HR: 0800h
AN: P31B-0982    [Abstracts]
TI: Dust Devils: Experimental Results for Vortex Sediment Flux
AU: * Neakrase, L D
EM: neakrase@asu.edu
AF: Dept. of Geological Sciences Arizona State University, Box 871404, Tempe, AZ 85283-1404 United States
AU: Greeley, R
AF: Dept. of Geological Sciences Arizona State University, Box 871404, Tempe, AZ 85283-1404 United States
AU: Iversen, J D
AF: Aerospace Engineering and Engineering Mechanics Dept., Iowa State University, Ames, IA 50011-2271 United States
AU: Balme, M L
AF: Dept. of Geological Sciences Arizona State University, Box 871404, Tempe, AZ 85283-1404 United States
AU: Foley, D J
AF: Dept. of Geological Sciences Arizona State University, Box 871404, Tempe, AZ 85283-1404 United States
AU: Eddlemon, E E
AF: Mars Surface Wind Tunnel NASA Ames Research Center, Mail Stop 212-6, Moffet Field, CA 94035-1000 United States
AB: Laboratory experiments using the {\it Arizona State University Vortex Generator} ("dust devil machine") yield new results in simulating the amount of sand and dust (flux) raised by dust devils. Flux experiments involved measuring mass loss from a test bed as a function of time for known vortex parameters yielding a calculated value for the flux. Sediment fluxes of dust (2 $\mu$m in diameter), silica sands (5 sizes ranging in diameter from 90 to 500 $\mu$m), and walnut shells (2 sizes ranging in diameter from 590 to 1700 $\mu$m) are compared to the Reynold's number, {\it u{$\theta$}r{$\theta$}/$\nu$} (4000-18,000), and a dimensionless lifting parameter, {\it $\Delta$P/($\rho$$_{p}$gD$_{p}$)}, (0.001-1.0), in which {\it u{$\theta$}} and {\it r{$\theta$}} are the vortex tangential velocity and core radius, {\it $\nu$} is the kinematic viscosity of the air, {\it $\Delta$P} is the pressure drop across the vortex, {\it $\rho$$_{p}$} and {\it D$_{p}$} are the particle density and diameter, and {\it g} is gravitational acceleration. Results show that in general, flux increases with Reynold's number and with lifting parameter. Lower-density walnut shells show a higher flux than silica sands and dust suggesting that on Mars (where {\it g} is lower) the flux would be greater in comparison to Earth. Lower-density walnut shell particles are used to simulate the lower {\it g} of Mars. Future work involves further expansion of the experiment matrix with other materials of varying sizes and densities. Use of the Mars Surface Wind Tunnel facility at NASA Ames Research Center will also allow this study to be simulated at Mars atmospheric pressures.
DE: 5409 Atmospheres--structure and dynamics
DE: 5415 Erosion and weathering
DE: 6225 Mars
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0343 Planetary atmospheres (5405, 5407, 5409, 5704, 5705, 5707)
SC: Planetary Sciences [P]
MN: 2004 AGU Fall Meeting