Direct numerical simulation of curved turbulent channel flow

Low Reynolds number mildly curved turbulent channel flow has been simulated numerically without subgrid scale models. A new spectral numerical method developed for this problem was used. The computations were performed with two million degrees of freedom. A variety of statistical and structural information has been extracted from the computed flow fields. These include mean velocity turbulence stresses, velocity skewness and flatness factors, space time correlations and spectra, all the terms in the Reynolds stress balance equations, and contour and vector plots of instantaneous velocity fields. The effects of curvature on this flow were determined by comparing the concave and convex sides of the channel. The observed effects are consistent with experimental observations for mild curvature. The most significant difference in the turbulence statistics between the concave and convex sides was in the Reynolds shear stress. This was accompanied by significant differences in the terms of the Reynolds shear stress balance equations.