Complex fluids such as polymer and surfactant solutions exhibit a rich variety of nonlinear rheological behavior. Under particular flow conditions, instabilities like shear banding, wall slip, elastic turbulence, and beads on a string can develop. Projects in this area focus on understanding how fluid microstructure, macromolecular size, and ionic environment influence the presence and evolution of these flow instabilities.

Some complex fluids exhibit shear banding flow instabilities, where discontinuous velocity profiles across the rheological geometry result in bands of distinct shear rate, viscosity, and structure.