Rough surfaces generate complex turbulent structures in wall-bounded flows. These structures are known to enhance the transport of momentum and heat, but to date they have eluded precise physical prediction of their effect of heat transfer. This knowledge gap prevents the optimal design of countless technical systems, from internal combustion systems to heat exchangers.
Existing experimental studies are limited to point measurements or global averages of heat flow. The question of which specific flow structures control heat flow in rough, turbulent boundary layers remains unanswered.
Therefore, we aim to investigate the direct, spatially high-resolution correlation between the turbulent flow field and the two-dimensional heat flow patterns on a rough wall for the first time experimentally.
To decipher this physical coupling, a multimodal measurement approach is being pursued: i) the local heat flow is investigated in high spatial resolution using infrared thermography; ii) the flow field is to be measured using optical techniques and hot-wire anemometry.
The experimental data will be compared with results obtained through high-fidelity direct numerical flow simulations in which heat transfer is often modelled as a passive scalar.  In addition, the collected data set will be helpful to develop and refine wall models for rough surfaces, which will enable more reliable and accurate predictions of heat transfer in technical applications in the future.