In this paper we investigate the thermal behaviour of an assembly of consecutive cylinders in a counterrotating
configuration cooled by natural convection with the objective of maximizing the heat transfer density
rate (heat transfer rate per unit volume). A numerical model is used to solve the governing equations that
describe the temperature and flow fields. The spacing between the consecutive cylinders is optimised for each
flow regime (Rayleigh number) and cylinder rotation speed. It was found that the optimized spacing
decreases as the Rayleigh number increases and the heat transfer density rate increases, for the optimized
structure, as the cylinder rotation speed is increased. Results further show that there is an increase in the heat
transfer density rate of the rotating cylinders over stationary cylinders.