UCD Wave Group Seminar

Time: 2.00 PM

Date: Friday November 16th 2012

Location: Merrion Seminar Room (ground floor, Block 9-10 Nexus UCD, Belfield Office Park)

I) Speaker: Claudio Viotti (UCD)

Title: Evolution of perturbations in wave-induced stratified shear layers

Abstract: Previous studies have shown that Kelvin-Helmholtz type instability is frequent within internal-wave induced shear layers, possibly leading to wave breaking and production of turbulence. Even though the established theory for parallel shear flows provides a tool for understanding the basic instability mechanism, recently it has been also recognized that the analogy between the parallel and non-parallel cases is only superficial. This study aims to refine the understanding of shear-induced instability in the specific context of internal gravity waves, and to identify the mechanisms that eventually make the onset of shear instability for such flows a significantly more subtle mechanism than its parallel counterpart.

II)Speaker: Francesco Carbone (UCD)

Title: Signal analysis and decomposition techniques

Abstract: All natural phenomena, are the result of many nonlinearly interacting processes, therefore any linear analysis has the potential risk of underestimating, or even missing, a great amount of information content. For this reason signal processing techniques have gained in steadily over the past few years. They are relevant in many areas of science and engineering and have transformed the character of instrumentation used in the laboratory. Techniques such as proper orthogonal decomposition (POD) or the empirical mode decomposition (EMD) have become necessary and powerful data analysis tools used to create low dimensional approximations of high dimensional systems (large data sets). The application of these techniques is similar to that of Fourier analysis, except that it normally requires far less modes to represent the system within a desired level. The fields of image processing, optics, oceanography, and turbulent flows are just a few of the areas where POD or EMD are implemented.

Series: Wave Group Seminar Series