I don't know, but it looks like there is some circular object in there with a different refractive index. And you can see "whispering gallery" modes trapped along surface...
--- On Mon, 16/5/11, brian whatcott <betwys1@sbcglobal.net> wrote:
From: brian whatcott <betwys1@sbcglobal.net>
Subject: [Phys-l] CFD Visualization - Microwave Oven
To: "Forum for Physics Educators" <phys-l@carnot.physics.buffalo.edu>
Date: Monday, 16 May, 2011, 18:12