In this work, the turbulent flow was studied in a new SAH (solar air heater) test bench. Particularly, we have considered the natural and the forced convection modes. The used test bench is composed by two passages separated by an absorber and powered by a fan working in a delivery mode, placed in the inlet side the insulation, for the forced convection mode. On this system, a glass is hanging on the front side and an absorber is inserted inside. On the glass side, it is connected to the box prototype through a pipe. The hot air flow is routed towards the box prototype. Two circular holes, are located in the same face of the box prototype. The inlet hole allows the hot air supply. However, the outlet hole allows its escape into the ambient environment. By using the ANSYS Fluent 17.0 software, the Navier-Stokes equations coupled with the standard k-omega turbulence model were solved. The numerical results were compared with our experimental data, established in the second passage of the SAH test bench. The good agreement confirms the validity of the numerical method. The range of temperatures is very useful in many applications such as industrial and domestic applications. (C) 2018 Elsevier Ltd. All rights reserved.