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Paper used in the printing industry generally contains a relatively thin porous coating covering a thicker fibrous base layer. The three-dimensional pore structure of coatings has a major effect on fluid flow patterns inside the paper medium. Understanding and quantifying the flow properties of thin coating layers is hence crucial. Pore spaces within the coating have an average size of about 180 nm. We used scanning electron microscopy combined with focused ion beam (FIB-SEM) to visualize the nano-scale pore structure of the paper coating layer. Post-processing of the FIB-SEM images allowed us to reconstruct the three-dimensional pore space of the coating. The 3D FIB-SEM images were analyzed in detail to obtain pore size distribution and porosity value. The permeability was estimated using the GeoDict software, based on solutions of the Stokes equation. By determining the porosity and permeability of increasingly larger domain sizes, we estimated the size of a representative elementary volume (REV) for the coating layer to be 60 µm 3 , which is well within the volume analyzed using FIB-SEM. The estimated porosity and permeability of the REV domain were 0.34 and 0.09 mDarcy, respectively. Using the pore morphology method, capillary pressure-saturation ( P c - S ) and relative permeability curves of the REV domain could be constructed next. The P c -S curves showed that the coating had a high air entry suction, which is very favorable for printing in that ink will invade the coating as soon as it is applied to the coating. Our results are essential for macroscale modelling of ink penetration into a coating layer during inkjet printing. Macroscopic models can be valuable tools for optimization of the penetration depth and the spreading of ink on and within paper substrates. [ABSTRACT FROM AUTHOR]

Modeling morphological and hydraulic properties of thin porous media, such as filter layers and papers is highly relevant to various industries. In our previous studies, the X-ray tomography and FIB-SEM methods were applied to capture micro- and nano-scale pores in uncoated paper and coated layer, respectively. Here, the reconstructed pore structures were used to investigate two-phase water imbibition in these porous media. The obtained pore size distributions showed a log-normal probability density function. Such a distribution, together with concepts from critical path analysis and percolation theory, was applied to calculate relative permeability over a wide range of water saturations. Comparison with pore-scale numerical simulations showed the capability of this method to estimate water relative permeability for coated and uncoated papers. [ABSTRACT FROM AUTHOR]

A review of non-equilibrium water flow and solute transport in soil macropores: Principles, controlling factors and consequences for water quality. Over 650 citations in the 13 years since the publication of Jarvis's ([32]) landmark paper in EJSS reflect its importance as an up-to-date review of the principles, controlling factors and environmental impacts of non-equilibrium water flow and solute transport through soil macropores. Countries with <2.5% are not shown gl The networking of soil macropores and its impact on macropore flow Skopp ([70]) classified soil pores into matrix pores and macropores, based on the difference in their efficiency in conducting water and solutes. From real soils to 3D-printed soils: Reproduction of complex pore network at the real size in a Silty-loam soil. [Extracted from the article]

In this study, uncoated paper was characterized. Three-dimensional structure of the layer was reconstructed using imaging results of micro-CT scanning with a relatively high resolution $$(0.9~\upmu \hbox {m})$$ . Image analysis provided the pore space of the layer, which was used to determine its porosity and pore size distribution. Representative elementary volume (REV) size was determined by calculating values of porosity and permeability values for varying domain sizes. We found that those values remained unchanged for domain sizes of $$400\times 400\times 150\,\upmu \hbox {m}^{3}$$ and larger; this was chosen as the REV size. The determined REV size was verified by determining capillary pressure-saturation imbibition curves for various domain sizes. We studied the directional dependence of curves by simulating water penetration into the layer from various directions. We did not find any significant difference between curves in different directions. We studied the effect of compression of paper on curves. We found that up to 30% compression of the paper layer had very small effect on the curve. Relative permeability as a function of saturation was also calculated. Water penetration into paper was visualized using confocal laser scanning microscopy. Dynamic visualization of water flow in the paper showed that water moves along the fibers first and then fills the pores between them. [ABSTRACT FROM AUTHOR]

Wt% of aragonite, a CaCO3 polymorph, increased with higher hydraulic activity (°C) of limestone in precipitated calcium carbonate (PCC) from the lime-soda process (Ca(OH)2-NaOH-Na2CO3). Only calcite, the most stable polymorph, was crystallized at hydraulic activity under 10 °C, whereas aragonite also started to crystallize over 10 °C. The crystallization of PCC is more dependent on the hydraulic activity of limestone than CaO content, a factor commonly used to classify limestone ores according to quality. The results could be effectively applied to the determination of polymorphs in synthetic PCC for eco-friendly paper manufacture. [ABSTRACT FROM AUTHOR]

First of all, the authors thank the distinguished discussers for providing helpful comments on the original paper. We are hopeful that the following comments may help with the discussion. [ABSTRACT FROM AUTHOR]

Abstract: This study investigates the predictive ability of gene-expression programming (GEP) in the estimation of methane yield (Y m ) and effluent substrate (S e ) produced by two anaerobic filters. The modeling study was carried out using the data obtained from two upflow anaerobic filters – one mesophilic (35°C) and one thermophilic (55°C) – operated for the treatment of paper-mill wastewater under varying organic loadings. The GEP model was composed of three inputs, hydraulic retention time (T hr ), organic loading rate (R ol ), and influent substrate (S i ), and one output, either S e or Y m . The Stover–Kincannon model was also used for data analysis and to evaluate the prediction ability. Three statistical criteria, root mean square error (RMSE), determination coefficient (R 2), and Akaike''s information criteria (AIC), were the means used for comparison. The results showed that the GEP approach predicted the performance of both anaerobic filters much better than the Stover–Kincannon model. [Copyright &y& Elsevier]

The article under discussion, whilst providing generalized accounts of the effects of waterflows in karstic formations, fails, in the opinion of this respondent, to substantiate the claims that an immediate threat is posed to the continued preservation of the monuments at Tāq-e Bostān, the focus of this response. [ABSTRACT FROM AUTHOR]

Bio-cemented soils can exhibit various types of microstructure depending on the relative position of the carbonate crystals with respect to the host granular skeleton. Different microstructures can have different effects on the mechanical and hydraulic responses of the material, hence it is important to develop the capacity to model these microstructures. The discrete element method (DEM) is a powerful numerical method for studying the mechanical behaviour of granular materials considering grain-scale features. This paper presents a toolbox that can be used to generate 3D DEM samples of bio-cemented soils with specific microstructures. It provides the flexibility of modelling bio-cemented soils with precipitates in the form of contact cementing, grain bridging and coating, and combinations of these distribution patterns. The algorithm is described in detail in this paper, and the impact of the precipitated carbonates on the soil microstructure is evaluated. The results indicate that carbonates precipitated in different distribution patterns affect the soil microstructure differently, suggesting the importance of modelling the microstructure of bio-cemented soils. [ABSTRACT FROM AUTHOR]

We investigated the effects of root medium pH on water transport in whole-plant and detached roots of paper birch (Betula papyrifera Marsh.). Exposure of seedling roots to pH 4 and 8 significantly decreased root hydraulic conductivity (L p) and stomatal conductance (g s), compared with pH 6. When roots of solution-culture-grown (pH 6) seedlings were transferred to pH 4 or 8, their steady-state water flow (Q v) declined within minutes, followed by a decline in g s. The root oxygen uptake rates were not significantly affected by the pH treatments. Treatment of roots with mercuric chloride resulted in a large decrease in Q v at pH 6; the extent of this decrease was similar to that brought about by pH 4 and 8. Lowering root temperature from 21 to 4 °C decreased Q v irrespective of medium pH. Low root temperatures did not offset the effects of medium pH 4 on Q v and the roots in this treatment had a high activation energy for water flow. Conversely, roots exposed to pH 8 had a low activation energy, similar to that at pH 6. When 2 µM abscisic acid, (±)-cis-trans-ABA, was added to the root medium, Q v increased in roots that were incubated at pH 6. It also increased slightly in roots incubated at pH 4, but not at pH 8. The increase at pH 4 and 6 was temperature-dependent, occurring at 21 °C, but not 4 °C. We suggest that the pH treatments are responsible for altering root water flow properties through their effects on the activity of water channels. These results support the concept that ABA effects on water channels are modulated by other, possibly metabolic- and pH-dependent factors. [ABSTRACT FROM AUTHOR]

Critical flow in irrotational motion is important in theoretical hydrodynamics and dam hydraulics. Therefore, the commented paper is relevant in theory and practice. It deals with an approximation for critical flow based on a set of simplified irrotational flow equations in the gravity field. The underlaying model equations were found by the discussers to strongly rely on Jaeger's work. Therefore, some important aspects need a detailed clarification. Jaeger's velocity profile was determined here by a possibly novel procedure starting from the irrotational flow relations in the complex potential plane. It was shown that, though not perfect, a theory assuming critical crest conditions gives consistent estimates of the discharge coefficient, crest flow depth, bottom pressure head, and velocity profile. A new method for computing the flow profile over an ogee crest is presented by simultaneous determination of the discharge coefficient and the real critical point position using the Bélanger–Böss theorem, resulting a physically based determination of the critical point in spillway flow. It is demonstrated that Jaeger's curvature parameter K is not a universal value, such that neither the current comment nor the discussed paper are therefore "free" from empirical parameters. [ABSTRACT FROM AUTHOR]

The present comment concerns some doubtful results included in the above paper. • The paper concerns the MHD squeezed flow of water functionalized metallic nanoparticles over a sensor surface. • The function for channel height is irrational and wrong. • The equation representing the transformed temperature is wrong. [ABSTRACT FROM AUTHOR]

Abstract: Surface roughness (texture) has an effect on fluid flow in networks which has been studied for well over a century. The exact effect roughness has on fluid flow has not been completely understood, but a working estimate has been offered by a variety of authors over time. The work of Colebrook, Nikuradse, and Moody has provided practitioners with a method to include at least a first order estimate of roughness effects, but their work has been limited to relative roughness (roughness height to diameter) values of 5% or less. Modern fluidic systems at the mini- and micro-levels routinely violate the 5% relative roughness threshold due to the inability to control the roughness of surfaces to sufficient levels with respect to decreasing system scale. Current work by Kandlikar et al., has extended the traditional methods of assessing surface roughness effects up to 14% relative roughness by including the effect of constricted flow diameters (modified flow diameter based on constrictions caused by surface roughness) and modifying the Moody diagram to reflect new experimental data. The future of micro fluidics would suggest that trends for miniaturization will continue and that further understanding and experimentation will be warranted. This is especially true with regards to understanding the role of roughness on the flow in mini- and micro-channels. [Copyright &y& Elsevier]

Comments on an article about fire-induced flow. Hydraulic problems in flow dynamics; Role of hot layer interface and vent neutral plate in flow dynamics; Mathematical modeling methods for fire problem analysis.