The Multidisciplinary Group CFD@Nottingham is pleased to invite you to attend the following talk on:

"Level Set Methods for Interfacial Flows" Faculty of Engineering, Coates Building, Rm B35 (Civil) 13:00-14:00.

by Peter Spelt Theoretical mechanics School of Mathematical Sciences University of Nottingham

Level set is an efficient numerical method that has been developed over the past 10 years for the simulation of two-phase flows, such as rising bubbles or droplets. The problem with simulating such fluid flows is that the shape and position of the interface between the two fluids (the bubble or droplet surface) are not known a priori (only in specific cases), and have to be solved as part of the problem. Applications of such simulations are in the development for mathematical models for bubbly liquids and suspensions. But the same problem occurs in, for instance, gas flow past a liquid film (common in chemical processing), the generation of waves by wind, tumour and biofilm growth, and the deformation of biological cells in blood flows. Level set provides an efficient way of tracking such interfaces; it is also used in a huge variety of other applications, including computer image enhancement and combustion. In the talk, level set is briefly explained, and how it can be coupled to more or less conventional CFD methods for the simulation of interfacial fluid flows. A problem that is addressed in some detail in the talk is the simulation of fluid flow past a deformable droplet that is adhering to a solid wall. This serves as a model of a cell adhering to the interior side of a blood vessel wall, but it is also relevant for applications in industrial cleaning processes. A complication for this type of two-phase flow is the presence of contact lines (intersections of interfaces with a solid wall), especially if these are not pinned. An extension of a level set approach is proposed, such that flows with moving contact lines can be simulated, and several examples will be shown.