I am interested in strongly nonlinear flows involving many length scales. Very often these phenomena are characterised by the underlying (hydrodynamic) equations becoming singular. The structure of singular solutions is typically self-similar, i.e. profiles observed on different scales can be mapped onto each other by rescaling the axes. Examples are the formation of drops, drops spreading on a solid substrate, or singular surface deformations caused by a jet falling into a pool liquid. Understanding the structure of singularities is crucial for modelling industrial processes such as printing, coating, or the entrainment of air into liquids.