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2016
employed to treat the horizontal well, including UFBC, Uniform-Head Boundary Condition
(UHBC), and Mixed-Type Boundary Condition (MTBC). The MTBC model considered bo
th kinematic and frictional effects inside the horizontal well, in which the kinematiceffect
referred to the accelerational and fluid-inflow effects. A new solution of UFBC was derived by
superimposing the point sink/source solutions along the axis of a horizontal well with a unifor
m flux distribution. New solutions of UHBC and MTBC were obtained by a hybrid analytical-
numerical method, and an iterative method was proposed to determine the well discretization
required for achieving sufficiently accurate results. This study showed that the differences
among the UFBC, UHBC, and MTBC solutions were obvious near the well screen, decreased
with distance from thewell, and became negligible near the constant-head boundary. The
relationship between the flow rate and the drawdown was nonlinear for the MTBC solution,
while it was linear for the UFBC and UHBC solutions.
论文链接：https://doi.org/10.1002/2015WR018252
4. Effects of particle diameter on flow characteristics in sand columns
作 者：Li, ZX ( 李仲夏，博士生 ) [ 1 ] ; Wan, JW ( 万军伟 ) [ 1 ] ; Huang, K ( 黄琨 )
[ 1 ]
[ 1 ] ; Chang, W (Chang, Wei) ; He, Y (He, You) [ 1 ]
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER 卷 : 104 页 : 533-536 出版
年 : JAN 2017
摘 要：This work aims to investigate the effects of particle size on flow regime
s and validation of Darcy law. Experiments were conducted in sand columnswith five di
fferent particle sizes of silica sand in mean diameter 1.075 mm, 1.475 mm, 1.85 mm,
2.5 mm and 3.17 mm. Both pre-Darcy flow and post Darcy flow were identified but no
obvious linear flow was observed, the Reynolds number of two flow regime are different
with different grain sizes. Relative error was used to evaluate the experimental data and
obtain that the values of Reynolds number at the demarcation point are 3.90, 7.08, 9.1
and 10.78. The values of Reynolds number of two flow regime increased gradually as th
e particle diameter increased. A new Reynolds number defined as ratio of inertia term
and viscous term in Forchheimer equation can lead to a single criterion for determining
the limit of validity of Darcy law. The recommended critical Reynolds number for non-
Darcy flow is equal to 0.1, where the error of neglecting inertial effects in the hydraulic
gradient will be less than 10%. (C) 2016 Elsevier Ltd. All rights reserved.
论文链接：https://doi.org/10.1016/j.ijheatmasstransfer.2016.08.085
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