低炭素社会構築のためのCCS

[1K0701-09-07] Modeling solute transport in randomly packed porous media influence of particle geometry, pore size distribution and local heterogeneity

○Chunwei Zhang¹, Tetsuya Suekane¹ (1. Tokyo Institute of Technology)

Keywords:Dispersion, Particle geometry, Pore size distribution, Porous media heterogeneity, LBM

Transport of nonreactive passive tracers through complex micro structured porous media has great implications in multiple natural and engineering applications, such like contaminants remediation and hydrogeologic resources recoveries. Dispersion process can be viewed as the competitional interplay between molecular diffusion and advection flow along the tortuous flow path. Even though different dispersion regimes as a function of Pe number were recognized both experimentally and analytically, the impact of particle geometry, pore size distribution and local heterogeneity has not been well understood. Therefore, in this paper, we simulate dispersion of the point injected dilute tracer plumes in the glass beads, melamine resin particles and Berea sand stone respectively. The porous Medias are three dimensionally reconstructed from the high resolution Micro CT images. The glass beads and melamine resin particles are adjusted the same porosity but different particle size distribution, while the Berea sand exhibits smaller porosity and lower permeability resembling more heterogeneous flow. Then, we employ the LBM method to simulate both the fluid flow and tracer transport behavior in the designated porous media, whereby the asymptotic dispersion in both longitude and transverse direction are estimated. As expected, wider distributions of the pore size as well as increasing heterogeneity will enhance the dispersion coefficient. However, the transient time for dispersion to stabilize will elongate as the tracer particles have to sample enough velocity fluctuations before getting the scholastically convergent dispersion coefficient. The particle geometry has a more profound influence on fluid flow and hence dispersion behavior. The curvature of multiple simple geometries will be analyzed through simulations, giving hints to dispersion enhancement through geometry optimization.