Fluid Permeability Research Articles

PERCOLATION CHARACTERISTICS OF POWER-LAW FLUID IN THE FRACTAL TREE-LIKE BIFURCATION NETWORKS WITH ROUGH SURFACES

In order to study the seepage characteristics of power-law fluids in the fractal tree-like bifurcation networks with rough surfaces based on fractal theory, the shape factor of rough surfaces is treated as the randomly distributed cones. According to the generalized Darcy's law and the constitutive equation of power-law fluids, the fully-developed laminar and incompressible flow of power-law fluids in rough pipelines is explored, and the velocity graduation and flow rate expressions of fluids in rough pipelines are obtained. Then, the fractal model for the permeability of power-law fluid in the tree-like bifurcation network with rough surfaces is proposed, and the total flow rate, total pressure drop, and permeability of power-law fluid in the tree bifurcation network with rough surfaces are derived. The relative increase in pressure and the relative decrease in permeability are also obtained. Finally, the analytical expression for the permeability of power-law fluids is analyzed. It can be seen that the permeability of a rough tree-like bifurcation network is inversely proportional to relative roughness, length ratio, bifurcation angle, etc., and directly proportional to the power-law index and diameter ratio. At the same time, the predicted values of the model are compared with existing models, proving the correctness and rationality of the model.

Division and Effect Evaluation of Fracking Outburst Elimination Zones in Surface Extraction Wells of Coalbed Methane

Surface hydraulic fracturing is an important measure for increasing reservoir permeability, which has advantages such as engineering safety and a large impact range and can be implemented ahead of the mine’s underground engineering. However, its underground outburst reduction range and effect are rarely reported, and there is a lack of connection with underground fracturing wells. Taking coalbed methane wells in the Lu’an Mining Area as an example, underground observation, microseismic monitoring, and numerical simulation methods were used to study the fracturing range and outburst control effect of surface wells. The fracturing zone of coalbed methane wells is approximately elliptical in shape, with the main fractures extending along the direction of the maximum horizontal principal stress. It can be divided into five zones: sand laying zone (radius of 140~150 m), fracture propagation zone (radius of about 180 m), fracturing fluid permeability zone (width of about 1 m), gas surge zone (width of 2~3 m), and final desorption zone (width of about 2 m). The stress around the fracturing zone increases along the direction of maximum and minimum principal stresses, while the stress value within the zone decreases, with a range of approximately 5~20% of the original geostress. The outburst reduction index Δh2 in the fracturing zone significantly decreased after fracturing. The percent of Δh2 (< 150 Pa) increased from 38.3% to 100% after fracturing. A model for evaluating the effectiveness of surface fracturing and outburst prevention was proposed, and the model was used in Tunliu Mine. The results showed that the standard‐reaching rate of extraction was high, and the danger of outburst could be completely eliminated. The research results can provide a reference for the arrangement of the coalbed methane wells and can also provide effective guidance for outburst prevention and control work during mining and excavation on a more macro scale. It provides a new idea and method for making up for the shortcomings such as the small impact range and safety hazards of underground fracturing.

Modeling and semi-analytical solution for immiscible and miscible fingers formation during enhanced oil recovery

ABSTRACT The fingering phenomenon arises during the secondary and tertiary oil recovery processes when injected fluid (water, gases, nano/biomaterials, or polymer particles) shoots through a porous medium at a relative speed. Oil recovery is influenced by various factors including the fluid type, capillary pressure, permeability, and porous material structure. All these elements play crucial roles in determining the success and efficiency of the oil recovery process. Many scientists have debated the fingering phenomenon from different perspectives. Here, we developed mathematical models with and without considering mass flow rates of oil and water for an inclined oil layer flowing through a homogenous porous medium to generate immiscible fingers. Furthermore, a mathematical model of miscible viscous finger formation with carbonated water injection (flooding) during the enhanced oil recovery process (EOR) has been analyzed in this paper. To solve each of these mathematical models, we used the recently developed approach known as the Method of Directly Defining the inverse Mapping (MDDiM). We found approximate solutions to the nonlinear partial differential equations (PDEs), which describe each modeling of the fingering phenomenon in a homogeneous porous medium by incorporating gravitational effects for several types of flooding and discussed the effects of the saturation rate.

An Overview of the Updates of Management of Pulmonary Edema: Narrative Review

The development of abrupt respiratory failure linked to fluid buildup in the lung's alveolar spaces due to an elevated heart-filling pressure is known as pulmonary oedema. Pulmonary oedema can result from any cardiac condition marked by a rise in left ventricular pressure. Long-term high capillary pressure can potentially break down the barrier, resulting in increased fluid transfer and permeability into the alveoli and atelectasis and oedema. Numerous variables, such as dysregulated inflammation, strong leukocyte infiltration, activation of procoagulant processes, cell death, and mechanical stress, contribute to the disruption of the alveolar-epithelial barrier. In order to properly treat patients with pulmonary oedema, a thorough medical history and a physical examination are necessary to assess the condition's symptoms and possible causes. In the interim, second-level diagnostic procedures such as echocardiography, chest radiograph, natriuretic peptide level, and pulmonary ultrasonography should be performed. To determine the best course of treatment for these patients, it is imperative to identify the unique pulmonary oedema phenotype. Early in the course of treating this illness, non-invasive ventilation should be taken into consideration. For pulmonary congestion, diuretics and vasodilators are employed. Vasopressors and inotropes are sometimes needed to address hypoperfusion. Additional strategies (i.e., beta-agonists and pentoxifylline) may be beneficial for patients with diuretic resistance and chronic symptoms. The pathogenesis, clinical manifestation, and therapy of pulmonary oedema are reviewed in this publication.

Influence of conical graded porous architecture on the mechanical, failure behavior and fluid-flow properties for bone scaffold application

IntroductionThe advanced design of the controllable hierarchical gradient architecture of functionally graded porous scaffold is gaining increasing attention in tissue engineering (TE). This paper proposed a new design gradient concept of Schwartz-Primitive (Sch-P) conical graded porous architecture by integrating linear and radial graded patterns. Materials and Methods: Four types of gradient pattern structures with similar 80 % porosity were designed and fabricated using polylactic acid (PLA) pro via material extrusion. The structural compression test was performed to evaluate the mechanical properties in order to validate the computational analysis. In addition to that, computational fluid dynamics (CFD) was conducted to predict the permeability and fluid-induced wall shear stress (WSS) of porous structures. Results: The experimental result shows that conical graded structures exhibit the highest mechanical strength in terms of elastic modulus (64.84 MPa), yield stress (1.83 MPa), and total energy absorption (1.115 J/m3) compared to linear, radial, and uniform structures. The unique smooth surfaces of the conical pores arrangement resulted in excellent strength with a localized fracture in the shape of a chevron and global fracture in a layer-by-layer failure mechanism. Indeed, the permeability values for conical graded meets the fluid permeability of actual cancellous bone. Conclusion: The findings highlighted that conical graded structure offered superior mechanical characteristics with improved energy absorption and failure behavior as well as fluid-flow properties. It indicates that conical graded meets all the mechanical and biological requirements to mimic the cancellous bone, especially in load-bearing applications.

A Study on the Production Simulation of Coal–Shale Interbedded Coal Measure Superimposed Gas Reservoirs under Different Drainage Methods

To study the influence of different drainage methods on the production performance of coal measure gas wells, the interbedded reservoir composed of coal and shale in the Longtan Formation of the Dahebian block was used as the research object. Considering the influence of coal and shale matrix shrinkage, effective stress, and interlayer fluid flow on reservoir properties such as fluid migration behavior and permeability, a fluid–solid coupling mathematical model of coal measure superimposed gas reservoirs was established. Numerical simulations of coal measure gas production under different drainage and production modes were conducted to analyze the evolution of reservoir pressure, gas content in the matrix, permeability, and other characteristic parameters of the superimposed reservoir, as well as differences in interlayer flow. The results showed that, compared to single-layer drainage, cumulative gas production increased by 33% under multi-layer drainage. Both drainage methods involve interlayer energy and substance transfer. Due to the influence of permeability, porosity, and mechanical properties, significant differences exist in reservoir pressure distribution, preferential flow direction, gas content in the matrix, and permeability ratio between coal and shale reservoirs under different drainage and production modes. Multi-layer drainage effectively alleviates the influence of vertical reservoir pressure differences between reservoir layers, facilitates reservoir pressure transmission in shale reservoirs, enhances methane desorption in shale matrices, promotes matrix shrinkage, and induces the rebound of shale reservoir permeability, thus improving overall gas production.

μCT ANALYSIS AND 3D MODELLING OF COMPARATIVE FLUID PERMEABILITY OF HUMAN TALI FOLLOWING THREE DIFFERENT CLINICAL PROCEDURES: NANOFRACTURE, MICROFRACTURE, AND FINE WIRE DRILLING

AbstractObjectivesThe aim of this work was to compare the different techniques and the different fluid permeability of the tissue following each technique through assessing the flow of radiopaque contrast agent using μCT image analysis and 3D modelling.MethodsDonated human tali specimens (n=12) were prepared through creating a 10mm diameter chondral defect in three different regions of each talus. Each region then underwent one of three surgical techniques: 1) Fine wire drilling, 2) Nanofracture or 3) Microfracture, equidistant sites in each defect to ensure even distribution. Each region then had an addition of 0.1 ml radiopaque contrast agent (Omnipaque™ 300), imaged using a clinical μCT scanner (SCANCO Medical AG, 73.6 μm resolution). Each μCT scan was segmented using Slicer 3D software (The Slicer Community, 2023 3D Slicer (5.2.2)). The segmentation package was used to segment the bone and contrast agent regions in each different surgical site of each sample. Each defect site was created into a cylinder and the ratio of segmented pixels of contrast agent against bone.ResultsThe μCT analysis indicated that across the 12 samples, eight nanofracture regions demonstrated flow of the contrast agent either to the depth of the fracture site or deeper. Some lateral flow was also observed in these sites. eight microfracture regions demonstrated that the flow of the contrast agent was localised to the fracture site and a preferential flow laterally. In only one sample, did a fine wire drilling region demonstrate any fluid flow. In this sample, contrast agent had permeated through the drilling site to the bottom and some sub-site permeation was observed. However, in all samples that showed no permeation of contrast agent through the fracture site, a layer of contrast agent on the chondral surface or minor permeation through to the sub-chondral surface. Segmentation of each sample site showed a significant increase (n=12, p<0.05) in fluid flow of the contrast agent in the nanofracture sites (11%) compared to microfracture (5%) and fine wire drilling (2%).ConclusionsNanofracture showed significantly improved fluid permeability throughout the surrounding trabecular structure, when compared to microfracture and fine wire drilling. Microfracture appears to allow some fluid flow, but only confined to the immediate area around the fracture site, while fine wire drilling appears to allow a comparably small amount, if not no fluid flow through the surrounding trabecular tissue. This conclusion is reinforced by previous literature that concluded the damage to the structure of the trabecular tissue is reduced when using nanofracture, compared to the other two techniques.Declaration of Interest(a) fully declare any financial or other potential conflict of interest

Infiltration Grouting Mechanism of Bingham Fluids in Porous Media with Different Particle Size Distributions

Although permeation grouting technology has been widely used in engineering practice, there has not been sufficient research on how the distribution of pore sizes in porous media affects the diffusion of grout. In this study, based on the fractal theory of porous media and the Bingham fluid rheological equation, a Bingham fluid permeation grouting mechanism considering the distribution of pore sizes in porous media is proposed. The mechanism is validated through laboratory experiments and numerical simulations using COMSOL 6.0. During the experiments, parallel electrical resistance imaging is employed to monitor the diffusion range of the grout. Furthermore, the effects of grouting pressure, porosity, and water–cement ratio on the diffusion radius of the grout are analyzed. The results show that the Bingham fluid grout diffuses in a semi-spherical shape in the gravel. Additionally, parallel electrical resistance imaging can analyze the diffusion range of the grout in the gravel. The diffusion radius of the Bingham fluid grout in the gravel is smaller than the diffusion radius obtained by considering the particle size distribution theory, with an average difference of 31.8%. Compared to the diffusion radius obtained without considering the particle size distribution theory, the diffusion radius obtained by considering the distribution of pore sizes is closer to the experimental results. The numerically simulated program, which was developed for this study, can effectively simulate the diffusion law of the Bingham fluid in the gravel. So far, the Bingham fluid seepage grouting model considering the different particle size distribution of porous media has been built. The findings of this study can provide theoretical support and technical reference for practical grouting projects.

Attenuation of Rayleigh and pseudo surface waves in saturated soil by seismic metamaterials

Seismic metamaterials have received extensive research interest due to their bandgap properties, simplicity in design principles, and stability in response. They have been developed to protect buildings or architectures susceptible to damage from surface elastic waves. In practice, the ground soil is generally a multiphase medium, and the influence of its permeability and viscosity on seismic metamaterials is not yet clear. In this work, we developed a formulation that combines Biot’s theory and Bloch-Floquet theorem to investigate the complex band structures and transmission properties of Rayleigh and pseudo surface waves (PSWs) for pillared and inclusion-embedded seismic metamaterials in saturated soil. It is shown that the ratio of fluid viscosity and permeability η/κ have an impact on the surface wave attenuation and the performances of seismic metamaterials, where the smaller ratio benefits the surface wave broadband attenuation and metamaterials attenuating effects. The complex band structures reveal that inclusion-embedded metamaterials can support the propagation of PSWs having a phase velocity higher than that of the transverse bulk waves. The PSWs are significantly affected by the rubber viscosity due to the mode displacements concentrated in the rubber coatings. The higher viscosity of metamaterials also allows for broadband attenuation of Rayleigh surface waves. The results of this study will present an appropriate way to design viscoelastic seismic metamaterials in saturated soil for low-frequency surface wave attenuation.

Enhancement of carbon dioxide storage efficiency using anionic surfactants

The injection of carbon dioxide into aquifers under the cap rock involves high capillary pressure, resulting in reduced injection efficiency as the distance from the injection well increases. Capillary pressure, determined by the interfacial tension (σ) and contact angle (θ) between immiscible fluids, significantly influences this process. Previous studies examined surfactant properties such as the interfacial tension and contact angle, aiming to enhance carbon dioxide injection efficiency. Most of the existing research in this field has focused on the enhancement of oil recovery. Therefore, this study conducted micromodel experiments and pore network simulations to assess the impact of anionic surfactants, namely SDS and SDBS, on the efficiency of carbon dioxide injection into submarine aquifers. The results of micromodel experiments showed a substantial improvement in injection efficiency with higher injection rates and the incorporation of surfactants. However, no significant influence on injection efficiency was shown between surfactant concentrations of 0.01 wt% and 0.02 wt%. The numerical analysis showed that interfacial tension more influenced on injection efficiency than the contact angle. Moreover, the introduction of surfactants resulted in an increased relative fluid permeability, concomitant with increased injection efficiency. Consequently, the utilization of surfactants holds significant promise in increasing the injection efficiency of carbon capture and storage (CCS).

Gas-dynamic processes and causes of accidents at mines

Geodynamic phenomena that occur during the exploitation of a coal-bearing massif lead to human casualties, reduce the speed of penetration, and significantly complicate the operation of the mine.The article analyzes existing views on geodynamic processes occurring within mining fields located in coal-bearing formations. A safe technology for identifying potential outburst locations during coal mining is characterized. The technology has been tested during prospecting and environmental studies within the mining workings at active mines and abandoned mining fields. The results of profile and planar investigations in he areas exhibiting geodynamic outbursts in coal deposits and mines are presented.When sampling subsoil air using the technology of structural-thermo-atmospheric-hydrogeochemical research (STAHGS), which is carried out on the surface of the earth in profile and planar versions, the authors came to the conclusion about the possibility of predicting fault zones of increased permeability and zones of low fluid permeability. The first affect the rate of destruction of rocks under pressure, and in the second case, the possibility of gas emissions into the mine, which can be accompanied by an explosion and fire. Such zones are dangerous, because the most destructive events occur in places of collision. Early identification of places of geodynamic stress of rocks, fault zones of increased permeability, accumulation of gases – all this will allow to make a decision in advance about changing the conditions of conducting mining operations and degassing of the coal massif.In addition, the authors draw attention to hydrogen gas as one of the causes of initiation of explosions and fires during underground mining operations in mines, which is not taken into account at the current stage of safety control of mining operations. The possible cause of a hydrogen explosion is not taken into account in coal mine accidents. The appearance of hydrogen and helium in coal samples taken from the mine may indicate the deformation of the massif, which leads to the opening of cracks and the outflow of gas from deeper horizons. And then an increase in the concentration of hydrogen, not methane, creates the conditions for explosions and fires.

Hydro-mechanical modelling of swell behaviour of bentonite buffer

Hydro-mechanical modelling of swell behaviour of bentonite buffer

PB0766 Decreased Compactness and Increased Fluid Permeability of Ex-Vivo Fibrin Clots in Patients After Traumatic Brain Injury

PB0766 Decreased Compactness and Increased Fluid Permeability of Ex-Vivo Fibrin Clots in Patients After Traumatic Brain Injury

Using fracture-based continuum modeling of coupled geomechanical-hydrological processes for numerical simulation of hydraulic fracturing

This paper describes numerical simulation of hydraulic fracturing using fracture-based continuum modeling (FBCM) of coupled geomechanical-hydrological processes to evaluate a technique for high-density fracturing and fracture caging. The simulations are innovative because of modeling discrete fractures explicitly in continuum analysis. A key advantage of FBCM is that fracture initiation and propagation are modeled explicitly without changing the domain grid (i.e. no re-meshing). Further, multiple realizations of a preexisting fracture distribution can be analyzed using the same domain grid. The simulated hydraulic fracturing technique consists of pressurizing multiple wells simultaneously: initially without permeating fluids into the rock, to seed fractures uniformly and at high density in the wall rock of the wells; followed by fluid injection to propagate the seeded fracture density hydraulically. FBCM combines the ease of continuum modeling with the potential accuracy of modeling discrete fractures and fracturing explicitly. Fractures are modeled as piecewise planar based on intersections with domain elements; fracture geometry stored as continuum properties is used to calculate parameters needed to model individual fractures; and rock behavior is modeled through tensorial aggregation of the behavior of discrete fractures and unfractured rock. Simulations are presented for previously unfractured rock and for rock with preexisting fractures of horizontal, shallow-dipping, steeply dipping, or vertical orientation. Simulations of a single-well model are used to determine the pattern and spacing for a multiple-well design. The results illustrate high-density fracturing and fracture caging through simultaneous fluid injection in multiple wells: for previously unfractured rock or rock with preexisting shallow-dipping or horizontal fractures, and in situ vertical compressive stress greater than horizontal. If preexisting fractures are steeply dipping or vertical, and considering the same in situ stress condition, well pressurization without fluid permeation appears to be the only practical way to induce new fractures and contain fracturing within the target domain.

Fluid seepage mechanism and permeability prediction model of multi-seam interbed coal measures

The successful development of coal measure gas (CMG) in the Surat Basin in Australia shows that the geological conditions of thin-interbed CMG development may be more favorable, but the above understanding is still in the geological law summary level. This study combines numerical simulation and physical simulation experiments to study the core geological problems of CMG in the geological control of the permeability of a multi-thin coal seam composite reservoir (MTCCR). The results show that in the initial stage of stress loading, the permeability advantage of the coal-mudstone/sandstone composite reservoir is reflected in the bedding permeability. Based on this phenomenon, the concept of “cross-layer seepage effect of fluid in MTCCR” is proposed for the first time, which is analyzed as the result of the permeation effect of adjacent rock fluids in the composite reservoir under the action of pressure difference. The numerical simulation shows that the permeability increase of the MTCCR depends on the increase in the fracture, and the coupling effect of the fracture and pore changes the fluid pressure field and seepage mode around the fracture. From the experimental perspective, the above understanding confirms the results of previous conclusions on the geological law of high permeability of MTCCR, and explains the geological phenomenon of high permeability of MTCCR from the seepage mechanism. Based on numerical and physical simulation experiment, a sedimentation-tectonics controlled permeability prediction model was constructed. The seepage mechanism and the permeability prediction model established of MTCCR in this study can provide theoretical support and quantitative basis for the selection of high permeability zones and evaluation of high permeability sections in the exploration and development process of thin interbed CMG.

Angioedema with normal complement studies: What do we know?

Angioedema is generally readily recognizable clinically and is characterized by localized nonpitting edema involving subcutaneous, submucosal, or deep dermal tissue caused by increased vascular permeability and extravasation of intravascular fluid. It can occur via a variety of mechanisms. A number of clinical conditions (masqueraders) are occasionally mistaken for angioedema. Clinical classification of the various angioedema forms begins with noting the presence or absence of concurrent urticaria or wheals. Pathogenesis can be considered through two broad categories: mast cell-mediated with release of vasoactive mediators causing angioedema usually associated with urticaria or in the context of an anaphylactic reaction; and bradykinin (BK)-driven, in which increased vascular permeability is mediated by BK. BK-mediated angioedema does not occur with urticaria, nor does it respond to antiallergic medications. The various forms of hereditary angioedema are included in this category, requiring specific tests of C4 and C1 inhibitor level and function to confirm the diagnosis. Angiotensin converting enzyme inhibitors, which impair the degradation of BK, account for up to a third of all patients with angioedema presenting to the emergency department. Finally, angioedema may occur by yet unknown mechanisms; under this circumstance, it is difficult to manage.

Dynamic Evolution of Porosity in Lower‐Crustal Faults During the Earthquake Cycle

AbstractEarthquake‐induced fracturing of the dry and strong lower crust can transiently increase permeability for fluids to flow and trigger metamorphic and rheological transformations. However, little is known about the porosity that facilitates these transformations. We analyzed microstructures that have recorded the mechanisms generating porosity in the lower crust from a pristine pseudotachylyte (solidified earthquake‐derived frictional melt) and a mylonitized pseudotachylyte from Lofoten, Norway to understand the evolution of fluid pathways from the coseismic to the post‐ and interseismic stages of the earthquake cycle. Porosity is dispersed and poorly interconnected within the pseudotachylyte vein (0.14 vol%), with a noticeably increased amount along garnet grain boundaries (0.25–0.41 vol%). This porosity formed due to a net negative volume change at the grain boundary when garnet overgrows the pseudotachylyte matrix. Efficient healing of the damage zone by fluid‐assisted growth of feldspar neoblasts resulted in the preservation of only a few but relatively large interconnected pores along coseismic fractures (0.03 vol% porosity). In contrast, porosity in the mylonitized pseudotachylyte is dramatically reduced (0.02 vol% overall), because of the efficient precipitation of phases (amphibole, biotite and feldspars) into transient pores during grain‐size sensitive creep. Porosity reduction on the order of >85% may be a contributing factor in shear zone hardening, potentially leading to the development of new pseudotachylytes overprinting the mylonites. Our results show that earthquake‐induced rheological weakening of the lower crust is intermittent and occurs when a fluid can infiltrate a transiently permeable shear zone, thereby facilitating diffusive mass transfer and creep.

The alteration of illite by Bad Nauheim and Gerolstein brine; Implications on fluid permeability in geothermal systems

Illite is one of the most abundant clay minerals on earth, yet its structure remains not fully solved. In hydrothermal reservoir sandstones, illites can display a fibrous growth within the pores and pore throats. The network created by them and the particles trapped therein during fluid flow lead to a dramatic decrease in permeability, which should be prevented if the reservoirs were to be used for geothermal energy extraction. In order to determine possible changes in structure, stacking or shape of the illite fibers, the interaction of a sandstone with two different brines was compared to an unaltered sandstone via environmental scanning electron microscopy and transmission electron microscopy. Moreover, three-dimensional electron diffraction experiments were performed using automated diffraction tomography. The 1Mtv structure of illite could be solved based on a single dataset of a 50 nm illite fiber. Illites that were altered with synthetic Gerolstein brine showed one-dimensional diffuse scattering, indicating a disorder in the stacking of the illite layers. The degree of disorder is dependent on the potassium content of the fluid, since the K+ ions of the interlayer can be released via the (010) facet. This causes a stability reduction of the structure, resulting in a high fragmentation and detachment of individual illite layers. Fluids interacting with the sandstone can then transport such mobile layer fragments, leading to entangling and interweaving of illite fibers. These new insights into the structure of illite fibers show a significant dependence of the arrangement of the fibers in the pores on the potassium content of the fluid. The increased migration and interweaving of illite fibers associated with a low potassium content can lead to severe clogging of the pores and thus to a reduction in fluid permeability. Altered sandstones with illitic pore filling are therefore less suitable for long-term geothermal projects.

On the reduction of the flow-induced noise using porous material plates with high acoustic transmissibility

This study investigates the efficacy of closed-structure porous materials for reducing flow-induced noise, given their high acoustic transmissibility and low fluid permeability. A multifaceted approach encompassing wind tunnel experiments, numerical simulations, and practical applications to heating, ventilation, and air-conditioning (HVAC) systems in commercial electric vehicles was adopted. Wind tunnel experiments demonstrated a significant reduction, over 20 dB, in the tonal noise generated from a rectangular cylinder and an increase in its frequency, attributable to changes in the vortex structure and velocity fluctuations in the wake of the cylinder. The numerical simulation of fluid permeation and pressure wave conditions on the surface of the porous material as a boundary condition aligned with the experimental outcomes, suggesting that such permeation conditions could lead to noise and drag reduction. Practical testing showed a 5 dB noise reduction at the driver's ear position when porous materials were attached to a portion of an electric vehicle's HVAC system. The noise reduction was associated with changes in velocity fluctuations in the flow field, aligning with the wind tunnel experimental findings. This study provides promising insights into the development of effective noise reduction strategies using porous materials.

Effective permeability of an immiscible fluid in porous media determined from its geometric state

Based on Darcy's law, two-fluid flow is dependent on a relative permeability function of saturation only that is process/path dependent with an underlying dependency on pore structure and wettability. We develop an Artificial Neural Network (ANN) that relies on fundamental geometrical measures to determine relative permeability. The developed ANN is based on a prescribed set of state variables based on physical insights that predicts the relative permeability of 4,500 unseen pore-scale geometrical states with ${R}^{2}$ = 0.98.