Wind-Tunnel Simulation of Weakly and Moderately Stable Atmospheric Boundary Layers

• Published in: Boundary-layer meteorology Vol. 168; no. 1; pp. 29 - 57
• Main Authors: Hancock, Philip E., Hayden, Paul
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.07.2018; Springer; Springer Nature B.V
• Subjects: Atmospheric boundary layer; Atmospheric data; Atmospheric Protection/Air Quality Control/Air Pollution; Atmospheric Sciences; Boundary layer; Boundary layer height; Boundary layer stability; Boundary layers; Boundary layers (Fluid dynamics); Deep layer; Depth profiling; Earth and Environmental Science; Earth Sciences; Fluid dynamics; Heat flux; Heat transfer; Inlet temperature; Meteorology; Obukhov length; Profiles; Research Article; Richardson number; Simulation; Stability; Surface boundary layer; Surface layers; Temperature effects; Temperature profile; Temperature requirements; Tropospheric circulation; Turbulence; Turbulence (Fluid dynamics); Turbulent mixing; Wind engineering; Wind tunnels; Local similarity; Stable stratification; Wind-tunnel simulation; Atmospheric boundary layer
• ISSN: 0006-8314; 1573-1472
• DOI: 10.1007/s10546-018-0337-7

The simulation of horizontally homogeneous boundary layers that have characteristics of weakly and moderately stable atmospheric flow is investigated, where the well-established wind engineering practice of using ‘flow generators’ to provide a deep boundary layer is employed. Primary attention is given to the flow above the surface layer, in the absence of an overlying inversion, as assessed from first- and second-order moments of velocity and temperature. A uniform inlet temperature profile ahead of a deep layer, allowing initially neutral flow, results in the upper part of the boundary layer remaining neutral. A non-uniform inlet temperature profile is required but needs careful specification if odd characteristics are to be avoided, attributed to long-lasting effects inherent of stability, and to a reduced level of turbulent mixing. The first part of the wind-tunnel floor must not be cooled if turbulence quantities are to vary smoothly with height. Closely horizontally homogeneous flow is demonstrated, where profiles are comparable or closely comparable with atmospheric data in terms of local similarity and functions of normalized height. The ratio of boundary-layer height to surface Obukhov length, and the surface heat flux, are functions of the bulk Richardson number, independent of horizontal homogeneity. Surface heat flux rises to a maximum and then decreases.