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Article

Nonlinear Flow Characteristics of a System of Two Intersecting Fractures with Different Apertures

1
State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Xuzhou 221116, China
2
School of Engineering, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 8528521, Japan
3
State Key Laboratory of Mining Disaster Prevention and Control Co-Founded by Shandong Province and the Ministry of Science and Technology, Shandong University of Science and Technology, Qingdao 266510, China
*
Author to whom correspondence should be addressed.
Processes 2018, 6(7), 94; https://doi.org/10.3390/pr6070094
Received: 27 June 2018 / Revised: 11 July 2018 / Accepted: 12 July 2018 / Published: 20 July 2018
(This article belongs to the Section Advanced Digital and Other Processes)
The nonlinear flow regimes of a crossed fracture model consisting of two fractures have been investigated, in which the influences of hydraulic gradient, surface roughness, intersecting angle, and scale effect have been taken into account. However, in these attempts, the aperture of the two crossed fractures is the same and effects of aperture ratio have not been considered. This study aims to extend their works, characterizing nonlinear flow through a system of two intersecting fractures with different apertures. First, three experiment models with two fractures having different apertures were established and flow tests were carried out. Then, numerical simulations by solving the Navier-Stokes equations were performed and the results compared with the experiment results. Finally, the effects of fracture aperture on the critical pressure difference and the ratio of hydraulic aperture to mechanical aperture were systematically analyzed. The results show that the numerical simulation results agree well with those of the fluid flow tests, which indicates that the visualization techniques and the numerical simulation code are reliable. With the increment of flow rate, the pressure difference increases first linearly and then nonlinearly, which can be best fitted using Forchheimer’s law. The two coefficients in Forchheimer’s law decrease with the increasing number of outlets. When increasing fracture aperture from 3 mm to 5 mm, the critical pressure difference increases significantly. However, when continuously increasing fracture aperture from 5 mm to 7 mm, the critical pressure difference changes are negligibly small. The ratio of hydraulic aperture to mechanical aperture decreases more significantly for a fracture that has a larger aperture. Increasing fracture aperture from 5 mm to 7 mm, that has a negligibly small effect on the critical pressure difference will however significantly influence the ratio of hydraulic aperture to mechanical aperture. View Full-Text
Keywords: nonlinear flow; Navier-Stokes equations; critical pressure difference; hydraulic aperture; mechanical aperture nonlinear flow; Navier-Stokes equations; critical pressure difference; hydraulic aperture; mechanical aperture
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MDPI and ACS Style

Liu, R.; Jiang, Y.; Jing, H.; Yu, L. Nonlinear Flow Characteristics of a System of Two Intersecting Fractures with Different Apertures. Processes 2018, 6, 94. https://doi.org/10.3390/pr6070094

AMA Style

Liu R, Jiang Y, Jing H, Yu L. Nonlinear Flow Characteristics of a System of Two Intersecting Fractures with Different Apertures. Processes. 2018; 6(7):94. https://doi.org/10.3390/pr6070094

Chicago/Turabian Style

Liu, Richeng, Yujing Jiang, Hongwen Jing, and Liyuan Yu. 2018. "Nonlinear Flow Characteristics of a System of Two Intersecting Fractures with Different Apertures" Processes 6, no. 7: 94. https://doi.org/10.3390/pr6070094

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