Obituary: José Manuel Redondo Apraiz

13 October 2020

José Manuel Redondo Apraiz was an avid experimentalist in everything, including physics of fluids, languages, cuisine, and even human relations.

After completing his PhD in 1989 in Cambridge, UK, he kept a quasi-permanent invited professorship there and made many visits to DAMTP over the following 30 years. After a postdoctoral period in DAMTP, he was appointed to a professor position in the department of Física Aplicada at Universitat Politècnica de Catalunya – UPC Barcelona, where he found a stimulating environment, especially in coastal oceanography and satellite imaging in relation to the European Space Agency.

He developed strong and continuous collaborations with worldwide recognized research teams, contributing to research groups like ERCOFTAC, organizing a number of international conferences, sessions, and summer schools and acting as an editor in numerous international special issues.

He had been generous with his time for the hustle and bustle of the EGU Division of Nonlinear Processes in Geosciences: he created and chaired its subdivision on turbulence, and he also acted as topical editor of the journal Nonlinear Processes in Geophysics.

At UPC José conducted experiments with significant contributions to turbulent mixing and entrainment, including Richtmyer–Meshkov and Rayleigh–Taylor instabilities, and in other areas with applications to environmental flows such as plumes, wakes, and jets. One of José’s main contributions was the use of multifractal analysis, and, from the days of his PhD, he was an early proponent of the use fractal dimensions to characterize interfaces in turbulent flows, an approach that has since been widely adopted.

Turbulence was his main field of interest, but in fact, he was really a metaphor of turbulence. Indeed, his behaviour appeared random, chaotic, nonlinear, and poorly predictable, but in the end his mean production was impressive with a significant rms value. He was used to mixing or switching subjects and the many languages he spoke.

As a physicist, he was able to develop relevant setups from simple everyday materials such as water basins, pieces of paper, rakes, and brooms to demonstrate the effect of rotation and stratification on diffusion of particles, up to sophisticated laboratory setups performing advanced PIV and multifractal-analysis-based software. Such original tools were adapted to shape recognition of clouds, marine vortices, or oil spills. He also worked on the influence of turbulence on plankton distribution.

Educated in mathematics and physics but also in many other areas, José was also a great theoretician who was able to connect different branches of science, including physics and biology. He was also able to provide advice on numerical modelling.

As the son of a sailor, José loved the sea and mostly applied his research activity to marine science. He represented Spain, swimming butterfly as a young man. He jumped and swam in any pool like a former Olympic champion, but he was also the dolphin you could observe any time offshore Vilanova y la Geltrú, the place he lived and fished to make homemade paella, where he could observe wildlife and watch clams bubble in the sand for hours.

José did not pay too much attention to usual rules, concepts, and covenants. He mixed his personal and professional life and time, disregarding frontiers and borders. He was always on the go, day and night: travelling, lecturing, studying, and reading books at any time, sleeping when possible and living in a state of permanent jet lag.

José was very adaptable and, in this way, impregnable even by the traffic police. He could accurately answer questions you asked him on any subject, but this could necessitate some delay, up to years if he needed some new insights or needed to perform new experiments.

José Manuel Redondo Apraiz was a bright scientist, sometimes mildly confrontational, but provided constructive criticism and most often suggested new ideas, all while maintaining a friendly attitude. He had an appealing personality and generously helped and advised scores of young scientists.

Overall, he was a great friend and a scientist.

Philippe Fraunié, Paul Linden, Daniel Schertzer, François Schmitt