Roughness-triggered turbulent boundary layers in Rayleigh-Bénard convection

We present measurements carried out inside the Barrel of Ilmenau as part of the European EuHIT transnational infrastructure access program. The Barrel of Ilmenau is the worldwide largest experiment to study highly turbulent convection in air. A rectangular cell, with proportions strictly identical to the water cell in Lyon [Salort, et al. PoF 26:015112 (2014)], but six times larger, has been inserted inside the Barrel. The top plate is smooth, and the bottom plate is rough. The roughness are also similar to the one in Lyon, but six times larger. We have obtained velocity fields using PIV near the obstacles, as well as the local heat-flux on the bottom plate. This has allowed us to test and improve our previous interpretation of the roughness-induced heat transfer enhancement mechanisms