Deficiency of Approximate Interblock Conductivities for Simulation of Horizontal Unsaturated Flow

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	Deficiency of Approximate Interblock Conductivities for Simulation of Horizontal Unsaturated Flow
	Pei, Y. S. ; Yang, Z. F. ; Zhang, K. J. ; Tian, B. H.
刊名	TRANSPORT IN POROUS MEDIA
	2012
卷号	91 期号:2 页码:627－647
关键词	Horizontal unsaturated flow Interblock conductivity Darcy's law Saturation Vadose zone
ISSN号	0169-3913
中文摘要	Determination of appropriate horizontal interblock conductivities approximations (k (app)) is a critical step for numerical solution of unsaturated flow by finite difference method. This study characterized the horizontal effective interblock conductivity (k (H)) and the classical k (app) by contour map. The deficiencies of the k (app) were determined by both statistical method and wetting front prediction. Mathematical expressions of the k (H) were redeveloped for three constitutive hydraulic functions. A large database including ten different k (app) formulas, three hydraulic functions, and a large range of soil texture is used to determine the deficiencies of the k (app) for simulation of horizontal unsaturated flow. Some k (app) may be either higher or lower than the k (H) since they depend on both the expression forms of the k (app) and the specific hydraulic functions. For the soil described by the Gardner function, the horizontal wetting front generated from the k (H) is almost equivalent to the analytical solution, but those predicted from the k (app) with certain errors. For the soils described by the Brooks-Corey function and the van Genuchten function, the best k (app) for approximating the k (H) were also determined, but with conversions for the soils described by the van Genuchten function. For any two k (app) that hold compatible medians, the k (app) (> k (H)) better tracks the wetting front and makes mass conservation than the k (app) (< k (H)) does. The ranking list of k (app) with respect to the quality of approximation k (H) is ultimately determined from the analysis of mass balance of the simulation based on the large database. Ten k (app) can be divided into four clusters. The logarithm mean and the arithmetic mean calculated from saturation can produce the best simulation results with relative mass balance error averagely less than 2%. Simulations conducted with harmonic mean calculated from hydraulic conductivity are mostly associated with the largest mass balance errors. Such a mean can therefore not be used to simulate horizontal water front advance, whatever the soil type and whatever the model of hydrodynamic function. It is also suggested that use of the classical k (app) in a numerical process may generate improper results, thus application of the k (H) is convincingly recommended on the prediction of horizontal wetting front.
WOS记录号	WOS:000298296700014
公开日期	2014-11-04
内容类型	期刊论文
源URL	[http://ir.rcees.ac.cn/handle/311016/7791]
专题	生态环境研究中心_环境水质学国家重点实验室
推荐引用方式 GB/T 7714	Pei, Y. S.,Yang, Z. F.,Zhang, K. J.,et al. Deficiency of Approximate Interblock Conductivities for Simulation of Horizontal Unsaturated Flow[J]. TRANSPORT IN POROUS MEDIA,2012,91(2):627－647.
APA	Pei, Y. S.,Yang, Z. F.,Zhang, K. J.,&Tian, B. H..(2012).Deficiency of Approximate Interblock Conductivities for Simulation of Horizontal Unsaturated Flow.TRANSPORT IN POROUS MEDIA,91(2),627－647.
MLA	Pei, Y. S.,et al."Deficiency of Approximate Interblock Conductivities for Simulation of Horizontal Unsaturated Flow".TRANSPORT IN POROUS MEDIA 91.2(2012):627－647.