Wave propagation in periodic media and dispersive effects
- ๐ค Speaker: Grรฉgoire Allaire, Ecole Polytechnique ๐ Website
- ๐ Date & Time: Friday 27 March 2015, 15:00 - 16:00
- ๐ Venue: CMS, MR13
Abstract
We study high frequency wave propagation in a periodic medium for times long enough so that dispersive effects are important. In other words, we consider the homogenization of the wave equation in a periodic medium for long times of the order of the inverse of the period, and for inital data that are Bloch wave packets, i.e. that are the product of a fast oscillating Bloch wave and of a smooth envelope function. We prove that the solution is approximately equal to two waves propagating in opposite directions at a large group velocity with envelope functions which obey a Schrodinger type equation. Our analysis extends the usual WKB approximation by adding a dispersive, or diffractive, effect due to the non uniformity of the group velocity which yields the dispersion tensor of the homogenized Schrodinger equation. This is a joint work with Mariapia Palombaro and Jeff Rauch.
Series This talk is part of the Geometric Analysis & Partial Differential Equations seminar series.
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Friday 27 March 2015, 15:00-16:00