Ian Wilson, University of Cambridge

A Stefan-Graetz problem in the kitchen: cleaning by convective dissolution

Thursday 12 February 2026, 11:30-12:30

One method of removing layers of unwanted material from a surface is to contact it with a solvent in which it will dissolve. The rate of dissolution is enhanced when the solvent is flowing, which is why dishwashers spray liquid around to both contact soiled plates with the aqueous cleaning solution and to generate falling films over the surfaces. [This is also why you should stack the dirty dishes properly!] In many cases a cleaning front develops, between soil-free and soiled regions. Modelling the front dynamics – a Stefan problem – is complicated by the rate of mass transfer being spatially non-linear – the Graetz problem. In this talk I will present recent experimental and numerical work on this topic, driven by an interest to improve the sustainability of cleaning-in-place of food processing equipment. No food will be cleaned during this talk, just lots of instant coffee.