Jacques Lewalle

Degree(s):

  • Ph.D., Cornell University

Research Interests:

  • Wavelet analysis (time-frequency), multiscale phenomena
  • Signal processing: aeroacoustics, flow physics in varying configurations
  • Mathematical physics of turbulent flows
  • Sound refraction of in turbulent flows

Current Research:

Extracting information from experimental (acoustic signals, PIV fields) and numerical (LES) data is like squeezing juice from various fruits. My methods combine continuous wavelet analysis of time series (time-frequency methods) with conventional statistical and signal processing tools. The same ideas are also applied to the governing equations, yielding insights into multiscale dynamics in Navier-Stokes turbulence and related topics. I am not aware of anyone with more archival publications in the area of continuous wavelets.

These tools are currently applied to the problem of jet noise, achieving some success in the remote identification of individual near-field sources. This is combined with the analysis of near-field velocity from time-resolved PIV and computer-generated data. Similarly, the analysis of wind turbine data is exposing some of the flow physics related to flow separation and loading on the blades, and eventually to noise generation. Two graduate and four undergraduate students are involved in these projects under my direct supervision. Active collaborations include other students in Prof. Glauser’s group, as well as colleagues at the Université de Poitiers.

Teaching Interests:

  • Engineering science fundamentals
  • Fluid mechanics
  • Cognitive development and mind mapping

Each generation of students comes with a different mind set and tool kit. As a teacher, I have to strike a balance between passing on my knowledge (mind set, tool kit) while keeping up to date (new tools) and recognizing that the future belongs to the students more than to me. Regardless of course content, it is my responsibility to set standards and to help the students meet them. I need to share my knowledge while being respectful of the changes taking place in the profession and in society. I have had the mixed blessings of a multidisciplinary background (engineering physics, aerospace, chemical and mechanical engineering) and of teaching a very wide range of topics, which are reflected in broad connections between concepts and methods I share with students.

This philosophy of teaching is currently applied to core engineering science and some graduate courses. To the extent possible in large classes, I try and pay attention to individual students. The elusive goal is to understand how they think, collectively and individually, so I can be more effective in helping each one be his or her best.

Honors:

  • 2004 Lewis F. Moody Award, Division of Fluids Engineering, ASME, “for the most outstanding original paper dealing with the practice of fluid engineering”.
  • 3-time recipient, FilterTech, Pi Tau Sigma and Sigma Gamma Tau award for Excellence in Education in Mechanical and Aerospace Engineering

Courses Taught:

  • MAE 341
  • MAE/CEN 643
  • ECS222
  • MAE545
  • MAE741

Selected Publications:

2012, “Properties of the far-field pressure signatures of individual jet noise sources”, Int. J. Aeroacoustics, 11,651-674.

2007,”Wavelet Transforms”, Section D2 2 .6,Springer Handbook of Experimental Fluid Mechanics (Tropea, Yarin & Foss, Eds.), Springer.

2003, “Effect of unsteady wake passing frequency on boundary layer transition, experimental investigation and wavelet analysis”, J. Fluids Engineering 125, 251-266.

2000, “A filtering and wavelet formulation for incompressible turbulence”, J. of Turbulence 1, 004, 1-16.

1998, “Formal improvements in the solution of the wavelet-transformed Poisson and diffusion equations”, J. Math. Phys. 39, 41 19-4128

1997, “Hamiltonian Formulation for the Diffusion Equation”, Phys. Rev. E 55, 1590- 1599