Mini-workshop on "Jamming, rheology and granular matter"

Contribution List

1. Impact-induced hardening in dense suspensions

Hisao Hayakawa (Yukawa Institute for Theoretical Physics)

7/9/25, 9:30 AM

In this talk, I present a summary of studies on the impact of a projectile in dense suspensions, based on published papers that theoretically and experimentally [1-4].
In the first part, I focus on the early-stage dynamics of the impact, which the floating model can describe without consideration of the elastic force acting on a projectile [2,4].
In the second part, I discuss how the...

10. Mixing evaluation in CG-DEM simulations of rotating drum regimes

Balazs Fuvesi

7/9/25, 10:00 AM

The discrete element method (DEM) is commonly used to simulate granular flows and optimise processes involving particulate materials in various industries. DEM treats granular materials as individual particles, however the large number of particles present in industrial scales leads to high computational demands, making it less feasible for industrial scale simulations. Coarse graining (CG)...

2. Mean-field theory of vibrational density of states of jammed packing

Harukuni Ikeda (Yukawa Institute for Theoretical Physics)

7/9/25, 10:30 AM

Several mean-field theories predict that the Hessian matrix of amorphous solids converges to the Wishart matrix in the limit of large spatial dimensions. Motivated by these results, we calculate here the density of states of random packing of harmonic spheres by mapping the Hessian of the original system to the Wishart matrix. We compare our result with that of previous numerical simulations...

3. Weakly Nonlinear Analysis Based on Unstable Modes in Amorphous Solids

Kota Noto (Yukawa Institute for Theoretical Physics)

7/9/25, 11:00 AM

We performed a weakly nonlinear analysis of particle configurations that exhibit negative eigenvalues in the Hessian matrix. By expanding the potential energy in terms of particle displacements, we found that the linear term enhances the instability, whereas the cubic term suppresses its growth. A comparison between the derived nonlinear equation and numerical simulations revealed qualitative...

7. Kinetic theory of moderately dense dry granular particles under a simple shear

Satoshi Takada (Tokyo University of Agriculture and Technology)

7/9/25, 11:30 AM

We formulate the kinetic theory of dry granular particles under a simple shear based on the Enskog and Grad approximations. We get a complete set of equations for the kinetic stress and the collisional contribution to the stress within this approximation. The steady solution under this approximation reproduces the quantitatively accurate results for the shear viscosity and kinetic temperature...

5. Hysteresis and Marginal Stability of Jammed Cohesive Grains

Michio Otsuki (Shimane University)

7/9/25, 1:30 PM

We numerically investigate the shear modulus of jammed amorphous solids composed of cohesive grains. While repulsive grains exhibit critical scaling of the shear modulus as a function of the pressure or the excess coordination number, cohesive grains show pronounced hysteresis, which obscures the scaling behavior observed in repulsive systems. We relate this deviation to a possible breakdown...

6. Anomalous Enhancement of Structural Stability due to Static Friction

Ryudo Suzuki (Kyoto University)

7/9/25, 2:00 PM

Many structures around us achieve mechanical stability against their
own weight through friction. Examples include arch bridges,
house-of-cards construction, and sandpile stabilized by their angle
of repose. In these systems, friction and geometry work together
to suppress sliding and enables mechanical equilibrium. But what
(if any) mechanism contributes to the strength of...

11. A Data-Driven Framework for Efficient Hierarchical Multiscale Modeling of Thermomechanical Effects in Granular Materials

Rafael Rangel (Twente)

7/9/25, 2:30 PM

Granular materials are prevalent in both natural and industrial contexts, presenting complex physical behavior that arises from their discrete composition. This complexity is further amplified by thermal effects, which explain the current gaps in achieving a comprehensive understanding of the thermomechanics of granular matter. This talk will present a data-driven framework to efficiently...

8. From flowing to static: statistics of elasto-plastic transitions

Stefan Luding (Twente)

7/9/25, 3:15 PM

How do soft granular materials (or dense amorphous systems) respond to
externally applied deformations at different rates – from fast to slow
to very slow – and for different system sizes? This long-standing
question was intensively studied for shear deformation modes, but only
more recently also for isotropic deformations, like
compression-decompression cycles [1,2]. For moderate strain...

9. Unified Understanding of Nonlinear Rheology near the Jamming Transition Point

Takeshi Kawasaki (Osaka University)

7/9/25, 5:00 PM

When slowly sheared, jammed packings respond elastically before yielding. This linear elastic regime becomes progressively narrower as the jamming transition point is approached, and rich nonlinear rheologies such as shear softening and hardening emerge. However, the physical mechanism of these nonlinear rheologies remains elusive. To clarify this, we numerically study jammed packings of...

4. Jamming of deformable foams

Kuniyasu Saitoh (Kyoto Sangyo University)

7/9/25, 5:30 PM

The jamming transition of soft athermal particles has long been explored by numerical models of undeformable spheres/circles and the researchers have extensively studied the critical behavior of the particles near jamming. It is now well known that the shear modulus of undeformable particles scales as the square root of the proximity to the jamming transition density. However, the square-root...