The granular particles often segregate when sizes are dispersed, or the shape is non-spherical. We have studied its structure and rheology recently, and exciting publications will come soon.
Typically, the diffusivity of the center of mass of a particle decreases as the matrix density increases. However, rod diffusivity can exhibit the opposite behavior in certain matrices. This phenomenon has been explained using various fuzzy concepts such as dynamic correlations, geometrical constraints, confinements, or dynamic arrests. We have found that the increase in the diffusion coefficient can even occur in simple Markovian process and have explained the increases in rod diffusivity based on the Markovian nature.
Recently, a type of diffusion called "Brownian yet non-Gaussian diffusion" has been observed. This phenomenon can be explained by the concept of "fluctuating diffusivity," where the diffusion coefficient of a particle varies over time. There are two known origins for fluctuating diffusivity: heterogeneous spatial/temporal environments and conformational fluctuations. However, we have proposed a third novel origin for fluctuating diffusivity in the study of simple binary gas mixtures, which we have studied numerically.
I studied the dynamics of a single tracer particle in an ideal gas and found that it exhibits various interesting behaviors, even in its simple nature. For example, the mean square displacement of the tracer particle has a plateau, and strong non-Gaussian diffusion occurs in certain parameter regimes.