Looking for marginally trapped surfaces
K. P. Tod · Classical and Quantum Gravity · 1991
Two flows are described which evolve an initial spherical 2-surface on a given spacelike hypersurface to one or more minimal 2-spheres or to a point. These flows can be used to seek marginally-trapped 2-spheres on an umbilic 3-surface and simple modifications of them can be used for the same purpose on a 3-surface with non-vanishing second fundamental form.