Renzo Luigi Ricca (24 January 1960) is an Italian-born applied mathematician (naturalised British citizen), professor of mathematical physics at the University of Milano-Bicocca.

By a prestigious doctoral grant offered by the Association for the Promotion of the Scientific and Technological Development of Piedmont (ASSTP, Turin) he entered Trinity College at the University of Cambridge, where he read mathematics.

Ricca's main research interests lie in ideal fluid dynamics, particularly as regards geometric and topological aspects of vortex flows and magnetic fields forming knots, links and braids.

[3] In ideal magnetohydrodynamics Ricca has demonstrated the effects of inflexional instability of twisted magnetic flux tubes[4] that trigger braid formation in solar coronal loops.

In 1992, relying on earlier work by Berger and Field,[6] Moffatt and Ricca [7] established a deep connection between topology and classical field theory extending the original result by Keith Moffatt on the topological interpretation of hydrodynamical helicity[8] and providing a rigorous derivation of the linking number of an isolated flux tube from the helicity of classical fluid mechanics in terms of writhe and twist.

In 2011 he organised a 3-month programme on knots and applications held at the Ennio De Giorgi Mathematical Research Centre of the Scuola Normale Superiore in Pisa.