12:45
Spindles, orbi-bundles, and Seifert fibrations
Abstract
Is it possible to define gauge theories on singular spaces? The answer to this question is emphatically yes, and the prime example of such spaces are two-dimensional orbifolds known as spindles. First, I will introduce spindles from a symplectic geometry perspective. Then I will discuss the notion of orbi-bundles, which allows one to consistently describe regular gauge fields/spinors on orbifolds.
Stabilised Finite Element Methods for General Convection–Diffusion Equations
Abstract
Dr Jindong Wang will talk about; 'Stabilised Finite Element Methods for General Convection–Diffusion Equations'
This talk presents several stabilised finite element methods for general convection–diffusion equations, with particular emphasis on recent extensions to vector-valued problems arising in magnetohydrodynamics (MHD). Owing to the non-self-adjoint structure of the operator and the potentially large disparity between convective and diffusive scales, standard Galerkin discretisations may exhibit non-physical oscillations. We design a class of upwind-type schemes and exponentially fitted methods for vector-valued problems that mitigate these effects, highlighting both their shared stabilisation mechanisms and the distinctive features that arise in the vector-valued setting. These developments illustrate concrete strategies for the design and analysis of finite element discretisations for general convection–diffusion problems.