Discussion of “The asymmetry of stress in granular media”: [J.P. Bardet and I. Vardoulakis,Int. J. Solids Struct. 2001, Vol. 38, No. 2, pp. 353–367]

The discussion concerns a recently proposed definition of average stress for granular materials, one which can manifest asymmetry in the absence of surface couples, body couples, and contact couples. The average stress was derived from a new postulate that employs virtual work terminology. The discussion shows that the postulate leads to a non-unique average stress and to a non-unique stress asymmetry.     

Handbook of Fluidization,Mooson Kwauk,Hongzhong Li （Eds.）.

Fluidization is an important process technology and is ubiquitously present in the process industry. The phenomena of fluidization also represent one of the most fascinating fluid-particle interactive behaviors in nature that are manifested by complex, intertwining science and engineering principles. Even though it is a centuries old practice, pursuit of the fundamental understanding of fluidization has its origins in the 1940s. Since the 1960s, fluidization has been a vibrant field for fluid mechanics, particle mechanics, as well as modeling and computation. From the historical perspective, Professor Mooson Kwauk and Professor Richard Wilhelm＇s 1948 article ＂Fluidization of Solid Particles,＂ is proved to be a pioneering work that sets a stage for subsequent fundamental studies in the characteristics of fluidization. As the field has evolved over the last six decades, Professor Kwauk has been a leader of fluidization research in China and the world,