Since its foundation over 50 years ago, by George Batchelor, Journal of Fluid Mechanics has published theoretical, computational and experimental investigations on all aspects of the mechanics of fluids. Over this time, the research community of talented scientists, engineers and mathematicians contributing to the astonishing development of our understanding of fluid flow has grown enormously.

This growth has naturally been reflected in the growth of the journal. In 1956 there were 39 papers published in a single volume of 672 pages, while in 2008 there were 450 papers, extending over nearly 11000 pages and 24 volumes. The array of topics considered has similarly broadened hugely, as a quick scan of the titles of the papers can verify.

Building on traditional fields such as aerodynamics, geophysical flows and wave phenomena, research into fluid dynamics has spread into new and exciting areas such as biological flow, granular media, and flows on extremely small physical and time scales.

With all this research output, it is becoming an increasing challenge to keep abreast of the development of the field as a whole, and indeed to identify emerging areas and connections between sub- subjects. This is particularly true for non-specialists in the many other scientific disciplines where fluid mechanics research is highly significant, and has the potential to make critical contributions to advances, if only the importance of the research can be identified and interpreted.

Therefore, Cambridge University Press and the Editorial Board of the Journal have decided to institute a new Focus on Fluids section. Every month, one particularly interesting published paper will be the subject of an extended review and discussion by an acknowledged and invited expert in the field. The Focus on Fluids article will explain the context, importance and implications of the underlying paper to a wider scientific audience, highlighting both the key findings and breakthroughs of the paper and the implications of the research for future activity.

The Focus on Fluids article will appear both in the print journal, and as a free online pdf on Cambridge Journals Online. Authors are welcome to propose that their papers are featured in this section by contacting the associate editor responsible, Dr C. P. Caulfield. Through this initiative, we hope to raise the visibility of fluid mechanics research and attract more people to this beautiful, challenging and increasingly relevant subject.