Remember Me
Or use your Academic/Social account:


Or use your Academic/Social account:


You have just completed your registration at OpenAire.

Before you can login to the site, you will need to activate your account. An e-mail will be sent to you with the proper instructions.


Please note that this site is currently undergoing Beta testing.
Any new content you create is not guaranteed to be present to the final version of the site upon release.

Thank you for your patience,
OpenAire Dev Team.

Close This Message


Verify Password:
Verify E-mail:
*All Fields Are Required.
Please Verify You Are Human:
fbtwitterlinkedinvimeoflicker grey 14rssslideshare1
Languages: English
Types: Unknown
Lobe and cleft patterns are frequently observed at the leading edge of gravity currents, including non-Boussinesq particle-laden currents such as powder snow avalanches. Despite the importance of the instability in driving air entrainment, little is known about its origin or the mechanisms behind its development. In this work we seek to gain a better understanding of these mechanisms from a laboratory scale model of powder snow avalanches using lightweight granular material.\ud \ud The instability mechanisms in these flows appear to be a combination of those found in both homogeneous Boussinesq gravity currents and unsuspended granular flows, with the size of the granular particles playing a central role in determining the wavelength of the lobe and cleft pattern. When scaled by particle diameter a relationship between Froude number and the wavelength of the lobe and cleft pattern is found, where the wavelength increases monotonically with Froude number. This relationship, in addition to Particle Image Velocimetry analysis, provides evidence for the existence of pairs of counter-rotating vortices at the leading edge of these currents, which play a key role in the development of the lobe and cleft pattern.\ud \ud The internal pressure of these flows is found to scale with the dynamics of the large vortex-like structure that is observed within the head of the current.
  • The results below are discovered through our pilot algorithms. Let us know how we are doing!

    • C. Ancey. Powder snow avalanches: Approximation as non-Boussinesq clouds with a Richardson number-dependent entrainment function. Journal of Geophysical Research, 109(F01005), 2004. doi:10.1029/2003JF000052.
    • C. Ancey. Plasticity and geophysical flows: A review. Journal of NonNewtonian Fluid Mechanics, 142(4-35), 2007.
    • M. A. Hampton. The role of sub-aqueous debris flow in generating turbidity currents. Journal of Sedimentary Petrology, 42:775-793, 1972.
    • C. H¨artel, F. Carlsson, and M. Thunblom. Analysis and direct numerical simulation of the flow at a gravity-current head. Part 2. The lobe-and-cleft instability. Journal of Fluid Mechanics, 418:213-229, 2000.
    • F. Hermann, J. Hermann, and K. Hutter. Laboratory experiments on the dynamics of powder snow avalanches. In International Symposium on Avalanche Formation, Movement and Effects, Proceedings of the Davos Symposium, Sept. 1986, volume IAHS-Publ. No. 162, pages 431-439, 1987.
    • R. C. Hibbeler. Engineering Mechanics: Statics and Dynamics. Pearson, Prentice Hall, 11th edition, 2007.
    • E. J. Hopfinger and J. C. Tochon-Danguy. A model study of powder snow avalanches. Journal of Glaciology, 81:343-356, 1977.
    • K. Hutter, S. B. Savage, and Y. Nohguchi. Numerical, analytical, and laboratory experimental studies of granular avalanche flows. Annals of Glaciology, 13:109-116, 1989.
    • A. Jackson, B. Turnbull, and R. Munro. Scaling for lobe and cleft patterns in particle-laden gravity currents. Nonlinear Processes in Geophysics, 20: 121-130, 2013.
    • K. Kawada, K. Nishimura, and N. Maeno. Experimental studies on a powdersnow avalanche. Annals of Glaciology, 13:129-134, 1989.
    • J. J. Keller and Y. P. Chyou. On the hydraulic lock exchange problem. Journal of Applied Mathematics and Physics, 42:874-909, 1991.
    • J. S. Lim. Two-Dimensional Signal and Image Processing, pages 469-476. Prentice Hall, Englewood Cliffs, NJ, 1990.
    • J. E. Simpson. Effects of the lower boundary on the head of a gravity current. Journal of Fluid Mechanics, 53(4):759-768, 1972.
    • J. L. Vinningland, Ø. Johnsen, Flekkøy E. G., R. Toussaint, and K. J. M˚aløy. Size invariance of the granular Rayleigh-Taylor instability. Physical Review E, 81(041308), 2010.
    • C. V¨oltz, W. Pesch, and I. Rehberg. Rayleigh-Taylor instability in a sedimenting suspension. Physical Review E, 65(011404), 2001.
  • No related research data.
  • Discovered through pilot similarity algorithms. Send us your feedback.

Share - Bookmark

Cite this article