Dr. Gary W. Delaney

Work with collaborators from University of Erlangen-Nuremberg, Max Planck Institute and the Australian National University on the structure of 3D frictional ellipsoid packings is featured on the cover of the current issue of Physical Review Letters. Details of this work is given in our paper Local Origin of Global Contact Numbers in Frictional Ellipsoid Packings .

Scientists have long considered packing models in which non-overlapping grains of smaller and smaller sizes are placed according to a specified set of rules. These date back to the work of Apollonius of Perga ca. 200B.C. We have performed extensive numerical simulations using up to 10

I have written a software package that employs a Monte-Carlo type packing algorithm to generate dense jammed random packings of 2D grains of arbitrary shape. We have used this to investigate the packing properties of elliptical grains, with a very interesting variation in the packing density of the grains observed as the ellipticity is varied. A video of the generation of a packing of ellipses with an aspect ratio of 0.7 can be downloaded here (

In textbook descriptions of Newton's cradle, it is generally claimed that displacing one ball will result in a collision that leads to another ball being ejected from the line, with all others remaining motionless. It has however been shown that a realistic description is more subtle. We have performed simulations of Newton's cradle that reproduce the initial break-up of the line of balls at the first collision, the eventual movement of all the balls in phase, and is in good agreement with our experimentally obtained data. The first effect is due to the finite elastic response of the balls, and the second is a result of viscoelastic dissipation in the impacts. We have also analyzed a dissipation-free ideal Newton's cradle which displays complex dynamics. A video of our simulation can be downloaded here (

2. "Onset of rigidity in 3D stretched string networks", G. W. Delaney and D. Khoury European Physical Journal B, 86, 44, 2013.

3. "Comparison of permeability of model porous media between SPH and LB", P.M. Dupuy, P. Austin, G.W. Delaney and M.P. Schwarz, Computer Physics Communications, 182, 2249-2258, 2012.

4. "Defining Random Loose Packing for Nonspherical Grains", G.W. Delaney, J.E. Hilton and P.W. Cleary, Physical Review E, 83, 051305, 2011.

5. "The packing properties of superellipsoids", G.W. Delaney and P.W. Cleary, Europhysics Letters , 89, 34002, 2010.

6. "Combining tomographic imaging and DEM simulations to investigate the structure of experimental sphere packings", G.W. Delaney, T. Di Matteo and Tomaso Aste, Soft Matter, 6, 2992-3006, 2010.

7. "Disordered spherical bead packs are anisotropic", G. E. Schroeder-Turk, W. Mickel, M. Schroeter, G. W. Delaney, M. Saadatfar, T. J. Senden, K. Mecke and T. Aste, Europhysics Letters , 90, 34001, 2010.

8. "Relation Between Grain Shape and Fractal Properties in Random Apollonian Packing with Grain Rotation", G.W. Delaney, S. Hutzler and T. Aste, Physical Review Letters, 101, 120602, 2008.

9. "Crystalline arrangements of microbubbles in monodisperse foams", A. van der Net, G.W. Delaney, W. Drenckhan, D. Weaire and S. Hutzler,

10. "Onset of rigidity for stretched string networks", G.W. Delaney, D. Weaire and S. Hutzler,

11. "Rheology of ordered foams on the way to Discrete Microfluidics", W. Drenckhan, S.J. Cox, G. Delaney, H. Holste, D. Weaire and N. Kern,

12. "Random packing of elliptical disks", G. Delaney, D. Weaire, S. Hutzler and S. Murphy,

13. " Rocking Newton's Cradle ", S. Hutzler, G. Delaney, D. Weaire and F. MacLeod,

Email: gdelaney "AT" gmail "DOT" com