Effects of the geometry of two‐dimensional fractures on their hydraulic aperture and on the validity of the local cubic law          下载免费PDF全文

Ahmad Hajjar  Luc Scholtès  Constantin Oltéan  Michel Antoine Buès 《水文研究》2018,32(16):2510-2525

Flow through rough fractures is investigated numerically in order to assess the validity of the local cubic law for different fracture geometries. Two‐dimensional channels with sinusoidal walls having different geometrical properties defined by the aperture, the amplitude, and the wavelength of the walls' corrugations, the corrugations asymmetry, and the phase shift between the two walls are considered to represent different fracture geometries. First, it is analytically shown that the hydraulic aperture clearly deviates from the mean aperture when the walls' roughness, the phase shift, and/or the asymmetry between the fracture walls are relatively high. The continuity and the Navier–Stokes equations are then solved by means of the finite element method and the numerical solutions compared to the theoretical predictions of the local cubic law. Reynolds numbers ranging from 0.066 to 66.66 are investigated so as to focus more particularly on the effect of flow inertial effects on the validity of the local cubic law. For low Reynolds number, typically less than 15, the local cubic law properly describes the fracture flow, especially when the fracture walls have small corrugation amplitudes. For Reynolds numbers higher than 15, the local cubic law is valid under the conditions that the fracture presents a low aspect ratio, small corrugation amplitudes, and a moderate phase lag between its walls.  相似文献   

REE geochemistry of core sediments of Cauvery delta,India for provenance studies     

Ahmad  Malik Zubair  Singh  Pramod 《中国地球化学学报》2020,39(4):512-526

Acta Geochimica - The rare earth element (REE) geochemical composition of sediments from two cores were used to investigate the provenances of the Late Pleistocene to Holocene sediments of Cauvery...  相似文献   

Prediction of copper content in waste dump of Sarcheshmeh copper mine using visible and near-infrared reflectance spectroscopy     

Khosravi  Vahid  Ardejani  Faramarz Doulati  Aryafar  Ahmad  Yousefi  Saeed  Karami  Shawgar 《Environmental Earth Sciences》2020,79(7):1-16

The pore structure characteristics of soil are closely related to soil engineering properties. For saline soil distributed in seasonally frozen areas, existing studies have focused on the influence of freeze–thaw cycles on pore structure, while the influence of soluble salt in the soil is not well understood. This study aims to explore the influence of salt content and salt type on the pore structure of freeze-thawed soil. Soil samples with different salt contents (0–2%) and types (bicarbonate salt and sulfate salt) were subjected to 10 freeze–thaw tests, and their pore size distributions (PSDs) were obtained by mercury intrusion porosimetry tests. In addition, the PSDs were quantitatively analyzed by fractal theory. For both salts, the PSDs of the tested soil samples were bimodal after the freeze–thaw cycles, and the porosity of saline soil samples increased with increasing salt content overall. However, the contents of various types of pores in soil samples with two salt types were quite different. The variation in bicarbonate salt content mainly affected the mesopore and macropore contents in the soil samples, and their change trends were opposite to each other. For soil samples with sulfate salt, the porosity and macropore content increased significantly when the salt content exceeded 1%. In addition, the pore structures in saline soil presented fractal characteristics after the freeze–thaw cycles, and the fractal dimension was positively correlated with macropore content. This study may provide references for understanding the engineering properties of saline soil in seasonally frozen areas at the microscale.  相似文献   

Heavy metal pollution and human health risk assessment for exposure to surface soil of mining area: a comprehensive study     

Abouian Jahromi  Mohammad  Jamshidi-Zanjani  Ahmad  Khodadadi Darban  Ahmad 《Environmental Earth Sciences》2020,79(14):1-11

Climate change projections indicate an increase in intense rainfall events with consequent river flooding, which could lead to devastating natural disaster  相似文献   

Geochemical Prospectivity Mapping Through a Feature Extraction–Selection Classification Scheme     

Zekri  Hamid  Cohen  David R.  Mokhtari  Ahmad Reza  Esmaeili  Abbas 《Natural Resources Research》2019,28(3):849-865

Natural Resources Research - Machine learning (ML) schemes can enhance success in geochemical prospectivity mapping. This study has examined the effectiveness of several feature extraction or...  相似文献   

Socio-political and ecological stresses on traditional pastoral systems: A review     

Muhammad  Khurshid  Mohammad  Nafees  Abdullah  Khan  Mehmet  Somuncu  Ashfaq  Ahmad Khan  Wajid  Rashid 《地理学报(英文版)》2019,29(10):1758-1770

Journal of Geographical Sciences - Pastoralism is a viable socio-economic system-shaped by landless and agro-pastoral communities in many pastoral regions of the world. This system is mainly based...  相似文献   

Flood risk perception and its determinants among rural households in two communities in Khyber Pakhtunkhwa,Pakistan     

Ullah  Farman  Saqib  Shahab E.  Ahmad  Mokbul Morshed  Fadlallah  Mahmoud Ali 《Natural Hazards》2020,104(1):225-247

Natural Hazards - Risk perception plays a vital part in flood risk management and mitigation strategies. Therefore, this study aims at first to measure the risk perception of the vulnerable...  相似文献   

Gravitational clustering of galaxies: Derivation of two-point galaxy correlation function using statistical mechanics of cosmological many-body problem     

Farooq Ahmad  Manzoor A. Malik  M. Maqbool Bhat 《Astrophysics and Space Science》2016,361(7):223

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Investigation of Failed Slopes Based on a New Method of Back Analysis in Rock Masses: A Case Study     

Taherynia  Mohammad Hossein  Koopialipoor  Mohammadreza  Azizzadeh  Abbas  Fahimifar  Ahmad  Ghyasvand  Soheil 《Geotechnical and Geological Engineering》2021,39(7):5119-5133

Geotechnical and Geological Engineering - Small variation in shear strength parameters results in remarkable changes in the safety factor (SF) of a rock slope. In this regard, rock mass strength of...  相似文献   

New chelating resin for preconcentration and determination of molybdenum by inductive couple plasma atomic emission spectroscopy     

H. Sid Kalal Ph.D.  H. Ahmad Panahi Ph.D.  N. Framarzi  E. Moniri Ph.D.  A. Naeemy  H. Hoveidi Ph.D.  A. Abhari 《International Journal of Environmental Science and Technology》2011,8(3):501-512

A chelating resin is prepared by condensation polymerization of aniline with formaldehyde and characterized by Fourier transform infrared spectrometer, elemental analysis and thermogravimetric analysis and studied for the preconcentration and determination of trace Molybdate ion from environmental water sample using inductive couple plasma atomic emission spectroscopy. The optimum pH value for sorption of the metal ion was 5. The sorption capacity of functionalized resin is 3.1 mg/g. The chelating sorbent can be reused for 20 cycles of sorption-desorption without any significant change in sorption capacity. The best desorption of the metal ions from resin was obtained by 0.5 mol/L nitric acid as eluting agent. The profile of molybdenum uptake on this sorbent reflects good accessibility of the chelating sites in the aniline-formaldehyde. Scatchard analysis revealed that the homogeneous binding sites were formed in the polymers. The equilibrium adsorption data of Molybdate ion modified resin were analyzed by five isotherm models such as Langmuir, Freundlich and Temkin. Langmuir isotherm parameters obtained from the four Langmuir linear equations by using linear method. Based on the Langmuir isotherm analysis, the monolayer adsorption capacity was determined to be 4.03 mg/g at 20 °C. The method was applied for molybdenum ions determination from river water sample.  相似文献