Experimental and numerical studies of turbulent flow in a non-circular duct with a rough wall are very scarce. Therefore, numerical analysis has been carried out in this study for fully developed turbulent flow in a square duct with a roughened wall using the Reynolds stress model. Calculated results are compared with the experimental data available. The present method can predict well a large eddy caused by the secondary flow of the second kind in a half cross section and a small eddy is observed in the upper wall corner region. However, a small eddy which appeared in the calculated results is not recognized in the experimental data. Calculated results of normal stresses and turbulent energy are in comparatively good agreement with the experimental data. These examinations suggest that the present method utilizing the Reynolds stress model, which is classified by an anisotropic turbulent model of high Reynolds number, is able to predict the turbulent flow in a square duct with roughened walls.
