This project investigated how ribbed or roughened surfaces improve heat transfer within fluid channels. This principle can be applied directly to cooling systems in nuclear reactor components.

Using advanced computational fluid dynamics (CFD), the study compared detailed three-dimensional (3D) models of ribbed channels with simplified two-dimensional (2D) models. The aim was to assess whether 2D simulations could provide accurate results with less computational time and cost.

The project also explored how different thermal boundary conditions and near-wall treatments affected heat transfer and flow patterns.

The findings showed that 2D simulations could accurately represent the core flow behaviour of 3D rib-roughened channels without a significant loss of accuracy. This is particularly valuable in nuclear thermal-hydraulic analysis, where computational efficiency is important for safety assessment and design optimisation.

The thermal conditions applied to the ribs, whether heated or insulated, had only a minor effect on overall heat transfer. However, they did influence local temperature gradients around the ribs.

The choice of turbulence model and near-wall treatment proved more significant. Low-Reynolds-number models captured complex flow separation and reattachment more accurately than high-Reynolds-number models using standard wall functions.

These findings are especially relevant to the design of fuel assemblies and coolant channels in advanced gas-cooled reactors (AGRs) and next-generation nuclear systems.

The study provides engineers with a more efficient way to model turbulent heat transfer while maintaining accurate predictions of temperature and flow fields. This could help improve thermal performance, reactor safety and component longevity.