Effects of Hydraulic Gradient, Intersecting Angle, Aperture, and Fracture Length on the Nonlinearity of Fluid Flow in Smooth Intersecting Fractures: An Experimental Investigation

Wu, Zhijun; Fan, L.F.; Zhao, Shihe

doi:10.1155/2018/9352608

Cited by 19 publications

(4 citation statements)

References 46 publications

(69 reference statements)

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“…The present study extends the works of Li et al [32] and Wu et al [33] to study the nonlinear flow properties of a crossed fracture model consisting of two fractures with different apertures. First, three experiment models, with two fractures having different apertures, were established and flow tests were carried out.…”

Section: Introductionsupporting

confidence: 74%

“…Kosakowski and Berkowitz [21] depicted that the fluid flow transits from the linear regime to the nonlinear regime when Re > 10, by numerically solving the complex Navier-Stokes equations. The influences of hydraulic gradient, surface roughness, intersecting angle, and scale effect on the nonlinear flow characteristics at the intersections have been both experimentally and numerically investigated [31][32][33]. They found that the nonlinearity can be negligible when the ratio of fracture aperture to fracture length is smaller than 0.001, and the hydraulic gradient that is less than 0.001 plays a sufficiently small role on the nonlinear flow.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2018

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Abstract: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.

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Section: Introductionsupporting

confidence: 74%

Section: Introductionmentioning

confidence: 99%

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

et al. 2018

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“…In the process of underground engineering, many rock hydraulics problems are related to the rock fracture pathway. Under the interaction of artificial engineering disturbance stress, in situ stress, and groundwater seepage pressure, the seepage behavior of groundwater in rock mass fractures affects the stability of fractured rock masses in engineering activities [1,2]. The safety of human engineering activities and the adverse effects of the geological environment on engineering activities are also often affected by the seepage behavior of fluids in rock fractures [3].…”

Section: Introductionmentioning

confidence: 99%

Evaluating the Influence of Fracture Roughness and Tortuosity on Fluid Seepage Based on Fluid Seepage Experiments

Shuai

Zhang

et al. 2022

Applied Sciences

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The roughness and tortuosity of fractures are essential parameters affecting the fluid flow in a jointed rock mass. This paper investigates the influence of fracture roughness and tortuosity on fluid seepage behavior. A rough fracture surface was characterized by means of three-dimensional scanning and three-reconstruction technology, and the roughness and tortuosity of rock fractures were calculated. Hydraulic tests were conducted on deformed sandstone fractures with a self-made fracture seepage device, and the variation in the seepage flow was analyzed in rough fractures. The experimental results showed that the seepage flow of fluid decreased non-linearly with the increase in fracture roughness. Under different normal pressures, the friction resistance coefficient and tortuous resistance coefficient decreased with the increase in the Reynolds number. The friction resistance coefficient model and tortuous resistance coefficient model were used to quantitatively analyze the influence of fracture tortuosity and roughness on fluid flow, respectively. A modified model of the frictional resistance coefficient, considering fracture tortuosity and roughness, was established, which clearly expresses the law that with the increase in fracture tortuosity and roughness, the seepage flow of fluid decreases, and the head loss increases. The results of this research can provide a theoretical and experimental basis for studying fluid seepage behavior in deformed sandstone fractures.

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“…On account of the fact that the computational cost of applying rough texture on rock fractures is high, most earlier studies have simplified the problem by considering smooth parallel surfaces (Lemieux and Sudicky 2010, Wu et al 2018, Aghajannezhad et al 2020. The fluid flow behaviour in a single natural fracture has been thoroughly investigated in the last two decades solving the full NSE and Reynolds equation (Zou et al 2015, 2017a, Lee and Babadagli 2021.…”

Section: Introductionmentioning

confidence: 99%

The effects of surface roughness on the flow in multiple connected fractures

Aghajannezhad¹,

Sellier²

2022

Fluid Dyn. Res.

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We present a novel computationally efficient approach for investigating the effect of surface roughness on the fluid flow in discrete fracture networks at low Reynolds number. The effect of parallel and series fracture arrangements on the flow rate and hydraulic resistance was studied numerically by patching Hele-Shaw (HS) cells to represent the network. In this analysis, the impact of surface roughness was studied in different arrangements of the network. For this aim, four models with different sequences of fracture connections were studied. The validity of the models was assessed by comparing the results with solutions of the full Navier-Stokes equations (NSE). The approximate hydraulic resistance and flow rate calculated by the HS method were found to be in good agreement with the NSE (less than 7% deviation). Results suggest a quadratic relationship between the network hydraulic resistance and the joint roughness coefficient (JRC). Notably, an increase in surface roughness caused a growth in hydraulic resistance and a fall in flow rate. Further insight was provided by drawing an analogy between resistors in electrical circuits and fractures in networks.

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Effects of Hydraulic Gradient, Intersecting Angle, Aperture, and Fracture Length on the Nonlinearity of Fluid Flow in Smooth Intersecting Fractures: An Experimental Investigation

Cited by 19 publications

References 46 publications

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

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

Evaluating the Influence of Fracture Roughness and Tortuosity on Fluid Seepage Based on Fluid Seepage Experiments

The effects of surface roughness on the flow in multiple connected fractures

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