Wall-bounded turbulent flows under smooth- and rough-wall surface conditions were measured using particle image velocimetry (PIV) in the Atmospheric Boundary Layer Wind Tunnel at St. Anthony Falls Laboratory (SAFL), University of Minnesota. In the rough-wall case, the tunnel surface was covered with woven wire mesh. The smooth- and rough-wall conditions were each measured for two free-stream velocities (7 m/s and 10 m/s), totaling four flow cases. The friction Reynolds number in the four cases ranges from 3,800 to 14,000. In each case, the PIV imaging field was oriented in the streamwise–wall-normal plane. To enhance the spatial resolution, the measurement field was positioned in the lowest 10 cm of the boundary layer, capturing the roughness sublayer and logarithmic region in the rough-wall cases. Separate high-frequency hotwire anemometer measurements of the full boundary layer profile were used to estimate the scaling parameters such as the boundary layer thickness. This dataset includes the processed velocity vector fields from the PIV measurements and the key scaling parameters.
Data files: The data are provided in the MATLAB data file format (.mat), with a separate set of files for each flow case. The files are named based on the surface (i.e. smooth or mesh) and free-stream velocity (i.e. 7 m/s or 10 m/s) for the given case. The smooth-wall velocity vector files each contain vectors for 10,000 PIV frames. The rough-wall velocity vector data are separated into two files – each with 5,000 PIV frames – based on the position of the laser within the roughness pattern. See the File_Description document for the laser positioning, definitions for each variable in the data files, and an overview of the flow parameters. Woven wire mesh: The mesh had 3 mm diameter and 25 mm opening size, i.e. distance between wires. The mesh height above the wind tunnel floor varied from 3 mm to 6 mm based on the overlapping, woven wires. The wire mesh covered the test section and the 16 m between the wind tunnel contraction and test section. See the File_Description document for a photo of the woven wire mesh. PIV system: The PIV equipment included a Big Sky 532 nm Nd:YAG double-pulsed laser, a TSI Powerview 4 MP camera, and TSI Insight 4G synchronizer and acquisition software. The raw images were processed using in-house cross-correlation code with two passes and 50% vector overlap. The measurements are not time-resolved.