Kristian Thijssen - Control of Active Nematics

Coupling between flows and material properties imbues rheological matter with its wide-ranging applicability, hence the excitement for harnessing the rheology of active fluids for which internal structure and continuous energy injection lead to spontaneous flows and complex, out-of-equilibrium dynamics. In this talk, I will discuss work investigating different ways to control active nematic films indirectly by altering substrate properties. The effect of isotropic and anisotropic friction is discussed on the active nematic film's general flow and topological structure. I will also propose and demonstrate a convenient, highly tuneable method for controlling flow, topology and composition within active nematic films due to the indirect presence of fully submersed micropatterned structures within a thin, underlying oil layer. Simulations reveal that micropatterned structures produce effective virtual boundaries within the superjacent active nematic film due to differences in viscous dissipation as a function of depth. These accessible methods of applying effective dissipation to the active films present a non-intrusive pathway for engineering active microfluidic systems.