**Date & Time:** Thursday, 4th Mar, 2010 16:00-17:00.

**Venue:** Ramanujan Hall, Mathematics Department

**Title:** Nonlinear acoustical guided waves

**Speaker:** Dr. Francois Coulouvrat, University of Paris

**Abstract:**
Noise reduction is an important issue for aircraft industry. This work
investigates the fundamental of so-called « Buzz-saw Noise » (BSN) due
to shock waves emanating from the tip of engine fan blades when
rotating at supersonic speeds. Based on a linear modal expansion with
varying amplitudes, we show how to reduce a nonlinear partial
differential equation to a system of ordinary differential equations.
This quasi modal model will then be illustrated to two simple
geometries : a 2D one and a 3D one. The 2D geometry will help
illustrate the notion of dispersive or non dispersive interations. The
3D case will explain the observed characteristics of BSN.