETE WAVELET CONVERSION

摘要

PROBLEM TO BE SOLVED: To quantitatively visualize in detail a liquid structure in a boundary layer on a wall surface by decomposing digital data of a fluid shearing stress of the surface into a time space frequency distribution of multiple resolution by means of discrete wavelet conversion and its inversion, and obtaining a shearing stress distribution. SOLUTION: A discrete wavelet conversion is executed at digital data of a fluid shearing stress in a boundary layer on a wall surface to obtain a discrete wavelet spectrum. The spectrum is subjected to a discrete wavelet inversion at each frequency to obtain a shearing stress distribution decomposed at a space time frequency level of the resolution. Then, the low (high) level portion exhibits a low (high) frequency component, and a large (small) vortex structure can be visualized at the low (high) level, a more detailed fluid structure can be visualized by the shearing stress distribution at each frequency level, In this case, if the digital data is two-dimensional (three-dimensional), a space curve is one-dimensional (two-dimensional), and a time base is one-dimensional.