The impact of pore structure and surface roughness on capillary trapping for 2‐D and 3‐D porous media: Comparison with percolation theory

<p>Porous media surface roughness strongly influences the transport of solutes during drainage, due to the formation of thick water films (capillary condensation) on the porous media surface. In the case of interfacial-reacted, water-based solutes, these water films increase both the production of the solute, due to the increased number of fluid-fluid interfaces, and the loss of the solute by the retention in the stagnant water films. The retention of the solute in flowing water is described by a mobile mass retention term. This study applies the pore-scale direct simulation with the phase-field method based continuous solute transport (PFM-CST) model on the kinetic interfacial sensitive (KIS) tracer reactive transport during primary drainage in a 2D slit with a wall with variable fractal geometries. The capillary-associated moving interface is found to be larger for rough surfaces than smoother ones. The results confirm that the impact of roughness regarding the film-associated interfacial area can be partly, or totally masked, in a drained slit. It is found that the mobile mass retention term is increased with larger volumes of capillary condensed water films. To conclude, it is also found that the surface roughness factor has a non-monotonic relationship with the overall production rate of solute mass in moving water.</p>

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PORE STRUCTURE RECONSTRUCTION AND MOISTURE MIGRATION IN POROUS MEDIA

Fractals ◽

10.1142/s0218348x14400076 ◽

2014 ◽

Vol 22 (03) ◽

pp. 1440007 ◽

Cited By ~ 4

Author(s):

JIAYI ZHENG ◽

XING SHI ◽

JUAN SHI ◽

ZHENQIAN CHEN

Keyword(s):

Porous Media ◽

Water Vapor ◽

Diffusion Process ◽

Pore Structure ◽

Pore Size ◽

Spectral Dimension ◽

Anisotropic Porous Media ◽

Vapor Diffusion ◽

Water Vapor Diffusion ◽

The Impact

Three kinds of porous media (isotropic, perpendicular anisotropic and parallel anisotropic porous media) with the same porosity, different pore size distributions and fractal spectral dimensions were reconstructed by random growth method. It was aimed to theoretically study the impact of microscopic pore structure on water vapor diffusion process in porous media. The results show that pore size distribution can only denote the static characteristics of porous media but cannot effectively reflect the dynamic transport characteristics of porous media. Fractal spectral dimension can effectively analyze and reflect pores connectivity and moisture dynamic transport properties of porous media from the microscopic perspective. The pores connectivity and water vapor diffusion performance in pores of porous media get better with the increase of fractal spectral dimension of porous media. Fractal spectral dimension of parallel anisotropic porous media is more than that of perpendicular anisotropic porous media. Fractal spectral dimension of isotropic porous media is between parallel anisotropic porous media and perpendicular anisotropic porous media. Other macroscopic parameters such as equilibrium diffusion coefficient of water vapor, water vapor concentration variation at right boundary in equilibrium, the time when water vapor diffusion process reaches a stable state also can characterize the pores connectivity and water vapor diffusion properties of porous media.

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Experimental study of the supercritical CO 2 diffusion coefficient in porous media under reservoir conditions

Royal Society Open Science ◽

10.1098/rsos.181902 ◽

2019 ◽

Vol 6 (6) ◽

pp. 181902 ◽

Cited By ~ 1

Author(s):

Junchen Lv ◽

Yuan Chi ◽

Changzhong Zhao ◽

Yi Zhang ◽

Hailin Mu

Keyword(s):

Porous Media ◽

Diffusion Coefficient ◽

Oil Recovery ◽

Carbon Capture ◽

Carbon Capture And Storage ◽

Elevated Pressure ◽

Experimental Results ◽

Saturated Porous Media ◽

Reservoir Conditions ◽

The Impact

Reliable measurement of the CO 2 diffusion coefficient in consolidated oil-saturated porous media is critical for the design and performance of CO 2 -enhanced oil recovery (EOR) and carbon capture and storage (CCS) projects. A thorough experimental investigation of the supercritical CO 2 diffusion in n -decane-saturated Berea cores with permeabilities of 50 and 100 mD was conducted in this study at elevated pressure (10–25 MPa) and temperature (333.15–373.15 K), which simulated actual reservoir conditions. The supercritical CO 2 diffusion coefficients in the Berea cores were calculated by a model appropriate for diffusion in porous media based on Fick's Law. The results show that the supercritical CO 2 diffusion coefficient increases as the pressure, temperature and permeability increase. The supercritical CO 2 diffusion coefficient first increases slowly at 10 MPa and then grows significantly with increasing pressure. The impact of the pressure decreases at elevated temperature. The effect of permeability remains steady despite the temperature change during the experiments. The effect of gas state and porous media on the supercritical CO 2 diffusion coefficient was further discussed by comparing the results of this study with previous study. Based on the experimental results, an empirical correlation for supercritical CO 2 diffusion coefficient in n -decane-saturated porous media was developed. The experimental results contribute to the study of supercritical CO 2 diffusion in compact porous media.

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Waterfall Algorithm as a tool of investigation the geometrical features of granular porous media

Computational Particle Mechanics ◽

10.1007/s40571-021-00430-0 ◽

2021 ◽

Author(s):

Wojciech Sobieski

Keyword(s):

Particle Size ◽

Porous Media ◽

Lattice Boltzmann ◽

Granular Media ◽

Density Ratio ◽

Geometrical Features ◽

Granular Porous Media ◽

Collision Density ◽

Boltzmann Method ◽

The Impact

AbstractThe paper describes the so-called Waterfall Algorithm, which may be used to calculate a set of parameters characterising the spatial structure of granular porous media, such as shift ratio, collision density ratio, consolidation ratio, path length and minimum tortuosity. The study is performed for 1800 different two-dimensional random pore structures. In each geometry, 100 individual paths are calculated. The impact of porosity and the particle size on the above-mentioned parameters is investigated. It was stated in the paper, that the minimum tortuosity calculated by the Waterfall Algorithm cannot be used directly as a representative tortuosity of pore channels in the Kozeny or the Carman meaning. However, it may be used indirect by making the assumption that a unambiguous relationship between the representative tortuosity and the minimum tortuosity exists. It was also stated, that the new parameters defined in the present study are sensitive on the porosity and the particle size and may be therefore applied as indicators of the geometry structure of granular media. The Waterfall Algorithm is compared with other methods of determining the tortuosity: A-Star Algorithm, Path Searching Algorithm, Random Walk technique, Path Tracking Method and the methodology of calculating the hydraulic tortuosity based on the Lattice Boltzmann Method. A very short calculation time is the main advantage of the Waterfall Algorithm, what meant, that it may be applied in a very large granular porous media.

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Smoothing additive manufactured parts using ns-pulsed laser radiation

Progress in Additive Manufacturing ◽

10.1007/s40964-021-00168-4 ◽

2021 ◽

Author(s):

Florian Kuisat ◽

Fernando Lasagni ◽

Andrés Fabián Lasagni

Keyword(s):

Surface Roughness ◽

Mechanical Performance ◽

State Of The Art ◽

Pulsed Laser ◽

Industrial Applications ◽

Laser Source ◽

Pulsed Laser Radiation ◽

Current State ◽

The Impact

AbstractIt is well known that the surface topography of a part can affect its mechanical performance, which is typical in additive manufacturing. In this context, we report about the surface modification of additive manufactured components made of Titanium 64 (Ti64) and Scalmalloy®, using a pulsed laser, with the aim of reducing their surface roughness. In our experiments, a nanosecond-pulsed infrared laser source with variable pulse durations between 8 and 200 ns was applied. The impact of varying a large number of parameters on the surface quality of the smoothed areas was investigated. The results demonstrated a reduction of surface roughness Sa by more than 80% for Titanium 64 and by 65% for Scalmalloy® samples. This allows to extend the applicability of additive manufactured components beyond the current state of the art and break new ground for the application in various industrial applications such as in aerospace.

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Nature instigated Grey wolf algorithm for parametric optimization during machining (Milling) of polymer nanocomposites

Journal of Thermoplastic Composite Materials ◽

10.1177/0892705721993202 ◽

2021 ◽

pp. 089270572199320

Author(s):

Prakhar Kumar Kharwar ◽

Rajesh Kumar Verma

Keyword(s):

Surface Roughness ◽

Cutting Force ◽

Polymer Nanocomposites ◽

Feed Rate ◽

Fitness Function ◽

Depth Of Cut ◽

Multiwall Carbon Nanotube ◽

Grey Wolf ◽

Milling Characteristics ◽

The Impact

The new era of engineering society focuses on the utilization of the potential advantage of carbon nanomaterials. The machinability facets of nanocarbon materials are passing through an initial stage. This article emphasizes the machinability evaluation and optimization of Milling performances, namely Surface roughness (Ra), Cutting force (Fc), and Material removal rate (MRR) using a recently developed Grey wolf optimization algorithm (GWOA). The Taguchi theory-based L27 orthogonal array (OA) was employed for the Machining (Milling) of polymer nanocomposites reinforced by Multiwall carbon nanotube (MWCNT). The second-order polynomial equation was intended for the analysis of the model. These mathematical models were used as a fitness function in the GWOA to predict machining performances. The ANOVA outcomes efficiently explore the impact of machine parameters on Milling characteristics. The optimal combination for lower surface roughness value is 1.5 MWCNT wt.%, 1500 rpm of spindle speed, 50 mm/min of feed rate, and 3 mm depth of cut. For lower cutting force, 1.0 wt.%, 1500 rpm, 90 mm/min feed rate and 1 mm depth of cut and the maximize MRR was acquired at 0.5 wt.%, 500 rpm, 150 mm/min feed rate and 3 mm depth of cut. The deviation of the predicted value from the experimental value of Ra, Fc, and MRR are found as 2.5, 6.5 and 5.9%, respectively. The convergence plot of all Milling characteristics suggests the application potential of the GWO algorithm for quality improvement in a manufacturing environment.

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Structural Changes in French VF Treatment Wetland Porous Media during the Rest Period: An Ex Situ Study Using X-ray Tomography

Water ◽

10.3390/w13030389 ◽

2021 ◽

Vol 13 (3) ◽

pp. 389

Author(s):

German Dario Martinez-Carvajal ◽

Laurent Oxarango ◽

Jérôme Adrien ◽

Pascal Molle ◽

Nicolas Forquet

Keyword(s):

Porous Media ◽

Structural Changes ◽

Rest Period ◽

Treatment Wetlands ◽

Ex Situ ◽

Initial Value ◽

Treatment Wetland ◽

X Ray ◽

The Impact ◽

Deposit Layer

Clogging constitutes a major operational issue for treatment wetlands. The rest period is a key feature of French Vertical Flow (VF) treatment wetlands and serves to mitigate clogging. An ex-situ drying experiment was performed to mimic the rest period and record structural changes in the porous media using X-ray Computed Tomography (CT). Samples containing the deposit and gravel layers of a first stage French VF treatment wetland were extracted and left to dry in a control environment. Based on CT scans, three phases were identified (voids, biosolids, and gravels). The impact of the rest period was assessed by means of different pore-scale variables. Ultimately, the volume of biosolids had reduced to 58% of its initial value, the deposit layer thickness dropped to 68% of its initial value, and the void/biosolid specific surface area ratio increased from a minimum value of 1.1 to a maximum of 4.2. Cracks greater than 3 mm developed at the uppermost part of the deposit layer, while, in the gravel layer, the rise in void volume corresponds to pores smaller than 2 mm in diameter. Lastly, the air-filled microporosity is estimated to have increased by 0.11 v/v.

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