Thu, 15 Jun 2006

14:00 - 15:00
Comlab

Numerical simulation of flows with strong density imhomogeneities

Dr Jocelyn Etienne
(University of Cambridge)
Abstract

Strong horizontal gradients of density are responsible for the occurence of a large number of (often catastrophic) flows, such as katabatic winds, dust storms, pyroclastic flows and powder-snow avalanches. For a large number of applications, the overall density contrast in the flow remains small and simulations are carried in the Boussinesq limit, where density variations only appear in the body-force term. However, pyroclastic flows and powder-snow avalanches involve much larger density contrasts, which implies that the inhomogeneous Navier-Stokes equations need to be solved, along with a closure equation describing the mass diffusion. We propose a Lagrange-Galerkin numerical scheme to solve this system, and prove optimal error bounds subject to constraints on the order of the discretization and the time-stepping. Simulations of physical relevance are then shown.

Thu, 15 Jun 2006
12:00
SR1

TBC

Christian Gonzalez-Martinez
(Oxford)
Fri, 09 Jun 2006
16:30
L2

Mathematics, mechanics and motility

Prof L Mahadevan
(Harvard, USA)
Abstract

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Fri, 09 Jun 2006
10:00
DH 3rd floor SR
Thu, 08 Jun 2006
16:30
DH 1st floor SR

A teleparallel reformulation of Dirac's equation or quantum electrodynamics for dummies

Dimitri Vassiliev
(University of Bath)
Abstract
The price we pay for this simplicity is that the change of variable
spinor --> coframe
makes the Dirac equation nonlinear. The morale of the talk is that, in our opinion, it is more natural to view the Dirac equation as a nonlinear equation for the unknown coframe rather than a linear equation for the unknown spinor.