Analysis of Non-Equilibrium Phase Change in Transfers at Low Water Content by Considering the Film Flow

American Journal of Environmental Sciences

article

Marcel Bawindsom Kébré¹  François Ouédraogo²  Bétaboalé Naon²  Fabien Cherblanc³  François Zougmoré¹ 

[1]Université Joseph KI-ZERBO

[2]Université Nazi BONI

[3]Université de Montpellier

关键词: Sandy Soil;    Low Water Content;    Phase Change;    Non-Equilibrium;    Film Flow;    Hydraulic Conductivity;   

DOI  :  10.3844/ajessp.2021.1.13

学科分类：环境科学（综合）

来源: Science Publications

【 摘 要 】

In this study, we analyze the effect of non-equilibrium phase change on transfer at low water content in a sandy soil by considering the contribution of film flow in the motion of liquid water. Indeed, most of the non-equilibrium study methods use for hydraulic conductivity, the van Genuchten-Mualem (VGM) capillary model which does not consider the film flow occurred at low water contents. Thus, we conduct a theoretical study by using an unidirectional non-equilibrium two phase flow model to simulate water transfers by filtration of liquid water and diffusion of water vapour coupled by liquid/gas phase change. We then compare the results of the non-equilibrium with the classical model of VGM for hydraulic conductivity function and another model considering the film flows. The numerical simulation is based on a column of sandy soil exposed to a controlled atmosphere. We observe that the shapes of the profiles of fluxes (liquid water, liquid/vapour non-equilibrium phase change) simulated using the capillary model are very different from those obtained with the model considering the film flow. In this last case, the liquid/gas non-equilibrium is not noticeable as in the case of the capillary model. It seems that the film flows occult the water vapour diffusion by delaying the phase change process, therefore a lower concentration of water vapour into the soil than in the case where the capillary flow alone has been considered.

【 授权许可】

CC BY