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Open AccessArticle

A Fast Calculation Model for Local Head Loss of Non-Darcian Flow in Flexural Crack

Faculty of Geosciences and Environmental Engineering, Southwest Jiaotong University, Chengdu 610031, China
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Author to whom correspondence should be addressed.
Water 2020, 12(1), 232; https://doi.org/10.3390/w12010232
Received: 22 November 2019 / Revised: 9 January 2020 / Accepted: 10 January 2020 / Published: 14 January 2020
(This article belongs to the Section Hydraulics)
Local head loss caused by fracture intersection is often ignored because there has not been a simple method to calculate it until now. Relevant research shows that neglecting the local flow resistance leads to inaccurate results, especially when the velocity and cross angle are large. Therefore, it is necessary to find a portable method for calculation. Physical experiments of single fracture with different apertures (e = 0.77, 1.18, 1.97, 2.73 mm) were set up first to study the flow characteristics, showing obvious non-Darcian flow, which can be depicted by the Forchheimer equation when the flow velocity is sufficiently large. The computational fluid dynamics (CFD) software ANSYS FLUENT was used to build numeric simulation models. A good correlation between CFD simulation results and physical experiment results was found (Pearson’s correlation coefficient > 0.99). Then, the CFD models of flexural crack with different angles from 30° to 150° were established to compute the pressure drop of flexural crack at different velocity. It was found that the local head loss of the flexural crack varied with the bending angle, and its coefficient was expressed by the deformation of the logistic equation. By using this model, as well as a frictional head loss equation fitted by Forchheimer equation, the head loss of crossed fissures with fixed fracture aperture could be easily calculated.
Keywords: non-Darcian flow; fracture aperture; fracture shape; local head loss non-Darcian flow; fracture aperture; fracture shape; local head loss
MDPI and ACS Style

Liu, J.; Mou, C.; Song, K.; Luo, P.; He, L.; Bai, X. A Fast Calculation Model for Local Head Loss of Non-Darcian Flow in Flexural Crack. Water 2020, 12, 232.

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