Bagnold formula
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The Bagnold formula, named after Ralph Alger Bagnold, relates the amount of sand moved by the wind to wind speed. It states that the mass transport of sand is proportional to the third power of the friction velocity. Under steady conditions this implies that mass transport is proportional to the third power of the wind speed at any fixed height over the sand surface. The formula was derived by Bagnold [1] in 1936 and later published in his book The Physics of Blown Sand and Desert Dunes [2] in 1941. Wind tunnel and field experiments suggest that the fourmula is basically correct. It has later been modified by several researchers, but is still considered to be the benchmark formula.[3][4]
In its simplest form Bagnold's formula may be expressed as:
where q represents the mass transport of sand, C is a dimensionless constant, ρ is the density of air, g is the local gravitational acceleration and u * is friction velocity.
[edit] References
- ^ Bagnold, R.A. 1936. The movement of desert sand. Proceedings of the Royal Society of London A 157(892):594-620.
- ^ Bagnold, R.A. 1941. The physics of blown sand and desert dunes. London: Methuen, 265 pp.
- ^ Greeley, R. and Iversen, J.D. 1985. Wind as a Geological Process, pp. 99 - 100, Cambridge University Press, Cambridge UK.
- ^ Sørensen, M. 2004. On the rate of aeolian sand transport. Geomorphology 59:53-62.
