Analysis of realistic rough surface for its globally dominant parameters using continuous wavelets.pdf

Appl. Math. Mech. -Engl. Ed., 35(6), 741–748 (2014) Applied Mathematics DOI 10.1007/s10483-014-1826-6 and Mechanics c Shanghai University and Springer-Verlag Berlin Heidelberg 2014 (English Edition) Analysis of realistic rough surface for its globally dominant parameters using continuous wavelets∗ Yan-hua WU1, Hui-ying REN2 (1. School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore; 2. Hydrology Technical Group, Pacific Northwest National Laboratory, P. O. Box 999, Richland, WA 99352, U. S. A.) Abstract Continuous Morlet and Mexican hat wavelets are used to analyze a highly irregular rough surface replicated from real turbine blades which are roughened by deposi- tion of foreign materials. The globally dominant aspect ratio, length scale, and orientation of the roughness elements are determined. These parameters extracted from this highly irregular rough surface are important for the future studies of their effects on turbulent flows over this kind of rough surfaces encountered in Washington aerospace and power generating industries. Key words continuous wavelet, Morlet wavelet, Mexican wavelet, roughness Chinese Library Classification O242.29, TU311.3 2010 Mathematics Subject Classification 42C40 1 Introduction Engineering wall-bounded turbulent flows are significantly affected by the surface roughness conditions. Examples of these flows of practical interest include both external and internal flows such as those over turb