The weather is finally starting to warm up, and people are breaking out the shorts, bathing suits and flip-flops.

The dyes which are injected into the skin to create tattoos move with time – permanently altering the look of a given design. In this month’s Mathematics Today Dr Ian Eames, a Reader in Fluid Mechanics at UCL, publishes a mathematical model enabling us to estimate the movement of these ink particles and predict how specific tattoo designs will look several years in the future.