Swimming in complex fluids

This project will address an open problem regarding the locomotion of biological swimmers, a problem of widespread importance throughout the animal kingdom. While many fish swim in water, many biological swimmers locomote through complex, non-Newtonian fluids, often characterized as viscoelastic (such as gels) or viscoplastic (such as mud). In fact, biological swimmers naturally adapt their gait, depending on the medium, to maximise the efficiency of their locomotion. Many microscopic swimmers are long and thin (such as sperm, bacterial flagella, and even microscopic worms), and therefore dubbed slender bodies. To date, slender bodies have been studied in Newtonian, or viscoelastic or viscoplastic fluids. We wish to develop and explore a new set of fundamental analytical and computational tools for slender bodies in complex fluids that combine both elastic and plastic contributions. The first objective would be to be able to characterize the effect of complex fluids on active slender bodies. To advance our understanding of swimming in viscoelasto-plastic fluids, in this project, you will develop mathematical and computational models of complex fluids, combining viscosity, elasticity and plasticity in a single framework. Using analytical, numerical and simulation methods, you will then study fluid dynamics around moving rigid objects, such as rods or sheets, and finally, study the fluid dynamics around long and slender swimming (periodically deforming) objects.