Nanoparticle-laden flows in porous media constitute a challenging class of multiphase systems in which particle transport is coupled to hydrodynamics and interparticle forces. In such systems, nanoparticle aggregation plays a central role in controlling dispersion and particle retention [1]. We present a pore-scale numerical framework for modeling the transport and aggregation of nanoparticles flowing through randomly packed sphere assemblies. The computations are first validated for cerium dioxide nanoparticles suspended in a potassium chloride electrolyte. The fluid phase is resolved using the lattice Boltzmann method, while the particles are treated using a Lagrangian particle tracking approach based on force balance (LPT/FB) with adaptive time stepping [2,3]. Particle dynamics include hydrodynamic drag, Brownian motion, gravity, buoyancy, van der Waals forces, and electrostatic interactions, allowing for detailed resolution of particle–particle coupling. Aggregation is identified through distance-based criteria linked to the primary minimum of the interaction potential, enabling the evolution of aggregate size distributions to be tracked in space and time. Simulations are conducted to quantify the effects of flow velocity, particle size, and particle concentration on aggregation kinetics. In the diffusion-limited regime, the aggregation rate is found to scale linearly with time and follows a power-law dependence on Reynolds and Schmidt numbers as well as particle concentration. The results provide new insights into granular multiphase dynamics at the microscale in porous environments. REFERENCES [1] V.T. Nguyen, N.H. Pham, D.V. Papavassiliou, Aggregation of Nanoparticles and Morphology of Aggregates in Porous Media with Computations. J. Colloid Interface Sci. 650, 381–395, 2023 [2] V.T. Nguyen, N.H. Pham, D.V. Papavassiliou, Relationship between pore fluid velocity and pore size distribution,” AIChE J., 69(3), Art e17987, 2023 [3] V.T. Nguyen, N.H. Pham, D.V. Papavassiliou, Prediction of the Aggregation Rate of Nanoparticles in Porous Media in the Diffusion-Controlled Regime. Sci. Rep., 14 (1), 1–14, 2024