Rafi Blumenfeld ...

... and theoretical physics: a never-ending story

Rafi 2014



Some aspects of the physics of granular matter offer insight into the much discussed nature of time !

September: First paper on active matter submitted: "Vertical dynamics of a horizontally-oscillating active object in a 2D granular medium"

September: Organising an international Symposium (with Mike Cates and Mark Warner) Soft Matter - Theoretical and Industrial Challenges, Celebrating the Pioneering Work of Sir Sam Edwards, (September 7 - 9) Cambridge, UK

August: Invited talk at the 3rd International conference on:
Packing: across length scales, (August 29 - September 1) Shanghai, China

August: Organising an International Workshop:
Soft and granular matter in ambient and extreme conditions 2016 (SGMAEC2016), (August 22 - 25) Changsha, Hunan, China

July: Talks in Tsukuba University, Tsukuba and the Yukawa Inst., Kyoto, Japan

April: Our recent highlighted paper in Phys. Rev. Lett. is making a bit of news

March: Invited talk at the American Physical Society (APS) meeting, (March 14 - 18) Baltimore, MD, USA: "Granular statistical mechanics - Building on the legacy of Sir Sam Edwards" (Abstract)

January: Invited talk at the conference Dynamic Days, (January 7 - 10) Durham, NC, USA: "Granular statistical mechanics - Status report and future directions"

Archived news


These pages have grown uncontrollably from a modest beginning in 1993, when a home page was a rarity. I cannot pinpoint when exactly over the years was it that I lost the fight against this unstable self-(dis)organised growth. I was probably never in control.

You may notice that the pages are written in the old basic HTML format. This is because none of the current fancy new softwares, which essentially do all the nitty-gritty work, existed. Hence, there are no fancy java scripts, flashing lights and colours, background music, or automatically starting videos. This may be one of the last bastion of the HTML purists, uncluttered by sights or sounds. As my friend Peter once put it: "This is about delegation of responsibility. About trust. About subsidiarity. It's a small-scale mirror of so many of our every day problems."

Anyway, my publication list is updated regularly ... after a fashion. The rest not so much. If your time is short, I recommend to browse my 'Selected publications' and then move to the less frequently updated 'research interests' page. Much of the latter is distilled into limericks at the bottom of this page. You are, of course, welcome to visit all the pages but be warned that there is always the possibility of getting lost in the overgrown meandering paths.

Often, when I finish developing a model or a theory, I write a limerick that summarises it. The weight and rythm is not always great, but they do describe, as accurately as possible in 5 lines, the modelling of the relevant physics. Below are the limericks I wrote so far, each with a link to a paper that the work produced, if it has.

On Force Chains paper
Rafi 10/2009
Force chains can be found
And in granular materials they abound
Now although isostaticity
Has caused great turbidity
That particular stress theory is sound

(RB April 2006)

On Stato-elasticity I (paper in preparation)
Rafi 10/2009
Some put their faith in Elasticity
Others swear on Isostaticity
But I stand before you
To tell you boldly
That Stato-elasticity is the one and only

(RB April 2008)

On Stato-elasticity II (paper in preparation)
Rafi 10/2009
A theory called Elasticity
Was challenged by Isostaticity
But I tell you boldly
That real packs mostly
Should follow Stato-elasticity

(RB April 2008)

On Couette flow of da Vinci fluids paper 1, paper 2
Rafi 10/2009
O' whirling sands in the cylinder flow
Layer by streamline they clump and they slow
Grains rub their neighbour
Dissipating much labour
And da Vinci fluids explain it, gung-ho!

(RB November 2010)

Polymer chain pullout with AFM paper 1, paper 2
Rafi 10/2009
Pick a polymer chain with the tip
Bond it tight, don't let it slip
It pulls out in a stutter
Here a jump, there a flutter
Thus, through the tube it would not zip

(RB April 2006)

Fractures propagating in disordered materials paper 1, paper 2
Fractures evolving in disordered matter
Spawn voids that expand, grow large and scatter
Swallowed by the crack
With a supersonic smack
They get to become part of the big antimatter

(RB September 2014)

On modeling Disordered Auxetics paper 1, paper 2
Rafi 10/2009
On pulling they swell, on pushing they dense
Auxetic materials defy common sense
They expand and dilate
Causing heated debate
But iso-auxeticity dispels the suspense

(RB June 2015)

On contact granular statistical mechanics I (paper in preparation)
One moment they're there and then they are gone
Inter-grain contacts do not linger on
Their dynamics mysterious
And their modelling spurious
But contact potential explains it, c'est bon!

(RB December 2015)

On contact granular statistical mechanics II (paper in preparation)
Shear them to slide and knock them to clap
Inter-grain contacts are an energy trap
Their dynamics obscure
To the theorist's pure
But contacture statistics fills out the gap

(RB December 2015)

On Sam Edwards
Rafi 10/2009
He pushed science to places unmanned
Made physics of squishies and sand
Fokker-Planck here
Replica there
And all with some wit and Chablis glass in hand

(RB April 2016)

On Force Chains Curving Back (paper in preparation)
Rafi 10/2009 Rafi 10/2009
Back-curving stress chains in cylinders loop
Detected and measured in Behringer’s group
They leak to the cone
They branch on and on
And isostaticty explains all this soup

(Experimental figure courtesy of Jie Zhang)
(RB April 2016)