ADEQUACY OF SURFACE DIFFUSION MODELS TO SIMULATE NONEQUILIBRIUM MASS TRANSFER IN SOILS

作者：Hasan Nazmul; Hossain Md Akram^*

来源：Journal of Porous Media, 2012, 15(8): 735-744.

DOI：10.1615/JPorMedia.v15.i8.30

• advective-dispersive transport
• intra-particle diffusion
• nonequilibrium
• mass transfer
• soils

Diffusion from intra-particle pore spaces is considered to be the main reason for the slow release of contaminants from soil. Diffusion-controlled mass transfer can be simulated by the homogeneous surface diffusion model (HSDM). The objective of this paper is to present a simplified HSDM model (SHSDM) and a finite element HSDM model (FEHSDM) to simulate advective-dispersive transport through soils, coupled with intra-particle diffusion, under nonequilibrium conditions and compare these models with the dispersed flow, film and particle diffusion model (DF-FPDM) that has recently been reported in literature. The FEHSDM predictions compare well with experimental data for slightly hydrophobic compounds. The SHSDM and the DF-FPDM predictions, on the other hand, compare well with experimental results for relatively hydrophobic compounds. The SHSDM and the DF-FPDM predictions are practically the same for mass transfer Biot numbers Bi %26gt;= 20. However, considerable difference in the predictions of these two models is observed for Bi %26lt;= 1. The SHSDM and the DF-FPDM, by and large, provide convergent results and remain stable for Peclet numbers Pe %26lt;= 2.5 and Courant number Cr %26lt;= 1.0, with the FEHSDM requiring finer spatial and temporal discretizations.

• 出版日期2012