Fluid Penetration Research Articles

Lithium isotopic and fluid mobile trace element systematics of the Bay of Islands altered forearc upper to lower ophiolitic crust

Bulk rock Li isotope and select fluid mobile element traverses through the crustal section of the Late Cambrian Bay of Islands Ophiolite Complex (BOIC) in the Taconic Humber Arm Allochthon in the Newfoundland Appalachians are presented to examine the extent and conditions of alteration at different pseudo-stratigraphic levels in the ancient forearc oceanic crust that was obducted during the Middle Ordovician.N-MORB normalized enrichment factors (EFs) calculated for Li and fluid mobile elements (FMEs) show variable extents of enrichments or depletions from shallow to deep oceanic crustal sections in the BOIC that are consistent with a broad range of alteration-related δ7Li values from −2.97 to +20.69 ‰ (vs. unaltered MORB range of +1.5 to +6.1 ‰ with a mean of +3.4 ± 1.4 ‰). EFs and fluid-rock reaction modeling for Li contents and δ7Li values indicate alteration dominantly controlled enrichments and depletions of Li isotopic and FMEs systematics through all crustal levels of the BOIC ophiolite. Alteration fluids are dominated by modern seawater-like δ7Li composition rather than the recently proposed Cambrian seawater that is based on ancient carbonate shell compositions.BOIC basaltic samples proximal to the York Harbor Mine (YHM), similar to the classic mafic Cu-Zn Cyprus-type volcanic massive sulfide (VMS) deposits, show light δ7Li values of −2.97 to +1.59 ‰, but highly enriched Li contents (14.0–40.7 μg/g). Modeling results indicate that these YHM basalts were altered by metal-rich magmatic fluids, in part, derived from deeper plagiogranite intrusions near the base of the sheeted dikes that are possibly admixed with seawater-derived hydrothermal fluids below the VMS deposit. Magmatic volatile exsolution may be associated with the crystallization of directly underlying subvolcanic silicic intrusions, resulting in over-pressuring and fracturing of the carapace that may assist in localizing the high temperature (400–200 °C) upflow zones of the seafloor hydrothermal system.The BOIC layered gabbroic rocks also show evidence of variable extent of alteration as reflected by both Li content (EF both >1 and < 1) and δ7Li composition (+0.79 to +9.47 ‰), likely indicating high-temperature amphibolite (800–600 °C within the ductile deformation field) to lower temperature greenschist facies paragenesis, with down-temperature complex retrograde petrogenetic lineages. Mylonites and ductile shear zones commonly show heavier δ7Li values between +5.47 and + 18.83 ‰. We suggest that mylonite zones and coarser-grained high-strain zones allowed near-axis fluid penetration at high to lower temperatures that extended to the basal gabbroic sections in the crust during ongoing igneous activity. Shear zones were associated with rheologic weakening and initial permeable pathways for hydrothermal fluids. Shallow on-axis and deep off-axis hydrothermal circulation likely occurred at a relatively fast-spreading rate, which may account for the significant shallow to deep crustal heat extraction as predicted by the multiple sill model of lithospheric cooling.

Effectiveness of N95 Mask in Preventing COVID-19 Transmission.

N95 mask has emerged as a potential measure to mitigate the airborne transmission of respiratory disease such as COVID-19. Herein, we experimentally investigated the impact and interaction of pure water droplets as surrogate to respiratory droplets with the different layers of a commercially available N95 mask to demonstrate the penetration and passage-capability of respiratory fluids through the different layers. The penetration of an impacting droplet through the mask layers was characterized by elucidating the ejection of secondary droplets from the rear-side surface of the target mask material. In addition, the passage of respiratory fluids through the mask layers was characterized by capillary imbibition of the droplet liquid through the pores, as a function of wettability of the mask material. Droplet impact at Weber numbers We = 208 and 416 has been considered in the present study; the chosen We range corresponds to that of cough droplets realized in real respiratory events. Each layer of the N95 mask is hydrophobic that prevents capillary imbibition through the pores: a sessile droplet placed over the surface exhibits classical diffusion-limited evaporation. Droplet impact experiments on N95 mask layer surfaces reveal that a single layer allows liquid penetration at We = 416; while a combination of five layers, as is the case of a commercially available N95 mask, blocks the penetration completely, consistent with the widely known effectiveness of N95 masks. Herein, we devote special attention to compare the so-obtained efficiency of N95 masks to that of a recently designed two-layer cloth mask containing an intermediate High-Efficiency Particulate Air (HEPA) filter layer (Narayan et al. in Phys Fluids 34:061703, 2022). We conclusively show that the performance of the designed cloth mask is identical to that of a commercially available N95 mask. The assessment of mask effectiveness further includes examination of breathability and comfort by means of passage of air through them. A comparative study has been presented herein for a clear demonstration of effectiveness of different masks in preventing air-borne transmission of COVID-19.

Cutting performance of a tool with continuous lubrication of atomized cutting fluid at the tool-chip interface

To improve the tool lubrication performance and reduce the use of cutting fluid as much as possible, a new type of tool with continuous lubrication on the tool-chip contact interface has been fabricated. The atomized cutting fluid can be directly delivered to the tool-chip contact interface through the inner microchannel. Experiments were conducted on the new lubrication method, dry cutting, and traditional MQL cutting of 45 steel. The three-dimensional cutting forces and the cutting temperatures were measured. The wear surface of the rake face was analyzed through SEM micromorphology and EDS element detection. The results showed that the main cutting force of the tool with continuous lubrication at the tool-chip interface decreased by 14.5% and 5.9% compared with the conventional tools of dry cutting and MQL cutting. Moreover, the friction coefficient decreased by 14.2% and 9.8%, the length of the tool-chip contact interface decreased by 35.4% and 19.1%, and the amount of cutting fluid was only 1/10 of that in MQL cutting. The new lubrication method had better cutting fluid penetration and lubrication film formation performance than the traditional MQL method on the tool-chip interface. Furthermore, the surface wear of the new lubrication method was significantly reduced, and the main wear form of the new lubrication method was adhesive wear.

Textural and LA-ICP-MS trace element analyses reveal co-enriched Au-Sb-W metallogeny in the Woxi deposit, west Jiangnan Orogen, South China

It is well-known that tungsten and antimony are commonly enriched in the gold deposit and occur as Au-Sb or Au-W deposits. However, the Woxi deposit, located in the West Jiangnan Orogen of South China, is remarkably co-enriched in the Au-Sb-W elemental association. This deposit is characterized by multistage Au mineralization and reactivation of structures developed in the Neoproterozoic metamorphic rocks, but the detailed mechanism of its co-enriched Au-Sb-W metallogeny is still unclear. Here, we perform detailed petrographic observations and ore mineral textural and pyrite compositional analyses by using SEM and LA-ICP-MS to constrain ore-forming physiochemical conditions and to decipher the Au-Sb-W metallogenic mechanism in the Woxi deposit. The Woxi deposit consists of nine auriferous quartz lodes in the shape of stratiform, tabular, and lenticular, which are surrounded by alteration halos in the Neoproterozoic slate. These orebodies are distributed along the bedding-parallel fracture zones of the EW-striking and N-dipping in the purplish red slate of the Madiyi Formation, below the regional EW-striking Woxi fault. Four stages of hydrothermal mineralization and alteration processes could be recognized in the Woxi. Stage 1 occurs in bleached slate, and consists of euhedral, porous, and coarse auriferous pyrite (Py1), with slight arsenopyrite, siderite, and rutile. Stage 2 mainly consists of subhedral to euhedral and compositional zoning auriferous pyrite (Py2) and scheelite (Sch1), with slight wolframite and apatite hosted in quartz veinlets and native gold enclaved in Sch1. Stage 3 is characterized by scheelite (Sch2) and stibnite, with slight native gold and dendritic-shaped anhedral auriferous pyrite (Py3) hosted in quartz veins. Stage 4 features a quartz-calcite-barite-chlorite mineral assemblage that occurred as veinlets, or in the pressure shadows of Py1. Gold is mainly incorporated in the three stages (S1 to S3) of arsenian pyrite (Py1to Py3) as invisible gold and, to a lesser extent, formed visible native gold at late S2 and S3, tungsten mineralization occurs mainly as scheelite (Sch1) and wolframite at S2, with a minor amount of scheelite (Sch2) at S3, and antimony mineralization is mainly occurred as stibnite at S3. Furthermore, invisible gold most likely occurs as nanoscale particles of Au-Bi-Pb-bearing tellurides in Py1, and may be hosted in the structurally bounded lattice of Py2 and Py3.The SEM study presents highly developed dissolution-reprecipitation microstructures in hydrothermal minerals, such as pyrite, arsenopyrite, wolframite, scheelite, and apatite. Mineral paragenesis and pyrite trace element signatures suggest the ore fluid is characterized by elevated fO2, low pH and high temperature in S1, decreased fO2, medium pH and medium temperature in S2, and elevated fO2, high pH and low temperature in S3. The evolution of the physicochemical condition may be induced by penetration of multipulse ore-forming fluids and the transition of the ore-forming mechanism from fluid-rock interaction in S1 and early S2 to phase separation in late S2 and S3, as suggested by textural and LA-ICP-MS analyses. This study highlighted that coupled dissolution-reprecipitation reactions might facilitate the association of the Au-Sb-W elemental that successively mineralized and co-enriched in the Woxi deposit.

Reliability of petrogenetic information obtained from the distribution of trace elements in zircon in light of the complex infusion by foreign-element-bearing low temperature solutions

The increasing application of minor elements such as REE, Ti, Fe in zircon as petrogenetic indicators depends on zircon remaining a closed chemical system over a history that can include metamorphic events, erosion, transport, and sedimentation. Whereas examples have been described of UPb loss and element exchange during metamorphic reactions, for over 50 years there have been reports of the accumulation of a range of non-formula elements such as Ca, Al, Fe, in zircons with no metamorphic history that have been tentatively related to hydrothermal action or some other process such as weathering. This open system behaviour of zircons needs further explanation and in this contribution we present data from three zircons from a late Archaean granite from Western Australia that confirm previous observations on the distribution of non-formula elements in radiation damaged zircon and support our earlier conclusion that elements are added from percolating low temperature weathering solutions and provide new insights into the mechanisms and processes controlling access of weathering fluids into the zircon. These include radiation damage accumulation over time from the decay of U and Th to produce domains of porous amorphous material that vary in porosity and the presence of weaknesses along the boundaries of oscillatory zones which allow the penetration of low temperature groundwater fluids carrying solute elements. Also important is the size of particles of the solute elements such as Al and Ca, which depends on Eh - pH of the groundwater and porous domains within the zircon structure. This low temperature fluid interaction is distinguished from hydrothermal activity by a lack of any reaction fronts or annealing of the radiation damage and a lack of any modification of existing zircon structures. Capillary action is proposed as the mechanism driving the penetration of weathering solutions into radiation damage expansion fractures and the radiation damaged zonal structure. The susceptibility of radiation damaged zircon to infusion by low temperature fluids and deposition of accompanying solute elements has implications for the application of zircon trace element chemistry as a petrogenetic and temperature indicator as well as a geochronometer and host for nuclear waste.

New composition of chemicals and heavy drilling fluids for drilling oil and gas wells

The article shows the importance of obtaining new composition of heavy drilling fluids based on composite chemical reagents from local raw materials and industrial wastes for drilling oil and gas wells. In the process of building oil and gas wells to maintain the stability of the walls, to prevent the flow of salts, and to prevent the penetration of formation fluids into the well, it becomes necessary to increase the density of the drilling fluid, which can be accomplished by introducing components with increased density. For obtaining and stabilization heavy drilling fluid were investigated and recommended new compositions of powder water soluble gossypol resin and carboxymetylcellylose sodium and other minerals. Stabilization indexes and their determination in the drilling process of oil and gas wells have been investigated. The result of research have been implemented in the drilling process of oil and gas wells with abnormally high reservoir pressure.

Experimental Study on Influence Mechanism of Electroosmotic Effect on the Penetration and Lubrication of Water-based Cutting Fluid at Tool-chip Interface

Experimental Study on Influence Mechanism of Electroosmotic Effect on the Penetration and Lubrication of Water-based Cutting Fluid at Tool-chip Interface

Analysis of the transparent surface layer formed at the surfaces of arrested enamel caries lesions with tomographic imaging methods

BackgroundOptical coherence tomography (OCT) can acquire high-resolution images of lesion structure in vivo to assess lesion activity. The surface layers of arrested enamel caries lesions (ECLs) have a higher mineral content than the lesion body with a reduced porosity that inhibits the penetration of fluids into the lesion and appears with reduced reflectivity OCT. This study aimed to use microcomputed tomography (microCT) to measure the mineral content of the transparent surface layer (TSL) that appears on OCT images. MethodsOCT and microCT were used to measure the reflectivity and relative mineral density profiles of 20 bovine enamel samples that had simulated arrested ECLs, 44 extracted teeth with 17 proximal ECLs, 10 occlusal ECLs, and 17 lesions caused by fluorosis. TSL thickness (OCT), surface layer thickness (microCT), and the minimum and maximum densities of the TSLs were determined from matched OCT and microCT profiles. ResultsFor all samples, the TSL thickness measured with OCT was significantly less than the surface layer thickness measured with microCT (P < .05). Mean maximum mineral densities in the TSL were statistically similar to sound human enamel (P > .05) and significantly higher (P < .05) than the mean minimal mineral densities of the TSL. ConclusionsThe maximum mineral densities of the TSL measurable with OCT approach those of sound enamel suggesting that almost complete remineralization has occurred in the TSLs. This study provides further confirmation that the presence of a TSL in OCT images is a key indicator of lesion arrest.

Dynamic 18F-Pretomanid PET imaging in animal models of TB meningitis and human studies

Pretomanid is a nitroimidazole antimicrobial active against drug-resistant Mycobacterium tuberculosis and approved in combination with bedaquiline and linezolid (BPaL) to treat multidrug-resistant (MDR) pulmonary tuberculosis (TB). However, the penetration of these antibiotics into the central nervous system (CNS), and the efficacy of the BPaL regimen for TB meningitis, are not well established. Importantly, there is a lack of efficacious treatments for TB meningitis due to MDR strains, resulting in high mortality. We have developed new methods to synthesize 18F-pretomanid (chemically identical to the antibiotic) and performed cross-species positron emission tomography (PET) imaging to noninvasively measure pretomanid concentration-time profiles. Dynamic PET in mouse and rabbit models of TB meningitis demonstrates excellent CNS penetration of pretomanid but cerebrospinal fluid (CSF) levels does not correlate with those in the brain parenchyma. The bactericidal activity of the BPaL regimen in the mouse model of TB meningitis is substantially inferior to the standard TB regimen, likely due to restricted penetration of bedaquiline and linezolid into the brain parenchyma. Finally, first-in-human dynamic 18F-pretomanid PET in six healthy volunteers demonstrates excellent CNS penetration of pretomanid, with significantly higher levels in the brain parenchyma than in CSF. These data have important implications for developing new antibiotic treatments for TB meningitis.

Zonal tennantite-tetrahedrites from the Chelopech deposit: a SEM-EDS study

The composition and structure of tennantite-tetrahedrites from blocks 17 and 18 of the copper-gold high to intermediate sulphidation Chelopech deposit were determined by SEM-EDS. Based on 31 analyses is determined that the tennantites are mostly ferrous, while the tetrahedrites are zinc-rich. In zonal tennantite-tetrahedrite aggregates, sharp saw-shape chalcopyrite bands are evidence of coupled dissolution-precipitation reactions, during the replacement of the former. The fine oscillatory zoning in other tennantite crystals also is related predominantly to internal “self-organization” processes rather than external. In some cases, however, the irregular boundaries between tennantite matrix and tetrahedrite rims and strips and their variable thickness could be due to uneven penetration of fluid into the crystal along the weak zones as a result of replacement rather than overgrowth.

Location estimation of subsurface fluid-filled fractures: Cepstral predominant peak analysis and numerical study

In various subsurface resource development or fluid piping transportation problems, subsurface fluid-filled fractures often appear. Fracture location determination has always been critical in the related fields. Acoustic wave reflection at the junction and boundary in the pipeline can carry information about the property of the system. By using the accompanying acoustic wave information combined with the water hammer effect, the location of subsurface fractures can be estimated. A numerical fluid flow model for instantaneous shut-in is presented based on the water hammer effect. Fluid penetration effects, wellbore storage effect, and fluid inertial effect are considered. A method for determining the locations of subsurface fractures using cepstral predominant peak (CPP) is first proposed. By cepstral, we mean the inverse Fourier transform of the logarithm of the estimated signal spectrum. Also, the relationship between instantaneous shut-in pressure and cepstrum response is investigated in detail. To improve the robustness, CPP analysis based on Kaiser windowed cepstrum is used to identify the impulse period of fracture. Compared with the original cepstrum, Kaiser windowed cepstrum has the better performance for CPP analysis. The proposed flow model is impactful as it can provide pressure data with known fracture locations. Meanwhile, the data can be used to optimize and examine the performance of CPP analysis with Kaiser windowed cepstrum. A field experiment is conducted to validate the analysis about the acoustic wave in a pipeline system with fractures. By installing a high-frequency pressure monitoring device at the pump, the actual instantaneous shut-in pressure for an oil well is obtained. The experiment results show that the CPP analysis can obtain the fracture location efficiently and accurately, which can provide insights for engineering practices.

Geothermal Exploration in the Burwash Landing Region, Canada, Using Three-Dimensional Inversion of Passive Electromagnetic Data

Sustainable development of Canada’s North requires an increased focus on renewable, zero-emission energy sources. Burwash Landing in Yukon is prospective for geothermal energy based on a high geothermal gradient, local occurrence of warm groundwater and proximity to the active, crustal-scale Denali fault. Uncertainties about the potential geothermal system include the nature and geometry of fluid pathways, and heat sources required to drive a hydrothermal system. In this study, we inverted three passive electromagnetic datasets—321 extremely low frequency electromagnetic, 33 audiomagnetotelluric and 51 magnetotelluric stations—to map the subsurface electrical structure to 8 km depth. Our new model reveals vertical conductive structures associated with the two main faults, Denali and Bock’s Creek, which we interpret to represent fluid-deposited graphite and hydrothermal alteration, respectively. Our model supports an interpreted releasing bend on the main Denali fault strand. This is associated with the deepest conductivity anomaly along the fault and potential for deeper penetration of fluids. Enigmatic conductive bodies from 1 to &gt; 6 km depth are associated with intermediate to mafic intrusions. Fluids released from these bodies may advect heat and provide a possible heat source to mobilize hot fluids and sustain a geothermal system in the region.

Experimental Investigation on the Impacts of Fracture Roughness and Fluid Composition on the Formation of Bubble Bridges through the Microbubble Fluid Flow.

The colloidal gas Aphron (CGA) drilling fluids are an alternative to ordinary drilling mud to minimize formation damage by blocking rock pores with microbubbles in low-pressure or depleted reservoirs. Fractured formations usually have different characteristics and behavior in contrast to conventional ones and need to be investigated for Aphron applications. In this research, a series of core flood tests were conducted to understand the factors controlling the pore-blocking mechanisms of microbubbles in fractured formations. For the first time, a synthetic metal plug was used to simulate the fracture walls and eliminate the formation matrix effect. This study analyzed the effects of three fluid compositions, considering the polymer and surfactant concentrations at reservoir conditions, including temperature and overburden pressure. Additionally, fracture surface roughness as one of the parameters affecting the microbubble fluid penetration through the fracture path and bubble blockage were studied. The results indicated that microbubble fluid composition would not affect the bubble size or blockage probability. The different stable microbubble fluids resulted in the same pattern and conditions. Besides, fluid penetration would be more challenging if the fracture roughness decreased. Due to the accumulation of bubbles and the fact that some of them were trapped in the fracture's rough surface, the blockage possibility increased. According to the range of roughness for the steel core in previous studies and compared with the roughness of carbonate reservoir rocks, the roughness of fractured reservoir rocks is much higher than that of the steel surface. Accordingly, the observed trend in the experiments showed that when it is possible to form a bubble bridge in steel cores, then in carbonate rocks, we will definitely see blockage with any roughness, provided that other parameters are acceptable.

Effects of rheological stratification and elasticity of lithosphere on subduction initiation

The breaking and bending of rigid and elastic lithosphere was probably essential for the initiation of plate subduction, although how this occurred is still poorly understood. Here we test effects of rheological stratification and elasticity of lithosphere on subduction initiation, which are possibly resulting from thermal cracking and seawater penetration into the lithosphere. In addition to the strong influence of water on rheological behavior, the material rigidity is also sensitive to the development of crack and fluid saturation. Numerical modeling indicates that water-weakening and a low-rigidity lithosphere are essential for the initiation of plate subduction, and such conditions are likely to have arisen on the early Earth due to extensive thermal contraction of the planet. Our results indicate that the formation of thermal cracks and penetration of seawater play an important role on subduction initiation, and are likely to have operated on planets other than Earth. However, if the ocean is disappeared, fluid penetration is likely to cease and plate tectonics would have stopped due to increasing the strength and rigidity of the lithosphere.

Improvement of fluid penetration in soil by plasma blasting

Improvement of fluid penetration in soil by plasma blasting

Significance of porous elliptical cylinder on the MHD natural convection

In this analysis, the significance of different alignments of porous elliptical cylinder and orientation of magnetic field intensity on the buoyancy driven flow and heat transfer traits in an enclosure is investigated through lattice Boltzmann technique. Various amalgamations of the orientations of curved porous cylinder and magnetic field are carried out for the first time, which is essential in real-time applications like compact electronic devices, nuclear reactor cooling, and heat exchangers. The classical outcome of the individual parameters considered in the study can be altered through different combinations, and this information serves for the favourable heat transfer performance. This parametric study focuses on the effects of buoyancy force (Ra=104, 105, &106), non-dimensional permeability (Da=10−5, 10−4, &10−3), magnetic field intensity (Ha=0, 25, & 50), magnetic field orientation (γM=0°, 45°, &90°), and orientation of the porous elliptical cylinder (Case-1=0°, Case-2=30°, Case-3=45°, &Case-4=90°) on the hydro-thermal behaviour in and around the porous cylinder. The Darcy–Brinkman–Forchheimer equation is linked with the LB flow evolution equation to obtain the flow features of porous medium. It is observed that the flow-field intensity in and around the porous zone is directly proportional the imposed buoyancy force and permeability. Unsteady traits in flow and thermal fields are seen at higher Ra and Da when the porous body is not streamlined. The amount of fluid penetration and the distance travelled by it in the porous zone are the deciding factors for the heat transfer variation of different orientations of the porous cylinder. The sway of buoyancy force on the heat transfer intensification is hampered by the intensity of magnetic field. In the case of Θ=0° the % increment in mean Nusselt number (NuM) at Ra=105 with respect to Ra=104 is 108.2%, 66.6%, & 18.2% for Ha=0, 25, & 50, respectively. Although, magnetic field has displayed adverse influence on the thermal performance, by tuning the orientation of the magnetic force, the heat transfer can be significantly improved (about 9.3% increment when γM=90°, Ra=106&Da=10−3). The impact of magnetic field and its orientation are found to be significant when the buoyancy force and permeability are more. At lower permeabilities of the cylinder, the streamlined shape offered higher heat transfer rate, whereas, at higher permeabilities such pattern reverses. Besides, it is seen that few amalgamations of parameters embraced in the study offered a drastic variation in flow and heat transfer behaviour.

Effect of electroosmosis on lubricant penetration at the tool–chip interface

Conventional microcapillary lubrication theories explain lubricant penetration into capillaries at the tool–chip interface under the action of atmospheric pressure and capillary force without considering the electrokinetic effect caused by triboelectrification. In this study, the effect of electroosmosis on the penetration of water-based cutting fluid at the tool–chip interface of a turning process was investigated for the first time. An ionic adsorption model was proposed to adjust the zeta potential of different tool and workpiece materials in fluids, and a self-excited electric field at the tool–chip interface was obtained using an exoelectron emission test. The electroosmotic force related to the zeta potential and electric field intensity can regulate electrically driven fluid penetration. Cutting tests with a fixed self-excited electric field indicated that the cutting force obtained using a higher zeta potential fluid was lower than that obtained using deionized water and reversed zeta potential fluids (e.g. significant declines of 31.1 % and 44.3 % in AISI 304 turning). Moreover, scanning electron microscopy and energy dispersive X-ray spectroscopy analyses on the worn tool edges produced using the above fluids indicated a transfer from adhesive wear to micro breakage, which explains the positive correlation between penetration and zeta potential, owing to an elevated electroosmosis effect. The results presented in this paper are significant for understanding the influence of the electroosmosis effect on lubricant penetration to perfect the microcapillary lubrication theory and provide a reference for formulating metal working fluids.

Functional Encapsulating Structure for Wireless and Immediate Monitoring of the Fluid Penetration (Adv. Funct. Mater. 31/2022)

Functional Encapsulating Structure for Wireless and Immediate Monitoring of the Fluid Penetration (Adv. Funct. Mater. 31/2022)

Coating of a viscoplastic material onto a moving porous web during forward roll coating process: A theoretical study

In this paper, a mathematical model of forward roll for coating a thin viscoplastic fluid onto a moving porous web is developed when the web passes through a small gap between the two rigid rolls. The conservation equations in the light of lubrication approximation theory are non-dimensionalized and solutions for the velocity profile, flow rate, pressure distribution are calculated numerically by using Range-Kutta-Fehlberg’s method. It is found that by changing (increasing/decreasing) the material parameters, one can really control the engineering quantities like velocity distribution, flow rate, pressure distribution, and penetration depth The velocity graphs show that the gap between the velocity curves decrease, as fluid moves toward the separation point. This has a significant effect on the final volume of fluid flowing as at the separation point the fluid splits evenly. It was also found that the degree of fluid penetration is affected by the web flexibility and permeability. It has also been found that viscoelastic parameter and ratio of viscous to elastic forces have great impact on the emerging parameters, furthermore, the pressure gradient has been significantly affected with the variation in permeability and deformability. It is worth mentioning that the present study is a quick reference for the engineer working in coating industries and to compare the results with experimental data. Some results are shown graphically.

Hydraulic Fracturing of Soft and Hard Rocks: Part 1—Rock Behavior Due to Fluid Penetration Rate

Hydraulic Fracturing of Soft and Hard Rocks: Part 1—Rock Behavior Due to Fluid Penetration Rate