The discrete element method (DEM) has become a standard and widely accepted approach for the modeling and simulation of granular and multiphase flows. However, when DEM is applied to large-scale industrial systems, the computational cost generally becomes prohibitively high because of the enormous number of particles that must be tracked. To overcome this limitation, scaling-law-based modeling has attracted considerable attention as an effective strategy to reduce computational expense while retaining essential physical fidelity. The author’s group pioneered the development of a coarse-grained DEM [1] as a scaling-law model within the DEM framework. The fundamental concept of the coarse-grained DEM is straightforward: a group of original particles is represented by a single coarse-grained particle in such a way that the total energy of the system is conserved. Based on this principle, interaction forces and transport processes are appropriately scaled, enabling efficient simulation of large systems. The validity and robustness of the coarse-grained DEM have been demonstrated through extensive validation studies [2-5], including applications to industrial gas–solid and gas–solid–liquid flows. More recently, an advanced heat transfer model [6] has also been incorporated into the coarse-grained DEM, further extending its applicability to thermally coupled processes. Consequently, the coarse-grained DEM now provides a powerful and practical tool for simulating large-scale industrial multiphase systems with significantly reduced computational cost. This study was financially supported by JSPS KAKENHI (No. 24K22289), the Social Cooperation Program for Fundamental Technologies on Powder Process Digital Twin in The University of Tokyo, and the Social Cooperation Program for Digital Twin Fundamental Technology Course for Next Generation Resource Circulation Solutions in The University of Tokyo.