Henry Shum

The area of my DPhil research is bacterial flagellar motion and accompanying microbiological fluid flows. The hydrodynamics at these small scales are governed by Stokes equations and filament motion can be studied using techniques such as resistive force theory and slender body theory. These approximations are often remarkably useful in unbounded fluids  but become less reliable when the fluid flow in the vicinity of a short segment of the flagellum is perturbed significantly by the presence of an external boundary or if curvilinearly distant sections of the flagellum approach each other due to the curve of the flagellum.

In such cases, more accurate (but also more computationally intensive) techniques such as boundary element methods (BEM) can be used instead.  I make extensive use of BEM combined with other numerical code to explore the dynamics of a simple cell propelled by a single rotating flagellum. In particular, the kind of behaviour I am interested in includes how fluid domain geometry or physical parameters such as flagellum length and shape affect motion. Because I perform all my experiments in silico I am interested in general numerical analysis techniques that I can apply to my problem.

Swimming through confined fluids is relevant if we wish to understand how bacteria move around in a host organism and aggregate to cause infections or initiate biofilm formation on immersed substrate surfaces. There is also interest in using bacteria in microfluidic systems and understanding how they behave in these environments is critical to the design of the devices.

Demonstrations have shown that carpets of bacteria fixed to a surface within a fluid chamber can produce long-range fluid flows. It would be interesting to investigate the feasibility of using bacteria in this manner to drive a fluid through the system or enhance fluid mixing with some level of control.