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

Area of Science:

• Atmospheric Science
• Fluid Dynamics
• Wind Engineering

Background:

• Simulating atmospheric boundary layers is essential for wind engineering.
• Previous methods often lack sufficient depth or accurate representation of stable flow characteristics.

Purpose of the Study:

• To investigate the simulation of horizontally homogeneous boundary layers with stable atmospheric flow characteristics.
• To assess the accuracy of simulated flow above the surface layer using first- and second-order moments of velocity and temperature.

Main Methods:

• Utilized 'flow generators' to create deep boundary layers in a wind tunnel.
• Employed a uniform and non-uniform inlet temperature profiles to study their effects on flow stability.
• Monitored velocity and temperature moments to evaluate flow characteristics.

Main Results:

• Closely horizontally homogeneous flow was achieved, with profiles comparable to atmospheric data.
• Demonstrated that a non-uniform inlet temperature profile requires careful specification to avoid anomalies.
• Found that the ratio of boundary-layer height to surface Obukhov length and surface heat flux are functions of the bulk Richardson number, independent of horizontal homogeneity.

Conclusions:

• The simulation method provides a reliable approach for studying stable atmospheric boundary layers.
• Careful specification of inlet conditions is critical for accurate simulation of stable atmospheric flow.
• The findings offer valuable insights for improving wind engineering practices and atmospheric modeling.