Abstract: | Turbulent flow inside ducts differs significantly from the statistically one‐dimensional turbulent channel flow due to the additional confining lateral walls. Secondary flows in the corners are found which are known to affect the turbulence structure close to the walls. Most computations have been performed for incompressible or only slightly compressible flows and with square duct geometries (e.g. [1,2]). In the present study we address the effect of the aspect ratio on the flow structure in high subsonic rectangular duct flow using LES. Mean‐flow characteristics are analyzed and compared to square duct and channel flow data. We find good agreement with available incompressible DNS square duct data for low Mach number computations. For aspect ratios as high as five, the mean‐flow profile in the center of the longer side of the duct along the wall normal direction differs distinctively from channel flow for the present Mach 0.7 computations. |