Author(s): Takashi Sasaki; Kuniaki Sato; Akira Wada; Rabindra Raj Giri
Keywords: DNAPL (Dense non-aqueous phase liquid); Random walk process; Numerical method; Pheriatic aquifer; Entrapment effect; TVD (Total variation diminishing) scheme
Abstract: The recent progress of numerical methods on DNAPLs (Dense Non-Aqueous Phase Liquids) migration and their application to field sites have posed some possibilities of measures against groundwater contamination. The study aims at framing of mathematical model for analyzing DNAPL migration on taking both forms in traveling droplets with entrapment detention and solute dispersion. A coupled finite difference method with random walk process (FDM-RWP) is proposed for simulating typical patterns of traveling droplets and DNAPL fingering as well as probable solute concentration using identified entrapment coefficient λ=0. 2~0. 05 (m-1), based on experiments and field data. According to adaptation of FDM-RWP to field data, dispersion lengths αaL, and αaT in a dispersion coefficient Da and initial DNAPL concentration C0 at a polluted source are identified as αaL=100m, αaT=10m and C0 =22. 2mg/ℓ, respectively. The results presented here may suggest that the formulation of entrapped coefficient λ is important to model DNAPL migration in groundwater, and a new mathematical model (FDM- RWP) can realize DNAPL droplets penetration process and its quantification in addition to the deterministic modelization.