Motility of micro-organisms in fluids plays vital roles in diverse biological processes. The physics governing their locomotion at low Reynolds numbers in Newtonian fluids is relatively well studied. However, many biological fluids, such as blood, respiratory and cervical mucus, display complex (non-Newtonian) rheological properties including viscoelasticity and shear-thinning viscosity. An understanding of the effects of complex rheology on locomotion is still developing. The fundamental question whether these nonlinear rheological properties enhance or hinder locomotion at small scales has attracted considerable recent interests. In this talk, we will consider different idealized models to elucidate the influence of complex rheology on locomotion at low Reynolds numbers, as well as their implications on the design of synthetic micro-swimmers.

On Shun Pak is currently an Assistant Professor in Mechanical Engineering at Santa Clara University, CA, USA. On Shun obtained his Bachelor of Engineering in Mechanical Engineering from the University of Hong Kong in 2008 and completed his Ph.D. with Eric Lauga at the University of California, San Diego in 2013. He then continued his research as a Postdoctoral Research Fellow with Howard Stone at Princeton University, before joining the Department of Mechanical Engineering at Santa Clara University in 2014. On Shun has received a Siebel Scholar Award in Bioengineering (Class 2013). His research interests include low Reynolds number flows, biological fluid mechanics, and complex fluids.