Isothermal diffusion of water vapor in unsaturated soils based on Fick’s second law

In arid regions, water vapor diffusion predominates the total water migration in unsaturated soil, which significantly influences agriculture and engineering applications. With the aim of revealing the diffusion mechanism of water vapor in unsaturated soil, a water vapor migration test device was de...

Full description

Saved in:
Bibliographic Details
Published in:Journal of Central South University 2020-07, Vol.27 (7), p.2017-2031
Main Authors: Liu, Fei-fei, Mao, Xue-song, Zhang, Jian-xun, Wu, Qian, Li, Ying-ying, Xu, Cheng
Format: Article
Language:English
Subjects:
Agricultural engineering
Arid regions
Diffusion
Diffusion coefficient
Engineering
Mathematical analysis
Mathematical models
Matrix methods
Metallic Materials
Moisture content
Soil conditions
Soil moisture
Soil suction
Soil water
Soils
Unsaturated soils
Water vapor
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:In arid regions, water vapor diffusion predominates the total water migration in unsaturated soil, which significantly influences agriculture and engineering applications. With the aim of revealing the diffusion mechanism of water vapor in unsaturated soil, a water vapor migration test device was developed to conduct the water vapor migration indoor test. The test results demonstrate that the characteristics of water vapor diffusion in unsaturated soil conformed to Fick’s second law. A mathematical model for water vapor diffusion under isothermal conditions in unsaturated soil was established based on Fick’s law. Factors including the initial moisture content gradient, initial moisture content distribution, soil type and temperature that affect the water vapor diffusion coefficient were analyzed. The results show that there was good agreement between the moisture content calculated by the mathematical model and obtained by the indoor experiment. The vapor diffusion coefficient increased with increasing initial moisture content gradient and temperature. When the initial moisture content gradient is constant, the vapor diffusion coefficient increases with the increase of matrix suction ratio in dry and wet soil section. The effect of soil type on the water vapor diffusion coefficient was complex, as both the moisture content and soil particle sizes affected the water vapor diffusion.
ISSN:2095-2899
2227-5223
DOI:10.1007/s11771-020-4427-6