Progresses in turbulent Rayleigh-Bénard convection over rough surfaces

Turbulent convection over a rough surface is a common scenario that one often encounters in nature and in many industrial processes. It is of great interest and especially useful to reveal the properties of this type of flow. In this paper, we present an overview of recent progresses in turbulent Rayleigh-Benard convection over rough surfaces, including how surface roughness enhances/reduces the global heat transfer through the system, whether roughness could be used as a route to the ultimate regime of thermal convection. We also point out the main remaining issues and challenges and giving an outlook on the future development. Rough surface to affect the turbulent transport need to further research, based on exquisite measurement of boundary layers. Rough surface causes plumes generating and separating, and at the same time evolution of one-roll state and multi-roll state in the large scale circulation, is seldom studied. Structure of rough surface lead to symmetry influence on flow structure, which requires further probe.