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Umberto Marini Bettolo Marconi Professor of Physics, Dipartimento di Fisica Universita di Camerino Address: Dipartimento di Fisica, Via Madonna delle Carceri, 62032, Camerino (Mc), Italy phone +39+0737-402538 e-mail umberto.marini.bettolo@roma1.infn.it or umberto.marinibettolo@unicam.it

  • 1979 - 1980 Fellowship Royal Society-Accademia dei Lincei. Department of Theoretical Chemistry, Oxford University, Oxford, UK.

  • 1981 Fellowship Della Riccia.

  • 1981 - 1983 Post-Doc, Department of Physics, Freie University, Berlin, Germany.

  • January-June 1983 Visiting scientist, H.H. Wills Physics Laboratory University of Bristol, UK.

  • 1984-1986, Post-Doc, H.H. Wills Physics Laboratory University of Bristol, UK.

  • January-June 1987 Postdoc, University of Rio Pedras, Departamento de Fisica, (Portorico, USA).

  • June-December 1987, Visiting Scientist, Dept. of Chemical Engineering, Cornell University, (Ithaca, NY, USA).

  • 1988 Professore a contratto University of Tor Vergata, Roma. September 1988-March 1990 Ricercatore, Istituto Nazionale di Fisica Nucleare (Articolo 36), APE Group, INFN, Rome.

  • April 1990-2000 Ricercatore Universitario Confermato, Condensed matter, University of Camerino, Italy.

  • February 2001-present Professore Associato Confermato di Struttura della materia, University of Camerino, Italy.

Research Interests

  • Granular Media
  • Phase transitions and Critical Phenomena.
  • Capillary Condensation and Porous media.
  • Complex fluids and Colloidal Systems.
  • Density functional methods for classical fluids with application to dynamic properties.

Publications

Organization of Conferences

I have co-organized 3 Meetings on Statistical Mechanics at Camerino and a Workshop on Granular System in Pisa in 1998. I also coorganized the Conferenza Nazionale di Meccanica Statistica di Parma Italy from 1993 to 1997.

Member of the Scientific Committee of the INFM Conference held in Fai della Paganella and now in Levico Terme.

* RESEARCH*

Research

The last few years have seen an extraordinary growth of interest in complex systems. From physics to biology, from economics to cognitive sciences, a new vocabulary is emerging to describe discoveries about wide-ranging and fundamental phenomena.

Statistical Mechanics has become in the last decades the standard tool to study problems once considered to be out of the reach and the scopes of Physics. It has been in fact applied to the study of the complex behavior of various kinds of systems of areas such as biological and sociological sciences, finance, economy, theory of decisions, networks. In particular several disciplines connected with Engineering are now attracting more and more the interest of physicsts. Granular matter is a remarkable example of these new disciplines. The problem of understanding granular materials is widely recognized as one of the main problems of engineering and industry. A brief list of typical "granular" products comprehends: grains, powders, sands, pills, seeds and similar particulate materials. More generally, granular materials are a very large set of substances used in the industry and in the everyday life: ceramics, fertilizers, cosmetics, food products, paper, conductor pastes, resins, electronics, polymers, suspensions, solid chemicals, construction materials and so on. The international economic impact of particle processing is substantial. The value added by manufacture that involves particulate has been estimated to be a minimum of 80/100 billion/year, which is of the order of the US trade deficit with Japan. The US Dept. of Commerce has estimated the total economic impact of particulate products to be one trillion/year. Despite economic impact, however, insufficient attention is paid to difficulties associated with the processing of particles. An improved understanding of micromechanics of granular media requires an interdisciplinary approach involving both physicists and engineers.

Mechanical engineers and geologists have studied Granular Matter for at least two centuries and found several empirical laws describing its behavior. Physicists have joined in more recently and are interested in formulating general laws. For them granular matter is a new type of condensed matter, showing two states: one fluid-like, one solid-like. But there is not yet consensus on the description of these two states. According to P.G. de Gennes Granular matter now is at the level of solid-state physics in 1930.

Granular matter also represents an important paradigm for the study of non-equilibrium stationary states. Due to the dissipative nature of the interactions granular gases have to be considered as open systems and therefore concepts from equilibrium thermodynamics cannot be applied, at least in straightforward way. The project we propose focuses on granular fluids. We intend by granular fluid a large number of particles, whose size is larger than a micron, colliding with one another and losing a little energy in each collision. Below one micron thermal agitation is important and Brownian motion can be observed. Above one micron, thermal agitation is negligible. However,if such a system is shaken to keep it in motion, its dynamics resembles that of fluids, in that the grains move randomly.

One of the key differences between a granular material and a regular fluid is that the grains of the former lose energy with each collision, while the molecules of the latter do not. Even when the inelasticity of the collisions is small, it can give rise to dramatic effects, including the Maxwell Demon effect and the phenomenon of granular clustering. Experiments and molecular dynamics simulations alike show that granular gases in the absence of gravity do not become homogeneous with time, but instead form dense clusters of stationary particles surrounded by a lower density region of more energetic particles. From a particulate point of view, one can explain these clusters by noting that when a particle enters a region of slightly higher density, it has more collisions, loses more energy, and so is less able to leave that region, thus increasing the local density and making it more likely for the next particle to be captured.

-- UmbertoBettolo? - 05 Mar 2007

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