Weak discontinuity in porous media: an enriched EFG method for fully coupled layered porous media

In this paper, a series of multimaterial benchmark problems in saturated and partially saturated two‐phase and three‐phase deforming porous media are addressed. To solve the process of fluid flow in partially saturated porous media, a fully coupled three‐phase formulation is developed on the basis of available experimental relations for updating saturation and permeabilities during the analysis. The well‐known element free Galerkin mesh‐free method is adopted. The partition of unity property of MLS shape functions allows for the field variables to be extrinsically enriched by appropriate functions that introduce existing discontinuities in the solution field. Enrichment of the main unknowns including solid displacement, water phase pressure, and gas phase pressure are accounted for, and a suitable enrichment strategy for different discontinuity types are discussed. In the case of weak discontinuity, the enrichment technique previously used by Krongauz and Belytschko [Int. J. Numer. Meth. Engng., 1998; 41:1215–1233] is selected. As these functions possess discontinuity in their first derivatives, they can be used for modeling material interfaces, generating only minor oscillations in derivative fields (strain and pressure gradients for multiphase porous media), as opposed to unenriched and constrained mesh‐free methods. Different problems of multimaterial poro‐elasticity including fully saturated, partially saturated one, and two‐phase flows under the assumption of fully coupled extended formulation of Biot are examined. As a further development, problems involved with both material interface and impermeable discontinuities, where no fluid exchange is permitted across the discontinuity, are considered and numerically discussed. Copyright © 2014 John Wiley & Sons, Ltd.     

Mollusks from the lower quaternary Chauda sediments of the Black Sea

The analysis of paleontological remains in many samples from the Lower Quaternary Chauda sediments drilled and cored on the Bulgarian shelf of the Black Sea revealed widespread mollusks of the genera Didacna and Dreissena (Didacna tschaudae guriana, D. tschaudae, D. pleistopleura, D. crassa guriensis, Dreissena rostriformis tschaudae, D. rostriformis abchasica) accompanied by reworked Neogene representatives of the genus Digressodacna. In numerous places of a continental slope and an adjacent deep-sea depressions near Crimea and Caucasus the similar mollusc assemblage is described in the redeposited state for the first time. The composition of palynological spectra and diatom assemblages in shelf sediments indicates climate changes during the Chaudan period. The Chaudan mollusk fauna from the Black Sea sediments, which is lacking Caspian Bakuan species characteristic of the Chauda stratotype, is compositionally close to the mollusk assemblage from basal layers of the Chauda Horizon in the Guriya area of Georgia (“Gurian” Chauda). These data imply repeated changes in the level of the Chaudan basin between present-day isobaths of −30...−50 to −140 m.     

Post-2012 CDM multi-criteria analysis of industries in six Asian countries: Iranian case study

The prospects of the Clean Development Mechanism (CDM) and for carbon income, up to and beyond 2012, in the industrial sectors of Iran and five other Asian countries are investigated. The attractiveness and suitability of each host country, the status of their industrial sectors (based on four post-2012 scenarios), and the post-2012 potential of the CDM (or similar carbon projects) in these sectors are all examined. A multi-criteria analysis of Iran, Saudi Arabia, the UAE, Qatar, China, and India, based on seven sets of criteria (institutional, regulatory, economic, political, social, CDM experience, and energy production/consumption), is conducted, and the post-2012 potential carbon incomes of each country – based on CO₂e emissions of industrial processes – are calculated. Finally, the Iranian industrial sector and the impact of deregulation of energy prices are examined. The post-2012 potential savings in the Iranian industrial sector are calculated based on energy savings, carbon income, and environmental savings. The results indicate that there is strong demand for investment and new technology in this sector to combat several-fold energy price increases. Moreover, high-priced carbon credits could play a meaningful role in post-2012 energy policies in this sector.

Policy relevance

This research is the first study to quantify the carbon market potentials in the industrial sectors of the selected Organization of the Petroleum Exporting Countries (OPEC) members. The Kyoto Protocol is considered by most OPEC countries to be a mixed bag of threats and opportunities and they have shown ambivalence towards it, mainly due to the threat a reduction of fossil fuel consumption poses to their economies. On the other hand, energy efficiency is a desirable goal for their industrial sectors. Iran, as an OPEC member country with vast energy resources, has mostly ignored the CDM during the first commitment period of the Kyoto Protocol and has performed poorly on CDM implementation. However, the current deregulation of energy prices in Iran, with profound cuts in energy subsidies, would definitely alter the perspective of its industrial decision makers on the post-2012 carbon potentials.     

A hydrochemical and dye- tracing investigation in the Posht-e-Naz Karstic Aquifer, Alburz Mountain, Northern Iran

A hydrochemical and tracer study (uranine injection) was conducted in Jurassic limestone of the Posht-e-Naz area in the Alborz belt to evaluate hydraulic relations between a large diameter (about 100 m) sinkhole and springs and aquifer parameters. A main goal of the project was to find out the source of turbidity of the Emarate drinking water supply spring (SP4) in rainy season. Springs discharge were measured and hydrochemical investigation were carried out. The uranine tracer was injected and eight springs, three wells and the Neka River were selected and totally 989 samples in 107 days were collected. Hydrochemical data demonstrated a relative connection between sinkhole (Sh1) and spring (SP4). The results of the tracing by sampling water indicated only a hydraulic connection between Sange- Nou spring (SP8) and injection point, while the charcoal packets analysis revealed tracer exits from spring numbers SP1, SP3, SP4, SP5, SP8, in wells W1 and W2, and in the Neka River. The concentration — time curves of charcoal packets for qualitative analysis and exit tracer for quantitative analysis is also assessed.     

Numerical investigation of hydraulic characteristics and prediction of cavitation number in Shahid Madani Dam's Spillway

The prediction of the probability of cavitation occurrence to prevent serious damages in the spillways is the major concern for hydraulic engineers. In this research, the three-dimensional model of Shahid Madani Dam’s spillway was simulated with the Flow 3D software and by the comparison of numerical model results with the experi-mental data, the probability of occurrence of the cavitation phenomenon has been investigated. The flow parameters including pressure, velocity, and water depth were calculated for three different flow rates of 495 m3/s, 705 m3/s and 2 205 m3/s respectively. The Renormalization Group (RNG) turbulence model was used to simulate current turbulence. Comparison of simulation results for pressure, velocity and water depth with the results of the experimental model with two statistical indices Root Mean Square Error (RMSE) and Coefficient of Determination (R2) showed that the numerical simulation results are in good consistency with experimental model. However, simulation results indicated that at any flow rates with a return period of 1 000 years, probable maximum flood and designed flow rates, the cavitation number is not lower than the critical cavitation number; Therefore, it is predicted that the cavitation phenomenon in Shahid Madani Dam’s spillway will not happen.     

Control of Cambrian evaporites on fracturing in fault-related anticlines in the Zagros fold-and-thrust belt

Orientation and distribution of fractures in the Oligocene–Early Miocene Asmari Formation (a major reservoir rock of the Zagros petroleum system) were investigated in two anticlines of the Zagros fold-and-thrust belt. The Sim and Kuh-e-Asmari anticlines developed in the areas of the Zagros characterized by the occurrence and absence of Cambrian evaporites at the bottom of the stratigraphic pile, respectively. The aim was to outline major differences in terms of fracture spacing and saturation. Organic matter maturity and clay minerals-based geothermometers suggest that the depth of deformation for the top of the Asmari Formation in the Kuh-e-Asmari anticline was in the range of 1.5–2.7 km assuming a geothermal gradient of 22.5 °C/km. The Asmari Formation in the Sim anticline probably experienced a slightly deeper sedimentary burial (maximum 3 km) with a geothermal gradient of 20 °C/km. The spacing of fractures is generally 2–3 times larger (i.e., strain accommodated by fracturing is smaller) in the Sim anticline than in the Kuh-e-Asmari anticline. This is consistent with regional geological studies, analogue, and numerical models that suggest that thrust faults geometry and related folds are markedly different in the absence or presence of a weak decòllement (evaporites). The larger spacing in the Sim anticline is also consistent with higher temperature predicted for the Asmari Formation in this area. By contrast, the orientation of fractures with respect to the fold axes is the same in both anticlines. The fracture systems are rather immature in both anticlines. The amount and density of fractures in the twofolds are controlled by regional (occurrence/absence of salt and probably different burial), rather than local features (fold geometry).     

A study of the behaviour of brittle rocks subjected to confined stress based on the Mohr–Coulomb failure criterion

In this study the relationship between brittle rocks’ behaviour and uniaxial compression stress is obtained based on the Mohr-Coulomb failure criterion and the behavioural characteristics of brittle rocks under uniaxial compression stress are investigated. According to the laboratory uniaxial compression tests on granite rocks, and also available results in the literature, required parameters in the study are obtained. It is indicated that the behaviour of brittle rocks which is affected by uniaxial compression is function of cohesion. In the other words, cohesion changes as the uniaxial compression increases. Also, in yield point where its stress is equivalent to the uniaxial compressive strength, the cohesion maximises. By suggesting a new viewpoint to the Mohr’s circle, normal stresses on failure plane, shear stresses tangential to the failure plane and hydrostatic stresses are investigated. Results show that, normal stress on the failure plane in yield point of the behavioural curve equals zero and shear stress tangential to the failure plane is maximum which is equal to the maximum rocks’ natural strength. Also, in this point the strength is equi-pressure, therefore the stress is of hydrostatic type.     

Statistical approach to inverse distance interpolation

Inverse distance interpolation is a robust and widely used estimation technique. Variants of kriging are often proposed as statistical techniques with superior mathematical properties such as minimum error variance; however, the robustness and simplicity of inverse distance interpolation motivate its continued use. This paper presents an approach to integrate statistical controls such as minimum error variance into inverse distance interpolation. The optimal exponent and number of data may be calculated globally or locally. Measures of uncertainty and local smoothness may be derived from inverse distance estimates.