He was a theoretician in fluid mechanics, never forgetting the practical applications, in a seamless path from nature to theory to the real world.

He had long-lasting interactions with people in our changing-name Institute, and in the dialogue between Francesco Tampieri and Silvia Trini Castelli some particular facets appear.

STC: Francesco, Julian was a scientific guide and a friend for you, wasn’t he?

FT: Yes. I began working with Julian at the beginning of the eighties. That time he was Fellow of the Trinity College in Cambridge, and he introduced me in DAMTP (Dept of Applied Math and Theoretical Physics): his first gift to me was the understanding that the turbulence lies with full merit under the mantle of theoretical physics, very useful in those years to live in the Bologna University Physics environment.

And what about you, Silvia?

STC: I met him the first time when I was a PhD student, at the “EUROMECH COLLOQUIUM on Atmospheric Turbulence and Dispersion in Complex Terrain”, which you organised in Bologna in September 1995. I was thrilled and honoured at the same time, for his presence in the audience, considering it was my first presentation at a congress… and knowing how severe his questions could be! He was friendly to us, young researchers, and gave us a fundamental lesson: before starting your own study, dig into the past literature, spend all the time needed and learn from it. I am not sure I have been able to comply with it, but I still keep it in my mind anytime I am interested in a new topic.

FT: about talks and conferences, it is worth remembering his transparencies (a geological era ago): so often Julian added in real time a sketch, an equation (or better, just a term of an equation, everyone shall imagine the leftover): every transparency a record of his deep and complex thinking.

Silvia, tell me your feelings about Julian’s lectures.

STC: I remember well his talks at conferences, and his hand-made transparencies dense with formulas and figures, which clearly showed his genius, sometimes making our understanding hard… but always pleasant!

FT: there was a story about Julian, and I can’t rule out that it was used to disapprove his way of reasoning: in the morning, during a briefing about some data, Julian formulates a theoretical interpretation; further data are presented, they disagree with the theory, and in the afternoon Julian presents a novel theoretical interpretation.  Far from being a rough and approximate approach, this story teaches me that a true scientist must face the Nature, any theoretical model may have bugs, and to explain the world you must be ready to supersede your previous beliefs.

He synthesised this way of working with a “very colonial (his words) proverb”: slowly slowly get the monkey. He was born in India, yes.