Complex systems exist in every aspect in nature and society, ranging from elemental particle dynamics to cosmological celestial body interactions. Computational modeling is a powerful tool to elevate our understanding of the mechanisms in complex systems. Discrete particle methods which directly simulate complex systems by real or artificial particles, such as the Direct Simulation Monte Carlo method for rarified gas flows, account for a large portion in the modeling of complex systems. The advantages of discrete particle methods over traditional continuum methods are, for example, mathematical concision, easy implementation, and high parallelization. This special issue aims to foster the development and application of discrete particle approaches in modeling of complex systems. Papers submitted to this special issue are expected to advance the state of the art of discrete simulation of complex systems.

We invite authors to submit original research and review papers on the fundamentals, development, and application of discrete particle approaches in simulation of complex systems. We are particularly interested in articles that propose or use novel discrete particle methods to unravel the mechanisms of complex systems for better understanding.

Potential topics include, but are not limited to:

• Mathematical development, verification, and improvement of discrete particle methods for simulation of complex systems at all scales, for example, molecular dynamics (MD), lattice Boltzmann method (LBM), and smoothed particle hydrodynamics (SPH)
• Computer realization and algorithm optimization of discrete particle methods for effective modeling of complex systems
• Practical application of discrete particle methods to the simulation/description of complex systems
• Combination of discrete particle and continuum methods for simulation of complex systems
• Large-scale discrete simulation of complex systems using advanced high performance computing technologies, such as MPI, OpenMP, and GPU
• Development of advanced numerical skills for high-resolution or large-scale simulation of complex systems, such as adaptive particle split-coalescence refinement
• Multiscale discrete simulation of complex systems for scale coupling/bridging using hybrid discrete particle methods, such as the coupling between MD and SPH for interface capture