Granular materials like sand typically exist inside of a fluid like air or water. If this fluid is in motion, it will exert forces on the grains and in that way create a particle flux. This transport of granular material is responsible for the formation of dunes and beaches. The first to systematically study airborne sand transport was the British brigadier R. Bagnold who, during the time of World War II did experiments in wind channels and field measurements in the Sahara. He presented the first expression for the sand flux as function of the wind velocity. Since then more refined expressions have been proposed. Bagnold also described for the first time the two basic mechanisms of sand transport: saltation and creep, and wrote the classic book on the subject which still is consulted very much [1].