Horizontal momentum and kinetic energy loss of airflow near the surface of sandy beds

In a blowing-sand system, the wind provides the driving forces for particle movement while the moving particles exert an opposing force on the wind by extracting its kinetic energy and momentum to sustain their motion. This extraction of kinetic energy and momentum by the moving particles can be characterized by the magnitude and rate of kinetic energy and horizontal momentum loss. In this study, we used the adaptation of wind velocity profiles to the movement of blowing sand based on the experimental data in a wind tunnel for different grain sizes and at different free-stream wind velocities, calculated the kinetic energy and horizontal momentum loss. The results suggest that the kinetic energy and horizontal momentum loss both increase with increasing height from the surface to a certain height, and then decrease with increasing height. In addition, both factors increase with increasing free-stream wind velocity, and decrease with increasing sand size.