Abstract
Barchan dunes can be found in sand barren regions under steady wind conditions. They translate in the direction of the wind while their shape remains unchanged. They have a minimal length in the order of ten meters, which renders laboratory experiments almost impossible. The length scale is set by the details of the sand-wind interaction. Smaller dunes do not evolve into the typical barchan dune shape. Our experimental approach produces dramatically scaled down barchan dunes. The idea is to modulate gravity by vertical oscillation of the sand bed. We produce small dunes that travel in the turbulent boundary layer of an open windtunnel. Particle image velocimetry on the surface of moving dunes reveals the flux of creeping sand, while measurement of sand grains flying through the air quantifies the key mechanism that moves sand by wind: saltation. While the amount of sand flying with the flow does not vary strongly in an oscillation cycle, the sand creeping over the dune surface is only in motion when the effective gravity is smaller than g. Thus, modulation of gravity provides a unique view on sand transport in wind. Saltation is an activation process, and we demonstrate the importance of turbulence.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2008.DFD.AV.10
Original language | English |
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Title of host publication | Proceedings of the 61st Annual Meeting of the APS Division of Fluid Dynamics, San Antonio, Texas, USA, 23-25 November, 2008 |
Place of Publication | San Antonio, USA |
Publication status | Published - 2008 |
Event | 61st Annual Meeting of the APS Division of Fluid Dynamics (DFD08), November 23-25, 2008, San Antonio, TX, USA - San Antonio Convention Center, San Antonio, TX, United States Duration: 23 Nov 2008 → 25 Nov 2008 http://www.aps.org/meetings/meeting.cfm?name=DFD08 |
Conference
Conference | 61st Annual Meeting of the APS Division of Fluid Dynamics (DFD08), November 23-25, 2008, San Antonio, TX, USA |
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Abbreviated title | DFD08 |
Country/Territory | United States |
City | San Antonio, TX |
Period | 23/11/08 → 25/11/08 |
Internet address |