Porosity Range Research Articles

Prediction of both diffusive and hydraulic conductance in the pore network model extracted from 3D images using deep learning

Abstract Pore network modeling (PNM) with network extracted from 3D images is widely used for studying mass transport in porous media, with its accuracy heavily dependent on the precise determination of hydraulic and diffusive conductance values of local pore pairs. Deep learning (DL) prediction based on true pore geometry offers a promising approach for conductance estimation. However, due to arbitrarily orientation and the lack of explicit inlet and outlet surfaces in 3D extracted pore pair geometries, existing studies [24,25] have relied only on 2D cross section images for hydraulic conductance prediction. A custom finite difference method was recently developed, capable exclusively of estimating diffusion conductance from 3D pore geometry [26]. In this work, a convolutional neural network (CNN) was trained to estimate both diffusive and hydraulic conductance values, with reference ground truth values obtained by applying the Lattice Boltzmann Method (LBM) on 3D pore pair geometries. The predicted pore pair conductance values from the CNN closely matched the LBM results on unseen segmented image data. This study highlights the importance of using the full 3D pore pair geometry for accurate hydraulic conductance evaluation, rather than relying solely on 2D throat cross sections. To evaluate the generality of our method, we calculated the permeability and diffusivity of 3D porous media across a wide range of porosities using PNM with local conductance values predicted by our DL model. Comparisons with results of LBM indicate that while diffusivity was accurately predicted, permeability was underestimated. This underestimation is attributed to the over-segmentation of pore spaces, which resulted in an underestimated flow rate.

Porosity effect on the thermal conductivity of sintered powder materials

In this work, the effective thermal conductivity of sintered powder materials is studied. The extensive literature related to the proposed models about this property in all kind of porous materials is reviewed, and a new equation is proposed as a function of the fully dense material conductivity, the porosity of the material and the tap porosity of the starting powder. This equation covers the porosity range of powder aggregates from the tap porosity to zero porosity, and also applies to sintered powders. The proposed equation has been experimentally validated by fitting to experimental data of metallic sintered powder materials measured at room temperature, resulting very good agreements. Also, alternative models proposed by other authors have been fitted to the same experimental data to check the relative goodness of the proposed model. The results allow to conclude that a percolation model can describe the behaviour of the effective thermal conductivity of sintered powder materials with low and medium porosity levels.

From Waste to Worth: Innovative Pyrolysis of Textile Waste into Microporous Carbons for Enhanced Environmental Sustainability

The generation of synthetic textile waste is a growing global concern, with an unsustainable rate of expansion. This study addresses the growing issue of synthetic textile waste by converting polyester–polyurethane (PET-PU) post-industrial scraps into microporous carbon materials, which can be utilized for wastewater treatment. Using a straightforward pyrolysis process, we achieved a high specific surface area (632 m2/g) and narrow porosity range (2–10 Å) without requiring chemical activation. The produced carbon materials effectively adsorbed methylene blue and orange II dyes, with maximum adsorption capacities of 169.49 mg/g and 147.56 mg/g, respectively. Kinetic studies demonstrated that adsorption followed a pseudo-second-order model, indicating strong interactions between the adsorbent and dyes. Regeneration tests showed that the C-PET-PU could be reused for multiple cycles with over 85% retention of its original adsorption capacity. Preliminary life cycle assessment (LCA) and life cycle cost (LCC) analysis highlighted the environmental and economic advantages of this upcycling approach, showing a reduced global warming potential and a production cost of approximately 1.65 EUR/kg. These findings suggest that transforming PET-PU waste into valuable adsorbents provides a sustainable solution for the circular economy and highlights the potential for broader applications in environmental remediation.

Comprehensive Study of Sub-micron Porous Titanium-zirconium Scaffolds Fabricated by Liquid Metal Dealloying

This article investigates the microstructure, mechanical properties and biocompatibility of ultrafine porous titanium-zirconium (TiZr) alloys synthesized by the liquid metal dealloying (LMD) at a temperature of 1023K for various immersion times. The dealloying of Ti20Zr20Cu60 precursors in molten magnesium causes to self-organize three-dimensional hcp-α structures by surface diffusion mechanism, wherein the ligament size, density and porosity range from 130 to 280nm, 2.8 to 3.2g/cm3 and 0.43 to 0.5, respectively. The compression test results of porous products indicate a perfect combination of high compressive strength (415−620MPa) and low elastic modulus (2.1−3.2GPa) matching that of the human bone. The maximum ligament size (280nm), density (3.2g/cm3) and compressive strength (620MPa) corresponds to immersion time of 600s; thereby, the mechanical characteristics can be tailored by modifying the process parameters. Meanwhile, the elastic modulus and compressive strength enhance almost linearly with increasing the relative density in accordance with the Gibson and Ashby model. The in-vitro experiments with MG-63 osteoblast cells also suggests the immersion time of 600s to better support the bone tissue ingrowth. The porous TiZr alloy fabricated by the new dealloying method can be considered as a novel biomaterial for dental implants owing to its unique microstructure, compressive features and biocompatibility.

The in-depth analysis and validation of momentum dispersion modeling based on direct numerical simulation

Based on the pore scale prevalence hypothesis (PSPH) in porous media flows, the PSPH model accounts for the effects of momentum dispersion and has been preliminary validated and applied by Rao and Jin [Possibility for survival of macroscopic turbulence in porous media with high porosity, J. Fluid Mech. 937, A17 (2022)]. This paper conducts further in-depth analysis of the PSPH model and validates it across various geometries of homogeneous porous media based on direct numerical simulation (DNS). A detailed analysis of DNS results indicates that the Darcy and Forchheimer terms dominate the flow field with low and high Reynolds numbers, respectively. The Darcy–Forchheimer term effectively approximates the total drag, which consists of both pressure drag and viscous drag throughout the flow field. The contribution of the momentum dispersion term is significant only within the first representative elementary volume adjacent to the boundary, especially at high Reynolds numbers. These findings verify the necessity of Reynolds number-dependent effective viscosity in the PSPH model. Results of the PSPH model are compared with DNS results for isotropic and anisotropic porous media across various geometries. The remarkable consistency between the PSPH model and DNS across a wide range of Reynolds numbers and porosities strongly indicates the potential power of the PSPH model in related industrial applications.

Optimized the stress shielding reduction of different lattice structures in cervical spine implants using FEA and VIKOR fuzzy MCDM analysis

The difference in material properties between bone and implants might cause the bone surrounding the implant to weaken as a result of stress shielding, which prevents the required stress for bone remodeling. Integrating lattice structures into implants is an effective method to reduce the negative effects of stress shielding. This study investigates the characteristics of three lattice structures (Diamond, Gyroid, and Primitive) with different levels of porosity ranging from 25% to 95%. The lattice structures are standardized for representation, and finite element analysis is performed on the C5–C6 segment of the cervical spine using the implant model. The VIKOR Fuzzy Multi Decision Making technique is used to maximize stress levels in the interbody fusion cage and identify the best appropriate lattice structure. The findings suggest that Diamond and Gyroid structures exhibit superior performance compared to the Primitive lattice, with an ideal porosity range of 5% for cage implants.

Source-rock and petrophysical evaluation of the Late Cretaceous Haymana Formation, Haymana Basin, Central Anatolia, Turkey

This study investigates the petroleum potential of mudstones of the Late Cretaceous Haymana Formation in the Haymana Basin, Turkey. The lithofacies, pore structure and source-rock characteristics of the mudstones are examined using stratigraphic, sedimentological, petrophysical and organic geochemical methods along four stratigraphic sections and other sampling sites. The depositional model presents a facies distribution within a submarine fan system. According to the bulk mineralogy, the identified lithofacies are mixed mudstone, mixed siliceous mudstone, marl, mixed carbonate mudstone, argillaceous/siliceous mudstone and clay-rich siliceous mudstone. XRD and mercury intrusion measurements suggest that the macropores (>50 nm) of the mudstones formed by dissolution of calcite, while mesopores (2–50 nm) developed around the clay–quartz/feldspar. Of the analysed samples, no lithofacies class is distinct with any specific range of porosity or permeability, which suggests a strong heterogeneity in pore throat size, mineral content and grain size. The black shale from the NW of the basin with a total organic carbon (TOC) content of 1.19%, S1 value of 0.07 mg g −1 , S2 value of 1.01 mg g −1 and a T max value of 441°C is a relatively more mature source rock, although it still exhibits a poor petroleum potential. Overall, the TOC values (average of 0.38%) of the mudstones suggest organic-poor rock characteristics for the Haymana Formation in the studied parts of the Haymana Basin.

Improving the Battery Metrics of Commercial Hard Carbon through S-Doping for Sodium-Ion Batteries

Hard carbon (HC) is now the leading choice for the anode in Sodium-ion Batteries (SIBs) because of its low operating voltage, high reversible capacity, and the wide range of inexpensive materials that may be used to synthesize it. The primary concern in commercial HCs is the initial Coulombic efficiency (ICE) and rate capability [1-2]. Hard carbon (HC) can exhibit a wide range of microstructures, morphologies, surface areas (including different types of pores), and porosities. These characteristics are determined by the carbon-rich material employed during synthesis and significantly impact the methods by which sodium ions are stored in HCs [3]. This study presents a novel structure of S-doped hard carbon derived from commercial HC. The sulfur-doped hard carbon material exhibits 67% ICE and maintains 94% of its capacity after undergoing 500 cycles at a rate of 300 mA/g (Fig.1). The sodium-ion storage mechanism of the S-doped HC material is analyzed using ex-situ Raman, XRD, SEM, EPR, and XPS techniques. These post-treated HC are compared with available commercial HC as anodes in sodium-ion batteries (SIBs) for a state-of-the-art evaluation of the battery metrics.

Turbulent Flow and Wall Forces in Staggered Square Cylinder Porous Media: An Large Eddy Simulation Analysis

Abstract The wall-modeled-large eddy simulation (WMLES) technique was used to analyze turbulent flow in a porous medium composed of a staggered arrangement of square cylinders. The study focused on a porosity range of 0.3–0.8 at a pore Reynolds number of 104. The research provides novel information on pressure and shear force distributions around the cylinders and time-averaged values of particle drag and fluctuating lift coefficients. Results indicate that flow physics are mainly driven by an expansion region in front of the central particle and another one in the rear, where the flow is contracted and strongly accelerated. In the first region, velocities, turbulence kinetic energy (k), and its dissipation rate (ε) are attenuated by a sudden pressure increase, while in the contraction region, the effect is the opposite. As porosity decreases, flow gradients and the overall levels of k, ε, and normalized Reynolds stresses become more significant. Turbulent anisotropy increases as porosity decreases below 0.6. Hydrodynamic stresses in the last interval present relatively uniform levels, which is a unique feature that may be considered in designing dedicated engineering devices with controlled stresses.

Fabrication of Mesoporous SiO<sub>2</sub> Shells for Dye Adsorption Studies

The present work focuses on the fabrication of novel hybrid materials for toxic dye removal from an aqueous environment. Nanocarbon template (20-30 nm) was coated with tri-ethyl-orthosilicate (TEOS). The core-shell structure developed was further air pyrolyzed at 600 °C to produce mesoporous silica shells. The pore structures and characteristics of the material were evaluated using XRD, nitrogen adsorption studies, SEM, and TEM. Owing to the hierarchical porosity in range of 1-4 nm and 10-20 nm their adsorption studies were investigated for Phenol-Red. Dye adsorption studies performed revealed 98% removal efficiency with only 20 mg of adsorbent dose within 15 minutes.

Development of nanoporous carbon models with tunable pore structures via the random packing-virtual atom method

Nanoporous carbon (NPC) is widely utilized due to its highly developed pore structure. The complex structure-property relationships of NPC necessitate simulation methods to complement experimental approaches, with structural model construction serving as the foundation. Regulating pore structures during construction of NPC models poses a significant challenge, and existing strategies for introducing pores have inherent limitations. In this work, NPC models were constructed using the random packing method, incorporating virtual atoms (VAs) to regulate pore development, achieving targeted control over the pore structure. The results indicate that the system density is a critical factor in determining the porosity range of NPC models, whereas VAs provide an effective means to regulate pore characteristics. By adjusting the number and radius of VAs, the pore characteristics of the models can be tuned, although their effects on different features vary. The number of VAs significantly influences SSA, which increases with the number of VAs, whereas VA radius predominantly affects porosity, increasing as the radius expands. Furthermore, the NPC-SDG-AC model was developed with an SSA of 968 m2/g and a pore size distribution consistent with actual microporous distribution. NPC-1, NPC-2, and NPC-3 models were also constructed, exhibiting mesoporous, large microporous, and small microporous characteristics.

Scaling Laws at Stall in an Axial Compressor with an Upstream Perturbation

An experimental campaign has been conducted to assess the effect of total pressure inlet distortion on a single stage axial compressor. Different grid sectors have been installed in front of the inlet of the compressor to generate the distortion. Pressure measurements and particle image velocimetry have been used to characterize the impact of the distortion on the flowfield and the performance of the compressor. The broad range of porosity and angular extension of the grid sectors has allowed identifying four different flow regimes characterised by a different response of the compressor. In particular, the low porosity introduces flow regimes which have been never encountered in typical distortion tests restricted to high-porosity grids. In two of these regimes, it has been possible to identify a new scaling of the stall margin versus a new distortion index based on more solid physical ground than already existing indices such as the DC60. The experiments have also shown that for each of these four flow regimes behind the grid different rotating stall features (spike stall or modal stall) appear. A scaling of the stall dynamic has been finally provided thanks to analysis of unsteady casing static pressure signals acquired during the stall transient.

Quantitative Evaluation of Deformation in High-Speed Magnetic Flux Leakage Signals for Weld Defects in Oil and Gas Pipelines

Complex multiphase flow in oil and gas pipelines raises safety risks. Magnetic flux leakage (MFL) detection effectively identifies pipeline defects. However, the high-speed movement of MFL inspection tools induces motion-induced eddy currents (MIECs), complicating defect recognition and quantification. Most prior research has primarily focused on rectangular defects, leaving a gap in understanding the impact of MIECs on weld defects. This paper proposes the amplitude and shape deformation coefficients to analyze the influence of velocity on various weld defects, including internal reinforcement, lack of penetration, crack, external corrosion, internal corrosion, porosity, and lack of fusion. Utilizing these coefficients, this study examines the influence of the defect size and magnetizer configuration on these velocity-induced effects. The results show that the shape deformation coefficients range from 2.75 to 3.57 for Bx and from −0.13 to −0.3 for By, indicating a significant change in the MFL signal shape at 10 m/s compared to 0 m/s. The amplitude deformation coefficients for lack of penetration, internal corrosion, and porosity range from −0.01 to 0.1 for Bx, and from 0.86 to 0.98 for By, suggesting a decrease in peak-to-peak values. In contrast, other defects exhibit an increase in peak-to-peak values, indicating that the velocity effect may enhance the MFL signal. Also, the defect size and magnetizer configuration can affect the velocity effect on signals. These findings provide essential guidance for quantifying defect sizes and a solid foundation for designing more effective magnetization devices.

Microvoiding and constitutive damage modeling with artificial neural networks

Continuum models of porous media have revolutionized computational fracture mechanics for traditional ductile materials, but the inherent assumptions have limited generalizability to other target materials or loading conditions. Here, we adopt a series of artificial neural networks (ANNs) to predict both the microscopic voiding characteristics (void shape, porosity) and macroscopic stress–strain constitutive response of porous elasto-plastic materials under various deformation states. We train the ANNs on a dataset generated from finite element models of 3D representative volume elements (RVEs), each containing a discrete spherical void, subjected to combinations of loading states. Results show that the data-driven model is capable of interpolative predictions as well as some levels of extrapolative predictions across a wide range of initial porosities (0–20%) and loading states outside of the training dataset, even at high deformation strains which induce extensive material softening and void growth. Through transfer learning, we further demonstrate that the ANNs, originally trained on a specific porous material dataset, can be readily adapted to other porous materials with substantially different properties through a significantly reduced training dataset. We discuss the implications of this machine learning approach vis-à-vis the extensively-developed Gurson model for porous material damage and failure predictions.

Statistical Analysis of Core Porosity of Benin’s Offshore Coastal Sedimentary Basin Reservoir Formations

The reservoir formation porosity is one of the main reservoirs petrophysical properties required for fields characterization. The study aims to verify whether the core porosity of Benin’s offshore petroleum block 1 reservoir formations depends significantly upon the nature of reservoir formations and to determine the porosity ranges, the average porosities and the porosity percentiles (P10, P50 and P90) of these formations. The results have shown that Benin’s Petroleum block 1 reservoir formations core porosities depend significantly on the horizons and the nature of formations. Moreover, the core porosities range from 2.1 to 27.8 percent with averages between 12.31 and 18.95 percent. H9 Albian sand has the highest porosity and H8 Albian sand the lowest one. Abeokuta reservoir formations porosities are respectively 16.95 and 17.77 percent for H6 and H6.5 horizons. They have 50 and 90 percent of chance to be respectively greater than 12 and 5.84 percent no matter the formation. Abeokuta formation core porosity has high chance to be more than 17.3 percent.

Optimizing the Pore Structure of Lotus-Type Porous Copper Fabricated by Continuous Casting.

Lotus-type porous copper was fabricated using a continuous casting method in pressurized hydrogen and nitrogen gas atmospheres. This study evaluates the effects of process parameters, such as the hydrogen ratio, total pressure, and transference velocity, on the resulting pore structure. A continuous casting process was developed to facilitate the mass production of lotus-type porous copper. To achieve the desired porosity and pore diameter for large-scale manufacturing, a systematic evaluation of the influence of each process parameter was conducted. Lotus-type porous copper was produced within a hydrogen ratio range of 25-50%, a transference velocity range of 30-90 mm∙min-1, and a total pressure range of 0.2-0.4 MPa. As a result, the porosity ranged from 36% to 55% and the pore size varied from 300 to 1500 µm, demonstrating a wide range of porosities and pore sizes. Through process optimization, it is possible to control the porosity and pore size. The hydrogen ratio and total pressure were found to primarily affect porosity, whereas the hydrogen ratio, transference velocity, and total pressure significantly influenced pore diameter. When considering these parameters together, porosity was most influenced by the hydrogen ratio, whereas the total pressure and transference velocity had a greater influence on pore diameter. Reducing the hydrogen ratio and increasing the transference velocity and total pressure reduced the pore diameter and porosity. This optimization of the continuous casting process enables the control of porosity and pore diameter, facilitating the production of lotus-type porous copper with the desired pore structures.

Effect of Bio-Herbicide Application on Durum Wheat Quality: From Grain to Bread Passing through Wholemeal Flour

Using plant extracts to replace traditional chemical herbicides plays an essential role in sustainable agriculture. The present work evaluated the quality of durum wheat cv Valbelice in two years (2014 and 2016) using plant aqueous extracts of sumac (Rhus coriaria L.) and mugwort (Artemisia arborescens L.) as bio-herbicides on the main quality characteristics of durum wheat. The untreated, water-treated, and chemically treated durum wheat products were also analyzed as controls. Following the official methodologies, grain commercial analyses and defects of the kernels were determined. The main chemical and technological features were determined on the wholemeal flour: proteins, dry matter, dry gluten, gluten index, colorimetric parameters, mixograph, falling number, and sedimentation test in SDS. An experimental bread-making test was performed, and the main parameters were detected on the breads: bread volume, weight, moisture, porosity, hardness, and colorimetric parameters on crumb and crust. Within the two years, grain commercial analyses of the total five treatments showed no statistically significant differences concerning test weight (range 75.47–84.33 kg/hL) and thousand kernel weight (range 26.58–35.36 kg/hL). Differently, significant differences were observed in terms of kernel defects, particularly starchy kernels, black pointed kernels, and shrunken kernels, mainly due to the year factor. Analyses on the whole-grain flours showed significant differences. This affected dry gluten content (7.35% to 16.40%) and gluten quality (gluten index from 6.44 to 45.81). Mixograph results for mixing time ranged from 1.90 min to 3.15 min, whilst a peak dough ranged from 6.83 mm to 9.85 mm, showing, in both cases, statistically significant differences between treatments. The falling number showed lower values during the first year (on average 305 s) and then increased in the second year (on average 407 s). The sedimentation test showed no statistically significant differences, ranging from 27.75 mm to 34.00 mm. Regarding the bread produced, statistically significant year-related differences were observed for the parameters loaf volume during the first year (on average 298.75 cm3) and then increased in the second year (on average 417.33 cm3). Weight range 136.85 g to 145.18 g and moisture range 32.50 g/100 g to 39.51 g/100 g. Hardness range 8.65 N to 12.75 N and porosity (range 5.00 to 8.00) were closely related to the type of treatment. Finally, the color of flour and bread appeared to be not statistically significantly affected by treatment type. From a perspective of environmental and economic sustainability, the use of plant extracts with a bio-herbicidal function could replace traditional chemical herbicides.

Powder bed fusion of solid and permeable Crofer 22 APU parts for applications in chemical process engineering

AbstractAdditive manufacturing of metals has attracted significant attention across various industries. However, its adoption in certain chemical and energy sectors remains constrained by the absence of optimized alloys tailored for high temperatures and corrosive environments. This study explores the laser-based powder bed fusion processing of Crofer 22 APU, a high-temperature, corrosion-resistant alloy ideal for applications such as methane steam reforming reactors, high-temperature fuel cells, and palladium membrane supports. Systematic optimization of laser parameters including laser power, hatch distance, point distance, and building angles was conducted for both dense and porous objects. Dense parts achieved a relative density of 0.9999 and surface roughness of Sa= 41.27±1.48 on a 45$$^\circ$$ ∘ overhang. Porous samples showed a porosity range of 28.655.5% and surface roughness Sa 22.2 $$\upmu$$ μ m to 45.9 $$\upmu$$ μ m as hatch distance increased from 0.12 mm to 0.16 mm. Additionally, an 8YSZ coating applied via screen printing demonstrated the impact of hatch distance and laser power on surface quality. The combination of additive manufacturing of Crofer 22 APU and screen printing of 8YSZ simplifies the preparation of metallic supports for Pd-based membranes, reducing fabrication time and cost by shortening the number of preparation steps. This technique offers a promising approach for scaling up membranes and membrane reactors.

Analysis of classification results of rock cores with different physical properties based on clustering algorithm

Abstract In response to the problem of high difficulty in development caused by different physical properties differences during water flooding in high water bearing oil fields, effective flow unit division and analysis were carried out in Zone 1 of Gangxi through flow unit analysis. The physical property classification of each rock core in the flow unit was determined using the GMM cluster algorithm. The results show that Class I flow units have high permeability and porosity, and good pore permeability performance; The porosity and permeability distribution range of Class II flow units is the widest, with some pore permeability performance comparable to or even higher than Class I, and overall pore permeability performance is good; The porosity and permeability of Class III flow units are lower than the first two types, and their pore permeability performance is relatively poor. The types of core porosity and permeability in the study area can be divided into four categories, with the majority being high permeability, ultra-high permeability, and high permeability. The new research results provide a reference basis for the study of physical property distribution and later well network deployment in the first block of Gangxi District.

Fabrication and characterization of an electrospun silk fibroin/gelatin transparent graft material for corneal epithelial regeneration

The damaged corneal epithelial causing loss of vision can be restored by epithelial tissue regeneration through tissue engineering approach that provides an engineered corneal substitute with appropriate properties and nanofibrous architecture. This works reports a polymeric matrix that was derived from silk fibroin (SF) and gelatin (GE) natural polymer blend with optimized composition resembling the structure and function of the native epithelial tissue. SF/GE blend spinning solutions prepared with different volume ratios of SF/GE: 70/30, 50/50, and 30/70 were used to fabricate electrospun mats. The fabricated two-dimensional mats had nanofibrous porous architecture having interconnected pores with pore size range of 175–267 nm suitable for corneal epithelial regeneration and 891.2–558 nm fiber diameter range as revealed by scanning electron microscopic image analysis. The performed Fourier transform infrared spectra confirmed the presence of individual polymers in the scaffolds and the scaffolds are hydrophilic in nature. Among the scaffolds, SF/GE 70:30 and SF/GE 50:50 composition possess desired porosity range of 87–88%. The tensile strength was slightly decreased with increase in GE content and the strength obtained was in the range 2.74–2.26 Mpa. An enhanced transparency was obtained with increased GE concentration, the transparency range of 73–82% observed with SF/GE:50/50 matches with the transparency of natural corneal epithelium. The biocompatibility of the scaffolds was confirmed by cell attachment, cytotoxicity and ROS evaluation by culturing rabbit corneal fibroblast cells (SIRC) on the scaffolds. Among the scaffolds, SF/GE: 70/30 exhibited the highest cell viability, but with less transparency ranging 55–71%. Therefore, considering all the properties, SF/GE with 50:50 ratio scaffold may be a suitable substrate in the field of corneal tissue engineering.