Vortex-induced vibration of solid structures has been known since ancient times, and remains a very important problem of fluid mechanics. Experimental studies of the vortex-induced vibration of circular cylinders have provided many fundamental insights. Recent extremely carefully controlled forced vibration experiments by Morse & Williamson (J. Fluid Mech., 2009, this issue, vol. 634, pp. 5–39), generating finely resolved data sets, are providing a fresh understanding of the mechanisms involved, especially for ocean structures with very low mass and damping.

Recent work has developed a beautiful model system for studying the energy focusing and heating power of collapsing bubbles. The bubble is effectively one-dimensional and the collapse and heating can be quantitatively measured. Thermal effects are shown to play an essential role in the time-dependent dynamics.

Turbulent flows near walls have been the focus of intense study since their first description by Ludwig Prandtl over 100 years ago. They are critical in determining the drag and lift of an aircraft wing for example. Key challenges are to understand the physical mechanisms causing the transition from smooth, laminar flow to turbulent flow and how the turbulence is then maintained. Recent direct numerical simulations have contributed significantly towards this understanding.