Partial differential equations posed on surfaces arise in mathematical models for many natural phenomena:  diffusion along grain boundaries, lipid interactions in biomembranes, pattern formation, and transport of surfactants on multiphase flow interfaces to mention a few. Numerical methods for solving PDEs posed on manifolds recently received considerable attention. In this talk we review some existing approaches and focus on an Eulerian finite element method for the discretization of elliptic and parabolic partial differential equations on surfaces which may evolve in time. The method uses traces of volume finite element space functions on a surface to discretize equations posed on the surface. The approach is particularly suitable for problems in which the surface is given implicitly by a level set function and in which there is a coupling with a problem in a fixed outer domain. If the surface evolves, then we employ space-time finite elements for a space-time weak formulation of a surface PDE problem. The talk presents analysis and demonstrates results of numerical experiments.
 

I will discuss the homogenization of periodic oscillating Dirichlet
boundary problems in general domains for second order uniformly elliptic
equations. These problems are connected with the study of boundary layers
in fluid mechanics and with the study of higher order asymptotic expansions
in interior homogenization theory. The talk will be aimed at a general
audience. I will explain some recent progress about the continuity
properties of the homogenized problem which displays a sharp contrast
between the case of linear and nonlinear interior equations. This is based
on joint work with Inwon Kim.

We prove that Alexandrov's conjecture relating the area and diameter of a convex surface holds for the surface of a general ellipsoid. This is a direct consequence of a more general result which estimates the deviation from the optimal conjectured bound in terms of the length of  the cut locus of a point on the surface. We also prove that the natural extension of the conjecture to general dimension holds among closed convex spherically symmetric Riemannian manifolds. Our results are based on a new symmetrisation procedure which we believe to be interesting in its own right.

This is joint work with Pedro Freitas accepted for publication in the Tohoku Mathematical Journal, preprint on http://arxiv.org/abs/1406.0811.

We study the holomorphic embedding problem from a compact real algebraic hypersurface into a shpere. By our theorem, for any integer $N$, there is a family of compact real algebraic strongly pseudoconvex hypersurfaces in $C^2$ , none of which can be locally holomorphically embedded into the unit sphere in $C^N$.  This shows that the Whitney (or Remmert) type embedding theorem in differential topology(or in the Stein space theory, respectively) does not hold in the setting above. This is a joint work with Xiaojun Huang and Xiaoshan Li.