A novel concept of rotating circular ribs as artificial roughness has been employed within a two-dimensional rectangular duct to understand their effects on heat transfer and air flow characteristics using CFD. The effects of design parameters such as roughness height, roughness pitch, relative roughness height, relative roughness pitch, and rotational speed of the circular rib are simulated for Reynolds number ranging from 3800 to 18,000 under solar air heater boundary conditions. 54% increase in Nusselt number is observed for rib height of 1.4 mm, pitch of 10 mm, circular rib rotation of 10000 rpm at Re = 3800 as compared with fixed ribs. The maximum thermo-hydraulic performance factor of 1.57 is achieved at Reynolds number of 3800 for the circular ribs—relative roughness height of 0.042 and relative roughness pitch of 25— rotating counter to flow with 10000 rpm. For a given rotational speed of the circular ribs, thermo-hydraulic performance factor decreases at higher flow velocities. Significant increase in Nusselt number with rotating ribs as artificial roughness establishes the potential of this novel approach for solar air heaters. © 2021 Elsevier Ltd