The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Renduo Zhang - One of the best experts on this subject based on the ideXlab platform.
-
evaluation of soil water retention curve with the pore solid Fractal Model
Geoderma, 2005Co-Authors: Guanhua Huang, Renduo ZhangAbstract:Abstract Empirical Models have been developed to describe the soil water retention curve (SWRC). Applications of the Fractal theory may provide a useful tool to fill the gap between the use of empirical Models and physical interpretation of their parameters. Especially a more generalized Model for the SWRC has been developed based on the pore–solid Fractal (PSF) distribution. The PSF Model covers several existing Models as its special cases and theoretically provides a direct way to estimate the SWRC Fractal dimension from particle size distributions (PSDs). The first objective of this study was to evaluate the SWRC with the PSF distribution using more than 400 data sets of PSD and SWRC. The second objective was to establish a relationship between the Fractal dimension and soil texture. Analyses of the data sets showed that the Fractal dimension values estimated using the PSD data were consistently smaller than those estimated using the SWRC data. Therefore, using the Fractal dimension from PSD to predict the SWRC will result in underestimation. To resolve the problem, the soil data sets of PSD and SWRC were used to establish relationships between the Fractal dimensions in the PSF Model of SWRC and soil clay content as well as soil texture class. Independent SWRC data sets were used to test the methods. Predicted results using the PSF Model of SWRC with the Fractal dimension estimated using clay content or soil texture class were compared with the measured soil water retention data. Linear regressions of the predicted and measured SWRC showed good agreement for relatively fine texture soils with the coefficients of determination (r2) of 0.940.
-
testing the pore solid Fractal Model for the soil water retention function
Soil Science Society of America Journal, 2005Co-Authors: Kang Wang, Renduo Zhang, Fuqin WangAbstract:The soil water retention curve is an important hydraulic function for the study of flow transport processes in unsaturated soils. To accurately describe and interpret the hydraulic property, a general soil water retention function was developed based on the pore-solid Fractal (PSF) Model. The objective of this study was to evaluate the general soil water retention function using data of 65 soils and to compare the PSF function with its special cases, that is, three other soil water retention functions. Defined from the parameters of the PSF, an index of β/θ, was used to quantify the relationship between the PSF and the other soil water retention functions. The PSF function fit all the data sets well, whereas the other retention functions only matched the retention data for some soils, ranging from 11 to 72% of the tested soils. Directly fitting these functions with the data sets showed that for 30 to 40% of the tested soils, these functions gave poorer results than the PSF.
Boqi Xiao - One of the best experts on this subject based on the ideXlab platform.
-
a Fractal Model for capillary flow through a single tortuous capillary with roughened surfaces in fibrous porous media
Fractals, 2021Co-Authors: Boqi Xiao, Qiwen Huang, Hanxin Chen, Xubing Chen, Gongbo LongAbstract:In this paper, a Fractal Model for capillary flow through a single tortuous capillary with roughened surfaces in fibrous porous media is derived. The determined imbibition height and imbibition mas...
-
a Fractal Model for kozeny carman constant and dimensionless permeability of fibrous porous media with roughened surfaces
Fractals, 2019Co-Authors: Boqi Xiao, Xubing Chen, Yidan Zhang, Yan Wang, Guoping Jiang, Mingchao Liang, Gongbo LongAbstract: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) c...
-
a Fractal Model for water flow through unsaturated porous rocks
Fractals, 2018Co-Authors: Boqi Xiao, Hanxin Chen, Gongbo Long, Xian Zhang, Wei Wang, Hao Kang, Wen RenAbstract:In this work, considering the effect of porosity, pore size, saturation of water and tortuosity Fractal dimension, an analytical Model for the capillary pressure and water relative permeability is derived in unsaturated porous rocks. Besides, the formulas of calculating the capillary pressure and water relative permeability are given by taking into account the Fractal distribution of pore size and tortuosity of capillaries. It can be seen that the capillary pressure for water phase decreases with the increase of saturation in unsaturated porous rocks. It is found that the capillary pressure for water phase decreases as the tortuosity Fractal dimension decreases. It is further seen that the capillary pressure for water phase increases with the decrease of porosity, and at low porosity, the capillary pressure increases sharply with the decrease of porosity. Besides, it can be observed that the water relative permeability increases with the increase of saturation in unsaturated porous rocks. This predicted t...
-
developing a novel form of thermal conductivity of nanofluids with brownian motion effect by means of Fractal geometry
Powder Technology, 2013Co-Authors: Boqi Xiao, Yi Yang, Lingxia ChenAbstract:Abstract Considering the effect of Brownian motion of nanoparticles, an analytical Model for effective thermal conductivity of nanofluids is obtained. The formula of calculating effective thermal conductivity of nanofluids is given by taking into account the Fractal distribution of nanoparticles. In the present approach, the proposed Model is explicitly related to the thermal conductivities of the base fluids and the nanoparticles, the average diameter of nanoparticles, the nanoparticle concentration, the Fractal dimension of nanoparticles and physical properties of fluids. It is found that the effective thermal conductivity of nanofluids increases with increasing of the concentration of nanoparticles. And the effective thermal conductivity of nanofluids for the smaller size of nanoparticles is larger than the bigger size at given concentration. A good agreement between the proposed Model predictions and experimental data is found. The validity of the Fractal Model for effective thermal conductivity of nanofluids is thus verified. The proposed Fractal Model can reveal the physical mechanisms of heat transfer for nanofluids.
Gongbo Long - One of the best experts on this subject based on the ideXlab platform.
-
a Fractal Model for capillary flow through a single tortuous capillary with roughened surfaces in fibrous porous media
Fractals, 2021Co-Authors: Boqi Xiao, Qiwen Huang, Hanxin Chen, Xubing Chen, Gongbo LongAbstract:In this paper, a Fractal Model for capillary flow through a single tortuous capillary with roughened surfaces in fibrous porous media is derived. The determined imbibition height and imbibition mas...
-
a Fractal Model for kozeny carman constant and dimensionless permeability of fibrous porous media with roughened surfaces
Fractals, 2019Co-Authors: Boqi Xiao, Xubing Chen, Yidan Zhang, Yan Wang, Guoping Jiang, Mingchao Liang, Gongbo LongAbstract: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) c...
-
a Fractal Model for water flow through unsaturated porous rocks
Fractals, 2018Co-Authors: Boqi Xiao, Hanxin Chen, Gongbo Long, Xian Zhang, Wei Wang, Hao Kang, Wen RenAbstract:In this work, considering the effect of porosity, pore size, saturation of water and tortuosity Fractal dimension, an analytical Model for the capillary pressure and water relative permeability is derived in unsaturated porous rocks. Besides, the formulas of calculating the capillary pressure and water relative permeability are given by taking into account the Fractal distribution of pore size and tortuosity of capillaries. It can be seen that the capillary pressure for water phase decreases with the increase of saturation in unsaturated porous rocks. It is found that the capillary pressure for water phase decreases as the tortuosity Fractal dimension decreases. It is further seen that the capillary pressure for water phase increases with the decrease of porosity, and at low porosity, the capillary pressure increases sharply with the decrease of porosity. Besides, it can be observed that the water relative permeability increases with the increase of saturation in unsaturated porous rocks. This predicted t...
E M A Perrier - One of the best experts on this subject based on the ideXlab platform.
-
the pore solid Fractal Model of soil density scaling
European Journal of Soil Science, 2003Co-Authors: N R A Bird, E M A PerrierAbstract:Summary We have developed the Fractal approach to Modelling variations in soil bulk density and porosity with scale of measurement or sample size. A new expression is derived for each quantity based on the pore–solid Fractal (PSF) Model of soil structure. This new general expression covers a range of Fractal media and accommodates existing Fractal Models as special cases. Model outputs cover a range of scaling behaviour expressed in terms of monotonic functions, from increasing density and decreasing porosity, through constant porosity and density to decreasing density and increasing porosity with increasing scale of measurement. We demonstrate the link between this new Model for the scaling of porosity and bulk density and the water retention Model for the PSF. The Model for scaling bulk density is fitted to data on aggregate bulk density and shown to yield good fits describing bulk density decreasing with increasing aggregate size. Porosity scaling is also inferred from the fitting of water retention data. Inferred porosities from different fittings are shown to follow decreasing, scale-invariant and increasing values with decreasing size of structural unit, and these theoretical results emphasize the need for further experimental investigation on the basic issue of density scaling in soil science.
Guanhua Huang - One of the best experts on this subject based on the ideXlab platform.
-
evaluation of soil water retention curve with the pore solid Fractal Model
Geoderma, 2005Co-Authors: Guanhua Huang, Renduo ZhangAbstract:Abstract Empirical Models have been developed to describe the soil water retention curve (SWRC). Applications of the Fractal theory may provide a useful tool to fill the gap between the use of empirical Models and physical interpretation of their parameters. Especially a more generalized Model for the SWRC has been developed based on the pore–solid Fractal (PSF) distribution. The PSF Model covers several existing Models as its special cases and theoretically provides a direct way to estimate the SWRC Fractal dimension from particle size distributions (PSDs). The first objective of this study was to evaluate the SWRC with the PSF distribution using more than 400 data sets of PSD and SWRC. The second objective was to establish a relationship between the Fractal dimension and soil texture. Analyses of the data sets showed that the Fractal dimension values estimated using the PSD data were consistently smaller than those estimated using the SWRC data. Therefore, using the Fractal dimension from PSD to predict the SWRC will result in underestimation. To resolve the problem, the soil data sets of PSD and SWRC were used to establish relationships between the Fractal dimensions in the PSF Model of SWRC and soil clay content as well as soil texture class. Independent SWRC data sets were used to test the methods. Predicted results using the PSF Model of SWRC with the Fractal dimension estimated using clay content or soil texture class were compared with the measured soil water retention data. Linear regressions of the predicted and measured SWRC showed good agreement for relatively fine texture soils with the coefficients of determination (r2) of 0.940.
