scholarly journals A Unified Equation to Predict the Permeability of Rough Fractures via Lattice Boltzmann Simulation

Water ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 1081 ◽  
Author(s):  
Peijie Yin ◽  
Can Zhao ◽  
Jianjun Ma ◽  
Linchong Huang
Keyword(s):  
Numerical Simulation ◽  
Fluid Flow ◽  
Lattice Boltzmann ◽  
Mass Conservation ◽  
Extensive Study ◽  
Roughness Coefficient ◽  
Single Fracture ◽  
Lattice Boltzmann Simulation ◽  
Wide Range ◽  
Flow Through

In this paper, the fluid flow through rough fractures was investigated via numerical simulation based on the lattice Boltzmann method (LBM). The accuracy of LBM was validated through the numerical simulation of the parallel plate model and the verification of the mass conservation of fluid flow through rough fracture. After that, the effect of roughness on fluid flow was numerically conducted, in which, the geometry of fractures was characterized by the joint roughness coefficient (JRC), fractal dimension (D) and standard deviation (σ). It was found that the JRC cannot reflect the realistic influence of roughness on the permeability of single fracture, in which, an increase in permeability with increasing JRC has been observed at the range of 8~12 and 14~16. The reason behind this was revealed through the calculation of the root mean square of the first derivative of profile (Z2), and an equation has been proposed to estimate the permeability based on the aperture and Z2 of the fracture. The numerical simulations were further conducted on fluid flow though synthetic fractures with a wide range of D and σ. In order to unify the parameter that characterizes the roughness, Z2 was obtained for each synthetic fracture, and the corresponding relationship between permeability, aperture and Z2 was analyzed. Meanwhile, it was found that the fluid flow behaves differently with different ranges of Z2 and the critical point was found to be Z2 = 0.5. Based on extensive study, it was concluded that Z2 is a generic parameter characterizing the roughness, and the proposed equation could be used to predict the permeability for fluid flow in fracture.

scholarly journals Laboratory Simulation of Flow through Rough-Walled Microfractures under High Hydraulic Gradient

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Shuai Zhang ◽  
Wei-Guo Qiao ◽  
Yan-Zhi Li ◽  
Wei-Jie Song ◽  
Jun-Ling Qin ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Fractured Rock ◽  
Hydraulic Gradient ◽  
Strain Sensors ◽  
Surface Strain ◽  
Laboratory Simulation ◽  
Roughness Coefficient ◽  
Single Fracture ◽  
Hydraulic Pressure ◽  
Flow Through

Laboratory experiments on fluid flow through fracture are important in solving the fluid-in-rush problems that happen during the tunnel excavation. In order to study the mechanism of fluid flow through a rough-walled microfracture, fluid flow experiments were carried out and the fiber Bragg grating (FBG) strain sensors were applied to monitor the deformation of the microfracture surface during the seepage process. Considering the difficulty of collection of undisturbed rock samples from the deep locations, a methodology to simulate fluid flow through a fractured rock mass using analog materials containing a single fracture was developed. This method is easy to simulate the fluid flow through a fracture of certain aperture. Experimental data showed that Forchheimer equation could provide an excellent description of the nonlinear relationship between hydraulic gradient and flow velocity, and the variations of Forchheimer coefficients with joint roughness coefficient (JRC) were studied. It was found that the deformation of the microfracture surface subjected to seepage could be accurately captured by the quasi-distributed FBG strain sensors. The test results also demonstrated that the surface strain is significantly affected by hydraulic pressure.

LATTICE BOLTZMANN SIMULATION OF THE MOTION OF SPHERICAL PARTICLES IN STEADY POISEUILLE FLOW

2009 ◽  
Vol 20 (06) ◽  
pp. 831-846 ◽  
Author(s):  
H. H. YI ◽  
L. J. FAN ◽  
Y. Y. CHEN
Keyword(s):  
Numerical Simulation ◽  
Fluid Flow ◽  
Poiseuille Flow ◽  
Lattice Boltzmann ◽  
Cylindrical Tube ◽  
Simulation Method ◽  
Three Dimensions ◽  
Spherical Particles ◽  
Lattice Boltzmann Simulation ◽  
Simulation Results

A technique, based on the stress-integration method, for the evaluation of hydrodynamic forces on solid boundaries is proposed to simulate the solid-fluid flow systems in three dimensions in lattice Boltzmann simulations. The accuracy of the scheme is demonstrated by simulating the sphere migrating in a pressure-driven Newtonian fluid flow in a cylindrical tube. The numerical simulation results recover the Segré–Silberberg effect. Using this scheme, we investigate the behavior of a pair of spheres in a tube Poiseuille flow. Oscillatory states are observed for two spheres with different radii placed on opposite sides. The simulation results show that the present model is an effective and efficient direct numerical simulation method for simulating particle motions in fluid flows at finite Reynolds numbers in three dimensions.

Thermal Lattice Boltzmann Simulation of Rarefied Gas Flows in Nanochannels for Wide Range of Knudsen Number

2011 ◽  
Vol 403-408 ◽  
pp. 5313-5317
Author(s):  
A.H. Meghdadi Isfahani ◽  
A. Soleimani
Keyword(s):  
Lattice Boltzmann ◽  
Rarefied Gas ◽  
Gas Flows ◽  
Rarefied Gas Flows ◽  
Knudsen Numbers ◽  
Lattice Boltzmann Simulation ◽  
Wide Range ◽  
Flow Through ◽  
Boltzmann Method ◽  
Thermal Lattice Boltzmann

Using a modified Lattice Boltzmann Method (LBM), developing thermal flow through micro and nano channels has been modeled. Based on the improving of the dynamic viscosity and thermal conductivity, an effective relaxation time formulation is proposed which is able to simulate wide range of Knudsen numbers, Kn,. The results show that in spite of the standard LBM, the temperature distributions and the local Nusselt number obtained from this modified thermal LBM, agree well with the other numerical and empirical results in a wide range of Knudsen numbers.

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