Effects of surface roughness on the heat transfer characteristics of water flow through a single granite fracture

He, Yanlin; Bai, Bing; Hu, Shaobin; Li, Xiaochun

doi:10.1016/j.compgeo.2016.09.002

Cited by 72 publications

(28 citation statements)

References 19 publications

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“…Besides, the rougher fracture surface contributes to the longer flow paths that a particle moves within fractures, resulting in a weaker conductivity/permeability if the same pressure difference is applied on the opposing boundaries [36,77,122,123]. The previous works have shown that the fracture surface roughness, especially the secondary roughness, plays a significant role on the nonlinear flow properties of rock fractures, because the eddy flow occurs due to the surface roughness [79].…”

Section: Effect Of Fracture Surface Roughnessmentioning

confidence: 99%

A Review of Critical Conditions for the Onset of Nonlinear Fluid Flow in Rock Fractures

Jiang

2017

Geofluids

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Selecting appropriate governing equations for fluid flow in fractured rock masses is of special importance for estimating the permeability of rock fracture networks. When the flow velocity is small, the flow is in the linear regime and obeys the cubic law, whereas when the flow velocity is large, the flow is in the nonlinear regime and should be simulated by solving the complex NavierStokes equations. The critical conditions such as critical Reynolds number and critical hydraulic gradient are commonly defined in the previous works to quantify the onset of nonlinear fluid flow. This study reviews the simplifications of governing equations from the Navier-Stokes equations, Stokes equation, and Reynold equation to the cubic law and reviews the evolutions of critical Reynolds number and critical hydraulic gradient for fluid flow in rock fractures and fracture networks, considering the influences of shear displacement, normal stress and/or confining pressure, fracture surface roughness, aperture, and number of intersections. This review provides a reference for the engineers and hydrogeologists especially the beginners to thoroughly understand the nonlinear flow regimes/mechanisms within complex fractured rock masses.

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Section: Effect Of Fracture Surface Roughnessmentioning

confidence: 99%

A Review of Critical Conditions for the Onset of Nonlinear Fluid Flow in Rock Fractures

Jiang

2017

Geofluids

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“…Thus, the accuracy of the 3D coupled hydrothermal model has been further verified. An important reason for the error is that the fracture surface in the experiment is rough and wavy, 41 which is different from the fracture surface in the numerical model with a constant aperture. Another possible reason is that the accuracy of the experimental data may be limited.…”

Section: Numerical and Experimental Resultsmentioning

confidence: 96%

“…The calculation parameters include the fluid density ρ f = 1000 kg/m 3 , the dynamic viscosity coefficient of the fluid μ = 0.001 Pa second, the specific heat of the fluid C f = 4200 J/(kg °C), the thermal conductivity coefficient of the fluid k f = 0.6 W/(m °C), the density of the rock specimen ρ s = 2360 J/(kg °C), the specific heat of the rock specimen C s = 1015 J/(kg °C), and the thermal conductivity coefficient of the rock specimen k s = 2 W/(m °C). The other parameters (fracture aperture, fluid velocity, and fluid temperature at the inlet) are obtained directly from the experimental data, as shown in Table . Two values for the heat exchange coefficient h are used: (1) the average heat transfer coefficient and (2) the coefficient calculated according to the empirical formula h = 543 v 0.9 in Zhao and Tso, where v is the fluid flow velocity.…”

Section: Experimental Verification Examplementioning

confidence: 99%

FDEM‐TH3D: A three‐dimensional coupled hydrothermal model for fractured rock

Yan

Jiao

2018

Num Anal Meth Geomechanics

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Summary This paper proposes a three‐dimensional coupled hydrothermal model for fractured rock based on the finite‐discrete element method to simulate fluid flow and heat transport. The 3D coupled hydrothermal model is composed of three main parts: a heat conduction model for the rock matrix, a heat transfer model for the fluid in the fractures (including heat conduction and heat convection), and a heat exchange model between the rock matrix and the fluid in the fractures. Four examples with analytical solutions are provided to verify the model. A heat exchange experiment of circulating water in a cylindrical granite sample with one fracture is simulated. The simulation results agree well with the experimental results. The effects of the fracture aperture, fluid viscosity, and pressure difference on the heat exchange between the fluid and rock are studied. Finally, an application concerned with heat transport and fluid flow in fractured rock is presented. The simulation results indicate that the 3D fully coupled hydrothermal model can capture the fluid flow and temperature evolution of rocks and fluids.

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“…In rock mechanics laboratories, rock samples are tested under various stress conditions that mimic different depths and stress regimes in the crust. The in situ interactions such as terrestrial heat and fluid flow can also be considered as the process of thermal-mechanical coupling or fluid-solid coupling (He et al, 2016;Li et al, 2017;Luo et al, 2016). Most of such studies concentrated on observing and characterizing the cracks, or elucidating the influence of flaw arrays on the coalescence process, which throw light on the mechanisms of crack nucleation and propagation from preexisting fractures.…”

Section: Fracture Coalescence At Various Scalesmentioning

confidence: 99%

Recognition of Mesoscale Strike‐Slip En Echelon Faults From 2‐D Nonporous Models

Wong

Zhang

2019

JGR Solid Earth

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Growth and connection of preexisting fractures have been recognized as the driving mechanism of rock fracturing. This paper aims at throwing light on the geological implications of the fracturing behavior in pre-cracked rock observed in rock mechanics-oriented experiments, by numerical interpretation on the interaction of en echelon fractures. To properly simulate grain crushing involved in cataclastic deformation of nonporous rocks, a sophisticated numerical scheme incorporating rock morphology and crystallography into the grain-based model is proposed. In line with a previous experimental study, seven grain-based models with different configurations of en echelon flaws are numerically tested under uniaxial compression. The key results are (1) evaluation of the influences of preexisting flaws on mechanical properties and damage degree of the host rock, (2) visualization of the microfracture process zone into visible cracks, and (3) generalization of three different patterns of major fracture formation from en echelon fractures, during which the ratio of the number of intergranular to intragranular microcracks is used for evaluation of the cataclastic deformation process and the stress level. Based on the numerical results, we provide valuable interpretation on (1) the field occurrence of strike-slip fault system with typical fracturing features, focusing on the effects of the sense of left or right stepping and the degrees of separation/overlap of the master fractures, and (2) three different mechanisms of fault formation from preexisting fractures. As an initial attempt to relate rock fracturing observed in laboratory experiments with the field occurrence, capabilities and limitations of this study are also presented.

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Effects of surface roughness on the heat transfer characteristics of water flow through a single granite fracture

Cited by 72 publications

References 19 publications

A Review of Critical Conditions for the Onset of Nonlinear Fluid Flow in Rock Fractures

A Review of Critical Conditions for the Onset of Nonlinear Fluid Flow in Rock Fractures

FDEM‐TH3D: A three‐dimensional coupled hydrothermal model for fractured rock

Recognition of Mesoscale Strike‐Slip En Echelon Faults From 2‐D Nonporous Models

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