Preliminary DNS results of friction factor at low Re inside a rectangular channel with 1:10 Aspect Ratio

A numerical and experimental study is carried on to investigate the fluid-dynamical performanced of a smooth duct with Aspect Ratio of 10. The flow Reynolds number is between 470 and 14500, computed over the duct hydraulic diameter, ranging from laminar to turbulent flow. Direct Numerical Simulations are performed, to explore the details of all flow scales, by means of a code developed at Politecnico di Milano. The presented numerical results include the computation of the friction factor and the identification of the transition from laminar to turbulent flow regime, and reproduce experimental and literature data fairly well. The setup of the described numerical and experimental techniques will allow to carry on a detailed investigation of the fluid-dynamical and thermal performances of ribbed duct.