TORTUOSITY–POROSITY RELATIONSHIP IN TWO-DIMENSIONAL FRACTAL MODEL OF POROUS MEDIA

Fractals ◽  
2013 ◽  
Vol 21 (02) ◽  
pp. 1350013 ◽  
Author(s):  
SELLY FERANIE ◽  
FOURIER D. E. LATIEF
Keyword(s):  
Porous Media ◽  
Fractal Dimension ◽  
Lattice Gas ◽  
Empirical Relation ◽  
Fractal Model ◽  
Flow Equation ◽  
Two Dimensional ◽  
Porous Substance ◽  
Numerical Result ◽  
Random Algorithm

Tortuosity (τ) of two-dimensional fractal model of porous media is investigated to study their relationship with porosity. Square full-walk technique is applied to obtain τ in a two-dimensional fractal model of porous substance constructed by Randomized Sierspinski Carpets. The numerical result is in good agreement with previous results and empirical relation between tortuosity and porosity given by τ ~ p(1 - ϕ) + 1 that was found by other using Lattice Gas Automata method for solving flow equation on two-dimensional porous substance constructed by randomly placed rectangles of equal size and with unrestricted overlap. Average tortuosity of the flow path decreases linearly as fractal dimension of pore increases at each fractal iteration. Both fractal dimension and iteration give almost the same linearly tortuosity–porosity relation. The type of random algorithm for constructing Randomized Sierspinski Carpets has no significant influence on the tortuosity–porosity relation.

A FRACTAL MODEL FOR PREDICTING OXYGEN EFFECTIVE DIFFUSIVITY OF POROUS MEDIA WITH ROUGH SURFACES UNDER DRY AND WET CONDITIONS

Fractals ◽  
2021 ◽  
pp. 2150076
Author(s):  
BOQI XIAO ◽  
QIWEN HUANG ◽  
BOMING YU ◽  
GONGBO LONG ◽  
HANXIN CHEN
Keyword(s):  
Porous Media ◽  
Fractal Dimension ◽  
Oxygen Diffusion ◽  
Water Saturation ◽  
Rough Surfaces ◽  
Effective Diffusivity ◽  
Fractal Model ◽  
Relative Roughness ◽  
Oxygen Diffusivity ◽  
Dry And Wet Conditions

Oxygen diffusion in porous media (ODPM) with rough surfaces (RS) under dry and wet conditions is of great interest. In this work, a novel fractal model for the oxygen effective diffusivity of porous media with RS under dry and wet conditions is proposed. The proposed fractal model is expressed in terms of relative roughness, the water saturation, fractal dimension for tortuosity of tortuous capillaries, fractal dimension for pores, and porosity. It is observed that the normalized oxygen diffusivity decreases with increasing relative roughness and fractal dimension for capillary tortuosity. It is found that the normalized oxygen diffusivity increases with porosity and fractal dimension for pore area. Besides, it is seen that that the normalized oxygen diffusivity under wet condition decreases with increasing water saturation. The determined normalized oxygen diffusivity is in good agreement with experimental data and existing models reported in the literature. With the proposed analytical fractal model, the physical mechanisms of oxygen diffusion through porous media with RS under dry and wet conditions are better elucidated. Every parameter in the proposed fractal model has clear physical meaning, with no empirical constant.

Fractal Model for Thermal Conductivity of Wetting, Fibrous Porous Media

2012 ◽  
Vol 496 ◽  
pp. 12-16
Author(s):  
Fang Long Zhu ◽  
De Hong Xia ◽  
Yu Zhou
Keyword(s):  
Thermal Conductivity ◽  
Porous Media ◽  
Fractal Dimension ◽  
Effective Thermal Conductivity ◽  
Fractal Model ◽  
Self Similarity ◽  
Conductivity Model ◽  
Electrical Analogy ◽  
Fibrous Porous Media ◽  
Thermal Conductivity Model

The current paper deals with the fractal effective thermal conductivity model for fibrous porous media containing unsaturated water moisture. The model is based on the thermal-electrical analogy and statistical self-similarity of porous media. The fractal effective thermal conductivity model can be expressed as a function of the pore structure (fractal dimension) and architectural parameters of porous media. It is expected that the model will be helpful in the evaluation of thermal comfort for textiles in the whole range of porosity.

A NEW RELATIVE PERMEABILITY MODEL OF UNSATURATED POROUS MEDIA BASED ON FRACTAL THEORY

Fractals ◽  
2020 ◽  
Vol 28 (01) ◽  
pp. 2050002
Author(s):  
KE CHEN ◽  
HE CHEN ◽  
PENG XU
Keyword(s):  
Experimental Data ◽  
Porous Media ◽  
Fractal Dimension ◽  
Multiphase Flow ◽  
Relative Permeability ◽  
Volume Fraction ◽  
Fractal Model ◽  
Accurate Estimation ◽  
Unsaturated Porous Media ◽  
Flow Through

The multiphase flow through unsaturated porous media and accurate estimation of relative permeability are significant for oil and gas reservoir, grounder water resource and chemical engineering, etc. A new fractal model is developed for the multiphase flow through unsaturated porous media, where multiscale pore structure is characterized by fractal scaling law and the trapped water in the pores is taken into account. And the analytical expression for relative permeability is derived accordingly. The relationships between the relative permeability and capillary head as well as saturation are determined. The proposed model is validated by comparison with 14 sets of experimental data, which indicates that the fractal model agrees well with experimental data. It has been found that the proposed fractal model shows evident advantages compared with BC-B model and VG-M model, especially for the porous media with fine content and texture. Further calculations show that water permeability decreases as the fractal dimension increases under fixed saturation because the cumulative volume fraction of small pores increases with the increment of the fractal dimension. The present fractal model for the relative permeability may be helpful to understand the multiphase flow through unsaturated porous media.

A DIFFUSIVITY MODEL FOR GAS DIFFUSION IN DRY POROUS MEDIA COMPOSED OF CONVERGING–DIVERGING CAPILLARIES

Fractals ◽  
2016 ◽  
Vol 24 (03) ◽  
pp. 1650034 ◽  
Author(s):  
SHIFANG WANG ◽  
TAO WU ◽  
YONGJU DENG ◽  
QIUSHA ZHENG ◽  
QIAN ZHENG
Keyword(s):  
Experimental Data ◽  
Porous Media ◽  
Fractal Dimension ◽  
Fractal Theory ◽  
Knudsen Diffusion ◽  
Fractal Model ◽  
Gas Diffusion ◽  
Pore Area ◽  
Relative Diffusivity ◽  
Fluctuation Amplitude

Gas diffusion in dry porous media has been a hot topic in several areas of technology for many years. In this paper, a diffusivity model for gas diffusion in dry porous media is developed based on fractal theory and Fick’s law, which incorporates the effects of converging–diverging pores and tortuous characteristics of capillaries as well as Knudsen diffusion. The effective gas diffusivity model is expressed as a function of the fluctuation amplitude of the capillary cross-section size variations, the porosity, the pore area fractal dimension and the tortuosity fractal dimension. The results show that the relative diffusivity decreases with the increase of the fluctuation amplitude and increases with the increase of pore area fractal dimension. To verify the validity of the present model, the relative diffusivity from the proposed fractal model is compared with the existing experimental data as well as two available models of Bruggeman and Shou. Our proposed diffusivity model with pore converging–diverging effect included is in good agreement with reported experimental data.

A FRACTAL MODEL FOR KOZENY–CARMAN CONSTANT AND DIMENSIONLESS PERMEABILITY OF FIBROUS POROUS MEDIA WITH ROUGHENED SURFACES

Fractals ◽  
2019 ◽  
Vol 27 (07) ◽  
pp. 1950116 ◽  
Author(s):  
BOQI XIAO ◽  
YIDAN ZHANG ◽  
YAN WANG ◽  
GUOPING JIANG ◽  
MINGCHAO LIANG ◽  
...  
Keyword(s):  
Porous Media ◽  
Fractal Dimension ◽  
Fluid Transport ◽  
Fractal Theory ◽  
Fractal Model ◽  
Physical Mechanisms ◽  
Relative Roughness ◽  
Fibrous Porous Media ◽  
Effect Of Surface ◽  
Good Agreement

In this paper, fluid transport through fibrous porous media is studied by the fractal theory with a focus on the effect of surface roughness of capillaries. A fractal model for Kozeny–Carman (KC) constant and dimensionless permeability of fibrous porous media with roughened surfaces is derived. The determined KC constant and dimensionless permeability of fibrous porous media with roughened surfaces are in good agreement with available experimental data and existing models reported in the literature. It is found that the KC constant of fibrous porous media with roughened surfaces increases with the increase of relative roughness, porosity, area fractal dimension of pore and tortuosity fractal dimension, respectively. Besides, it is seen that the dimensionless permeability of fibrous porous media with roughened surfaces decreases with increasing relative roughness and tortuosity fractal dimension. However, it is observed that the dimensionless permeability of fibrous porous media with roughened surfaces increases with porosity. With the proposed fractal model, the physical mechanisms of fluids transport through fibrous porous media are better elucidated.

scholarly journals A Numerical Study on Gas Flow through Anisotropic Sierpinski Carpet with Slippage Effect

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Shuxia Qiu ◽  
Lipei Zhang ◽  
Zhenhua Tian ◽  
Zhouting Jiang ◽  
Mo Yang ◽  
...  
Keyword(s):  
Porous Media ◽  
Fractal Dimension ◽  
Gas Flow ◽  
Gas Permeability ◽  
Fractal Model ◽  
Numerical Results ◽  
Pore Scale ◽  
Gas Slippage ◽  
Slippage Effect ◽  
Flow Through

A pore-scale model has been developed to study the gas flow through multiscale porous media based on a two-dimensional self-similar Sierpinski carpet. The permeability tensor with slippage effect is proposed, and the effects of complex configurations on gas permeability have been discussed. The present fractal model has been validated by comparison with theoretical models and available experimental data. The numerical results show that the flow field and permeability of the anisotropic Sierpinski model are different from that of the isotropic model, and the anisotropy of porous media can enhance gas permeability. The gas permeability of porous media increases with the increment of porosity, while it decreases with increased pore fractal dimension under fixed porosity. Furthermore, the gas slippage effect strengthens as the pore fractal dimension decreases. However, the relationship between the gas slippage effect and porosity is a nonmonotonic decreasing function because reduced pore size and enhanced flow resistance may be simultaneously involved with decreasing porosity. The proposed pore-scale fractal model can present insights on characterizing complex and multiscale structures of porous media and understanding gas flow mechanisms. The numerical results may provide useful guidelines for the applications of porous materials in oil and gas engineering, hydraulic engineering, chemical engineering, thermal power engineering, food engineering, etc.

A NUMERICAL STUDY ON FRACTAL DIMENSIONS OF CURRENT STREAMLINES IN TWO-DIMENSIONAL AND THREE-DIMENSIONAL PORE FRACTAL MODELS OF POROUS MEDIA

Fractals ◽  
2015 ◽  
Vol 23 (01) ◽  
pp. 1540012 ◽  
Author(s):  
WEI WEI ◽  
JIANCHAO CAI ◽  
XIANGYUN HU ◽  
PING FAN ◽  
QI HAN ◽  
...  
Keyword(s):  
Porous Media ◽  
Fractal Dimension ◽  
Numerical Study ◽  
Three Dimensional ◽  
Fractal Dimensions ◽  
Simple Relation ◽  
Two Dimensional ◽  
Random Walker ◽  
Fractal Models ◽  
Novel Method

The fractal dimension of random walker (FDRW) is an important parameter for description of electrical conductivity in porous media. However, it is somewhat empirical in nature to calculate FDRW. In this paper, a simple relation between FDRW and tortuosity fractal dimension (TFD) of current streamlines is derived, and a novel method of computing TFD for different generations of two-dimensional Sierpinski carpet and three-dimensional Sierpinski sponge models is presented through the finite element method, then the FDRW can be accordingly predicted; the proposed relation clearly shows that there exists a linear relation between pore fractal dimension (PFD) and TFD, which may have great potential in analysis of transport properties in fractal porous media.

scholarly journals Lattice-Gas Simulations of Ternary Amphiphilic Fluid Flow in Porous Media

1998 ◽  
Vol 09 (08) ◽  
pp. 1479-1490 ◽  
Author(s):  
P. V. Coveney ◽  
J.-B. Maillet ◽  
J. L. Wilson ◽  
P. W. Fowler ◽  
O. Al-Mushadani ◽  
...  
Keyword(s):  
Porous Media ◽  
Boundary Conditions ◽  
Single Phase ◽  
Lattice Gas ◽  
Flow In Porous Media ◽  
Two Dimensional ◽  
Slip Boundary Conditions ◽  
Dimensional Lattice ◽  
Slip Boundary ◽  
Saturated Rock

We develop our existing two-dimensional lattice-gas model to simulate the flow of single phase, binary immiscible and ternary amphiphilic fluids. This involves the inclusion of fixed obstacles on the lattice, together with the inclusion of "no-slip" boundary conditions. Here we report on preliminary applications of this model to the flow of such fluids within model porous media. We also construct fluid invasion boundary conditions, and the effects of invading aqueous solutions of surfactant on oil-saturated rock during imbibition and drainage are described.

FRACTAL MODEL OF GAS DIFFUSION IN FRACTURED POROUS MEDIA

Fractals ◽  
2018 ◽  
Vol 26 (03) ◽  
pp. 1850035 ◽  
Author(s):  
QIAN ZHENG ◽  
JINTU FAN ◽  
XIANGPENG LI ◽  
SHIFANG WANG
Keyword(s):  
Porous Media ◽  
Diffusion Coefficient ◽  
Fractal Dimension ◽  
Gas Transport ◽  
Fractal Model ◽  
Gas Diffusion ◽  
Diameter Ratio ◽  
Fractured Porous Media ◽  
Length Ratio ◽  
Branching Angle

Understanding gas transport behavior though fractured porous media is essential in many fields including fiber science, energy science, soil science, environmental engineering, chemical engineering, etc. In this paper, a fractal model is developed to characterize gas diffusion through fractured porous media, where a bundle of fractal-like tree branching networks is used to represent the fracture system according to fractal scaling laws. The analytical expression for relative gas diffusion coefficient of fractured porous media is derived. The proposed fractal model has been validated by the available experimental data and empirical correlations. From the parametrical study, it can be seen that structural parameters of fractured porous media (for example porosity, the fractal dimension, the diameter ratio, the length ratio and the branching angle) have a significant effect on equivalent gas transport properties. Gas relative diffusion coefficient has a positive correlation with the porosity, the pore size fractal dimension, or the diameter ratio, whereas it has a negative correlation with the length ratio, the branching levels, or the branching angle. The proposed fractal model does not only shed light on gas transport physics of fractured porous media, but also reveals more mechanisms than experimental measurements.

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