Transitional behaviour of saltation: wind tunnel observations of unsteady winds Original Research Article

Aspects of the transitional behaviour of aeolian saltation are investigated in a wind tunnel using non-intrusive, high frequency (≈25 Hz) optical detection of sand transport. The experiments were conducted in concert with the development of a numerical model of sand transport in unsteady winds by Spies and McEwan. Comparisons are made with model outcomes and with data collected using a sand trap equipped with a sensitive load cell. A programmable velocity control was used to generate reproducible velocity excursions and sinusoidal gust sequences. For velocities less than ≈8·0 m s−1the performance of the wind tunnel meets the recommended value of the independence Froude number.