Monday, May 15, 2023

12:30-14:30, Physics Building, Room 512

Dr. habil. Kai Huang

Associate Professor of Physics

Chair, Division of Natural and Applied Sciences

Duke Kunshan University

ABSTRACT

    From sand dunes to Faraday crispations, granular materials (i.e., large agglomerations of macroscopic particles) are ubiquitous in nature, industry and our daily lives with widespread applications from the prediction of natural disasters (e.g. snow avalanches and debris flows) through the enhancement of energy efficiency in industries (e.g. mining, civil engineering) to emerging new technologies (e.g. powder based additive manufacturing, or 3D printing). Due to the energy dissipation at the individual particle level, granular systems are highly dissipative and consequently their stationary states are typically far from thermodynamic equilibrium. Therefore, understanding how the interactions between individual particles influence the collective behavior is crucial in describing granular materials as a continuum.

    In this talk, ongoing efforts in deciphering the dynamics of granular materials will be presented. From single particle bouncing to collective motion, the following questions will be addressed. At the `microscopic' level of individual particles: How to estimate the energy dissipation associated with the impact of wet particles and consequently predict the coefficient of restitution [1,2]? Stepping further to 'macroscopic' scale, pattern formation scenario in vibrofluidize wet granular layer will be presented and the link to 'microscopic' particle-particle interactions will be elucidated [3-5]. If time allows, I will briefly introduce a self-developed radar tracking setup to 'see through' granular materials for the investigation of granular drag as well as how a better understanding of granular dynamics helps recent applications in space explorations [6-8]. 

REFERENCES

[1] F. Gollwitzer, I. Rehberg, C. A. Kruelle and K. Huang "Coefficient of restitution for wet particles", Phys. Rev. E, 86, 011303 (2012).

[2] T. Mueller and K. Huang "Influence of the liquid film thickness on the coefficient of restitution for wet particles", Phys. Rev. E, 93, 042904 (2016).

[3] Kai Huang and Ingo Rehberg, "Period tripling causes rotating spirals in agitated wet granular layers", Phys. Rev. Lett. 107, 028001 (2011)

[4] Lorenz Butzhammer, Simeon Voelkel, Ingo Rehberg and Kai Huang, "Pattern formation in wet granular matter under vertical vibrations",  Phys.Rev. E 92, 012202 (2015)

[5] Andreas Zippelius and Kai Huang, "Density-wave fronts on the brink of wet granular condensation",  Sci. Rep. 7, 3613 (2017)

[6] Felix Ott, Stephan Herminghaus, and Kai Huang "Radar for tracer particles", Rev. Sci. Instrum 88, 051801 (2017).

[7] Kai Huang, Dariel Hernandez Delfin, Felix Rech, Valentin Dichtl, and Raul C Hidalgo, "The role of initial speed in projectile impacts into light granular media" Scientic Reports 10, 3207 (2020).

[8] Yajie Feng, Shuo Huang, Yong Pang, Kai Huang*, and Caishan Liu*, Journal of Fluid Mechanics, 935, A26 (2022)