Self-propulsion of rotating axisymmetric particles at intermediate Reynolds number

In this talk, we discuss the dynamics of an axisymmetric particle rotating in a quiescent fluid. At zero Reynolds number, time-reversal symmetry implies such a particle does not move regardless of its boundary profile. For nonzero Reynolds numbers, however, we find head-tail asymmetry in the particle can cause it to self-propel. Combining laboratory experiments, numerical simulations, and boundary layer analysis, we examine the role of geometry on propulsion, focusing in particular on conical particles. We identify scaling laws in the propulsion speed as a function of the rotation frequency and various geometric factors, and show these laws have their origin in boundary layer flows. Finally, we discuss the collective dynamics of suspensions of rotating particles.