| This article has been：Browse 5001Times Download 6489Times |
|
|
|
| DOI： |
|
| Calculating Mass Transfer Between Waters inside and between Aggregates in Aggregated Soils Using Tomography and Pore-scale Modelling |
|
CHEN Xuejun， JIANG Baoliang， ZHANG Xiaocai
|
|
Jiyuan Vocational and Technical College, Jiyuan 454650, China; North China University of Water Resources and Electric Power, Zhenzhou 450016, China
|
| Abstract: |
| Most natural soils are aggregated due to the impact of soil organic matters and soil micro organisms. In aggregated soil, mass transfer between waters inside and between its aggregates is an important process for soil to retain and supply water and nutrients, but is difficult to measure experimentally. Therefore, in chemical transport modelling such mass transfer is often described using an empirical memory function with its parameters obtained by calibrating against experimental data. In practical applications, however, it is impossible to judge that a calibrated memory function correctly describes the processes occurring in soil or it is just a bridge to link model and measurements. Instead of using empirical memory function, we propose in this paper to directly calculate it using soil image and pore-scale modelling. Images of three soils are acquired using x-ray computed tomography at resolution of 30 μm with the between aggregates pores and aggregate geometries explicitly resolved. The mass transfer between solute inside and between the aggregates is calculated using a pore-scale modeling for difference solutes. The results showed that the commonly used exponential memory function associated with the mobile-immobile water model is unable to describe the mass exchange in all three soils. As an improvement, we propose and prove a generalized gamma distribution to describe the mass exchange processes. |
| Key words: mass transfer; X-ray micro-tomography; aggregated soils; pore-scale modelling; mobile-immobile water model |
|
|
