Dynamics of Agitated Wet Granular Matter

• Applicant: Privatdozent Dr. Kai Huang
• Subject Area: Statistical Physics, Nonlinear Dynamics, Complex Systems, Soft and Fluid Matter, Biological Physics
• Term: from 2012 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 214347455

• Final Report Year: 2016

Final Report Abstract

Understanding the dynamics of wet granular matter (e.g. wet sand on the beach) from a physical perspective is a topic of building fundamentals for a wide range of applications with substantial impact on our society: From the prediction of natural disasters (e.g. landslide, debris flow) to the enhancement of energy efficiency in industries (e.g. granulation process). At the ‘microscopic’ scale, our investigation on a single particle bouncing on a liquid coated surface suggested a convenient way of predicting the normal coefficient of restitution for wet particles. Due to the widespread applications, this finding will be beneficial for both physicists and engineers using particle-based simulations to predict the collective behavior of wet granular matter. At the ‘macroscopic’ scale, our investigations on the critical behavior (e.g. phase transitions and pattern formation) in agitated wet granular matter – a nonequilibrium model system – revealed that the existing knowledge for systems in thermodynamic equilibrium can be extended to understand granular dynamics, provided that the particles are effectively mobilized. The ‘macroscopic’ and ‘microscopic’ worlds are closely connected with each other in the sense that the critical behavior of agitated granular systems can often be traced down to the balance between the energy injection and dissipation at a particle level. The biggest surprise is the 1/f noise discovered in the vicinity of the melting transition of an agitated wet granular monolayer. As fluctuations are a common feature for all nonequilibrium systems, this discovery suggests an alternative way of characterizing critical behavior in nonequilibrium systems. This can be of general interest. In terms of public relation, it is worth mentioning that our work is covered in a Spectrum article ‘Digitalisierung in der Messtechnik’ dedicated to a nonscientific community. Huang, K. & Rehberg, I. 2015 Digitalisierung in der Messtechnik. Spektrum (Universität Bayreuth), Ausgabe 2

Publications

• 2013 Analogue of surface melting in a macroscopic nonequilibrium system. Phys. Rev. E 88, 062201
  May, Christopher; Wild, Michael; Rehberg, Ingo & Huang, Kai
  
• 2013 Dynamics of rotating spirals in agitated wet granular matter. in AIP Conf. Proc. 1542, 702–705
  Huang, K., Butzhammer, L. & Rehberg, I.
  
• 2013 Scaling of the normal coefficient of restitution for wet impacts. in AIP Conf. Proc. 1542, 787–790
  Müller, T., Gollwitzer, F., Krülle, C. A., Rehberg, I. & Huang, K.
  
• 2015 Ordering in granular-rod monolayers driven far from thermodynamic equilibrium. Phys. Rev. E 91, 062207
  Müller, Thomas; de las Heras, Daniel; Rehberg, Ingo & Huang, Kai
  
• 2015 Pattern formation in wet granular matter under vertical vibrations. Phys. Rev. E 92, 012202
  Butzhammer, Lorenz; Völkel, Simeon; Rehberg, Ingo & Huang, Kai
  
• 2015 Role of defects in the onset of wall-induced granular convection. Phys. Rev. E 91, 32206
  Fortini, Andrea & Huang, Kai
  
• 2015. 1/ f noise on the brink of wet granular melting. New J. Phys. 17, 83055
  Huang, Kai
  
• 2016 Influence of the liquid film thickness on the coefficient of restitution for wet particles. Phys. Rev. E 93, 42904
  Müller, Thomas & Huang, Kai