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The response of airfoils to unsteady disturbances is a classic problem in the aerodynamics field. Many theoretical models have been proposed in the past to predict the unsteady aerodynamic forces of airfoils. However, these theories focused on individual airfoil motions or incoming flow disturbances, while the theoretical models for multiple disturbances still need to be developed. In this study, a theoretical model to predict the aerodynamic force of an oscillating airfoil encountering vertical gust is derived from a linear combination of Theodorsen's and Sears' theories. Experimental investigations involving a two-dimensional pitching airfoil encountering a sinusoidal vertical gust are carried out to examine the proposed theory. It is found that the theory effectively captures the trends in the unsteady lift of airfoils subjected to dual disturbances. However, it tends to overestimate the lift amplitude. Notably, when a quasi-steady correction is applied to the theory, the prediction accuracy is greatly improved. The theory correction agrees well with experiment at small pitching frequencies, while deviations exist at higher pitching frequencies. The temporal evolution of the flow velocity reveals that the velocity disturbance induced by the coupled disturbance around the airfoil conforms to the linear superposition of the velocities induced by each individual disturbance, consistent with the prediction of the vortex sheet model. As the pitching frequency increases, significant nonlinear effects appear near the trailing edge of the airfoil, which may be one key factor for the disparities between the theoretical predictions and the experimental lift at higher pitching frequencies. [ABSTRACT FROM AUTHOR]

The response of airfoils to unsteady disturbances is a classic problem in the aerodynamics field. Many theoretical models have been proposed in the past to predict the unsteady aerodynamic forces of airfoils. However, these theories focused on individual airfoil motions or incoming flow disturbances, while the theoretical models for multiple disturbances still need to be developed. In this study, a theoretical model to predict the aerodynamic force of an oscillating airfoil encountering vertical gust is derived from a linear combination of Theodorsen's and Sears' theories. Experimental investigations involving a two-dimensional pitching airfoil encountering a sinusoidal vertical gust are carried out to examine the proposed theory. It is found that the theory effectively captures the trends in the unsteady lift of airfoils subjected to dual disturbances. However, it tends to overestimate the lift amplitude. Notably, when a quasi-steady correction is applied to the theory, the prediction accuracy is greatly improved. The theory correction agrees well with experiment at small pitching frequencies, while deviations exist at higher pitching frequencies. The temporal evolution of the flow velocity reveals that the velocity disturbance induced by the coupled disturbance around the airfoil conforms to the linear superposition of the velocities induced by each individual disturbance, consistent with the prediction of the vortex sheet model. As the pitching frequency increases, significant nonlinear effects appear near the trailing edge of the airfoil, which may be one key factor for the disparities between the theoretical predictions and the experimental lift at higher pitching frequencies. [ABSTRACT FROM AUTHOR]

When the airlift bioreactor is applied to the field of industrial fermentation, there is a common problem of low mixing and flow efficiency due to its simple structure. In order to expand the application of airlift bioreactor in the field of industrial fermentation, a new type of airlift bioreactor with three-dimensional bumps in the draft tube has been designed to enhance the mixing and flow of gas-liquid two-phase in the reactor. In order to determine the specific influence of the three-dimensional bumps on the internal flow field of the reactor, and to provide technical reference for the improvement of the structure of the airlift bioreactor, in this paper, the CFD simulation of this type of bioreactor is carried out. Based on the Euler multiphase flow, the Realizable k-ε model was used to analyze the flow field of the reactor with average gas-liquid flow linear velocity and temperature as parameters. The results show that under certain conditions, the three-dimensional bumps inside the draft tube can effectively accelerate the gas-liquid two-phase flow and better promotes the mixing of pig manure fermentation broth and air. [ABSTRACT FROM AUTHOR]

Achieving a harmonious alignment between the biological characteristics of fish and hydrodynamics patterns is crucial for ensuring the efficacy of fish passage facilities. In this study, based on the hydrodynamic characteristics of the river and the biological characteristics of fish, we evaluated the internal flow field in the nature-like fishway of Congen II hydropower station located along the Chabao river and explored methods to improve the operation efficiency. Based on comprehensive considerations of the flow field, turbulent kinetic energy, and the migration pathways of fish, it is found that the implementation of a continuous oblique bottom slope represents a more cost-effective and operationally convenient solution. The influence of different permutation of bulkheads in the nature-like fishway on operational efficiency was further examined. Our investigation revealed that the nature-like fishway with the continuous slope of 2% and the arrangement of three bulkheads in each row (model 3) exhibited a relatively simple velocity distribution and linear flow line, which poses challenges for fish in locating resting areas. In addition, the distribution of low turbulence kinetic energy area in the mainstream made it less favorable for fish to transition from the mainstream to the rest area within the fishway. The nature-like fishway with the continuous slope of 2% and the arrangement of two or three bulkheads in staggered rows (model 4) demonstrated better performance. Several potential fish migration routes for both model 3 and model 4 were proposed based on the numerical simulation results. In model 3, fish exhibited a continuous sprint through the concentrated high-speed area, which was less favorable for fish to rest and forage. In contrast, model 4 exhibited a diversified flow velocity distribution, enabling fish to make timely changes in their direction during migration. This feather proved to be advantageous in enhancing fish migration within the passage. The design of nature-like fishway in this study provides an important reference and technical support for the construction and optimization of the nature-like fishway for low dams, and is of great significance for restoring river connectivity destroyed by small hydropower construction and improving fish migration. [ABSTRACT FROM AUTHOR]

Results of studying stabilization of a homogeneous hydrogen–air flame on an optical discharge plasma in a high-velocity flow are reported. The main aspect of experiments is providing stable combustion behind the region of laser beam focusing without any mechanical flame holders. The laser radiation parameters are sufficient for creating a quasi-steady plasma in the flow. It is shown that the optical discharge stabilizes the flame front in a wide range of equivalence ratios for flow velocities up to m/s. The laser radiation parameters within the range of their variation from one experiment to another exert a minor effect on the turbulent flame velocity. Flame stabilization behind the optical discharge region has some specific features. An important parameter is heat release due to hydrogen combustion. A dimensionless criterion is derived: the turbulent flame velocity is a linear function of this criterion. [ABSTRACT FROM AUTHOR]

A developed stationary two-dimensional turbulent flow of an incompressible fluid in channels and pipes is studied. The entire flow was divided into three zones: a laminar zone near the boundaries of the channel (pipe) and a transition and turbulent ones that follow. The laminar zone and part of the transition zone were combined into one zone, for which a linear flow velocity profile was assumed in the channel and a parabolic velocity profile with corresponding additional functions in the pipe. For the zone consisting of a turbulent core and the rest of the transition zone, a logarithmic flow velocity profile was taken. Comparison of the results of calculations with experimental data has been carried out, which has shown their acceptable agreement. [ABSTRACT FROM AUTHOR]

The major goal of this research is to establish a new theory of generalized thermoelasticity for thermomass gas flow with low velocity and linear resistance based on the general non-Fourier law of heat conduction. The resistance effect has been included in the general heat conduction equation, which is based on the total derivative of the thermomass gas velocity. Using the governing equations of that unique model, two numerical applications of homogeneous, isotropic, and thermoelastic one-dimensional rods have been constructed. The two applications were solved using the Laplace transform and numerical inversion methods. In terms of thermal and mechanical wave distributions, the latest findings illustrate the contrasts between the Lord–Shulman model and the present revolutionary thermoelasticity model. The parameters of the current general non-Fourier equation of heat conduction have a major impact on thermomechanical waves. [ABSTRACT FROM AUTHOR]

An analysis is made of unstable perturbations of a geostrophic current of finite transverse scale with a vertical parabolic velocity profile of a general form (with linear and constant velocity shear) in a vertically bounded layer. The model is based on the potential vortex equation in the quasi-geostrophic approximation taking into account the vertical diffusion of momentum and mass. The equation and boundary conditions are reduced to a spectral eigenvalue problem of the Orr–Sommerfeld type. To search for eigenfunctions and eigenvalues, a high-precision analytic–numerical method was used. Particular attention is paid to the study of unstable perturbations with a phase velocity exceeding the maximum flow velocity. Such instability should be distinguished from baroclinic instability and critical layer instability. It is found that the indicated instability can develop in ocean currents when the problem parameters vary in a wide range of values. It is also obtained that, at an increase in the Prandtl number, the phase velocity of such perturbations increases and can significantly exceed the maximum flow velocity. However, the occurrence of such unstable perturbations is possible only when the maximum flow velocity is located in the inner region of the layer (but not necessarily in its center). It has also been found that narrow currents (the transverse scale is equal to or smaller than the Rossby radius) with a parabolic vertical profile can be unstable. The most unstable perturbations have approximately equal scales along and across the flow; that is, they are circular perturbations. A discussion of various types of geostrophic current instability with a vertical parabolic velocity profile as applied to the ocean is presented. [ABSTRACT FROM AUTHOR]

Changes in the velocity of cerebral blood flow may significantly contribute to the formation of age-related cerebrovascular diseases. The age-related dynamics in cerebral blood flow velocity indicators were studied here in rats at different stages of aging. Using Doppler ultrasound, the blood flow in the cortex and subcortical structures of the cerebral hemispheres was comparatively analyzed by linear velocity values and blood flow indices in young (4-month-old) and aging (18- and 23-month-old) Sprague–Dawley rats. It was found that aging is accompanied by changes in the parameters of cerebral blood flow in the cortex and subcortical structures of the rat brain, which develop gradually and differ at different stages of aging. By the age of 18 months, perfusion in the frontal and parietal hemispheric regions increases due to an increase in peak velocities and mean velocity per cardiac cycle, as well as a decrease in the level of cerebrovascular resistance. These processes precede the development of hypoperfusion-induced blood flow disorders observed at later stages of aging. Hypoperfusion-related changes in 23-month-old rats are most pronounced in the frontal region of the cerebral hemispheres, being characterized by a decrease in peak velocities and an increase in blood flow indices. [ABSTRACT FROM AUTHOR]

Void formation as a result of irregular resin flow at the flow front is discussed and a practical method for reducing void formation during resin transfer molding (RTM) is introduced. In this study, a sensor system is developed for in situ measurement of resin velocity inside a closed cavity. Assisted by the acquired data, a resin injection system is augmented to automatically adjust the injection pressure and achieve a uniform flow front velocity. It is proven, that the developed system is suited to monitor the resin flow front and is able to sufficiently control flow velocity of a linear flow front. Test specimen produced by this method show significantly reduced void contents in comparison to a common resin transfer molding process. [ABSTRACT FROM AUTHOR]

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This paper presents an innovative hybrid water treatment process combining electrocoagulation (EC) and active chlorine-based PEF-like (PEF-like) methods to eliminate a complex mixture of tannery dyes. The solution contained Acid Blue 113 (AB 113), Acid Blue 29 (AB 29), and Brilliant Green (BG) dyes in concentrations between 300 and 750 mg L−1 COD in 2000 mg L−1 Cl − , 638 mg L−1 NH 4 + and 1700 mg L−1 SO 4 2 − at neutral pH (resembling wastewater). The influence of mean linear flow velocity (0.69 ≤ u ≤ 3.47 cm s−1), applied current density (6 ≤ j ≤ 22 mA cm−2), and initial COD on the EC removal efficiency and discoloration was systematically examined. EC removed 32–48% COD; this modest depletion is due to the high load of organic matter. On the other hand, the •OH and HClO produced in the PEF-like process were insufficient to mineralize the organic matter (52–76%) due to the high initial COD. The latter suggested that the PEF-like process requires a previous EC to reduce the COD. The synergy between EC + PEF-like (hybrid process) allowed the COD abatement. The dye removal efficiency followed the order EC < PEF-like < EC + PEF-like. The hybrid process fulfilled the Mexican standard (COD < 210 mg L−1, and 100% discoloration) with total treatment costs of 0.683–0.696 USD m−3. XRF, XRD, SEM-EDS, OEA, and FTIR analyses on iron flocs indicated that AB 29, AB 113, and BG dyes are removed by adsorption. HPLC techniques followed the maleic and malic acids and ammonium and sulfate ions during the incineration of the dyes. The hybrid technology is promising for treating real wastewater containing complex dye mixtures. [ABSTRACT FROM AUTHOR]

The problem of a plane unsteady potential flow of an ideal incompressible fluid bounded by free boundary segments with a constant pressure and by solid walls moving in accordance with a known law is considered. External forces are absent, and capillary forces are neglected. An approach to constructing exact solutions for this type of problem is proposed. The corresponding solutions can be treated as nonlinear perturbations of a certain base flow. As an example of the application of this approach, nonlinear perturbations in a known problem of a fluid flow with a linear velocity field in the region bounded by a straight-line free boundary and parallel approaching or receding solid walls are considered. It is demonstrated that perturbations grow, which leads to variants of the formation of singularities on the free surface of the fluid within a finite time: formation of droplets, bubbles or cusps. A solution describing the collapse of a bubble in a fluid layer bounded by two approaching solid walls has also been found and studied. Thus, a new method of studying nonlinear stability of complicated unsteady fluid flows with combined boundary conditions is proposed and tested. [ABSTRACT FROM AUTHOR]

The development of new home‐made stationary phases involves their packaging procedure and is crucial to obtain satisfactory working parameters. The parameter that illustrates the quality of the packed bed is its efficiency measured as the height equivalent to the theoretical plate. According to the Van Deemetr's equation, it depends on three factors, but only one of them, eddy diffusion, does not depend on the linear flow velocity. Therefore, in order to obtain it as low as possible, it is necessary to focus on a good filling of the column. Among many parameters affecting the quality of column packing, in our work we have focused on the choice of slurry solvent. Novel stationary phases with an embedded phosphodiester group were investigated. The suspensions in 16 solvents and solvent mixtures were studied for their stability, aggregation, sedimentation, and viscosity comparison. The efficiency of the packed microcolumns and its comparison was determined by chromatographic analyses using a polar (thymidine) and a nonpolar compound (naphthalene). The results obtained led to the conclusion that for these stationary phases, the best slurry solvent is the one that aggregates the phase while maintaining stability and having high viscosity. [ABSTRACT FROM AUTHOR]

The symmetric (inertial) parametric instability of time-periodic flows with a linear velocity profile has been investigated, with a complete account for the Coriolis force in the problem. The possibility of instability is shown at velocity shears smaller than those indicated by the criterion of inertial stability of a stationary flow with the same velocity amplitude. The most significant results are obtained in the limit of weak density stratification of the medium, which is characteristic of well-mixed vertically convective layers of the atmosphere, in the deep layers of the ocean, and can also be directly related to a laboratory experiment. [ABSTRACT FROM AUTHOR]

[Display omitted] • Optimal integration of POT and MABAS technologies is applied to maritime glaciers. • 3-D surface flow of the glacier ensemble in the Namcha Barwa during 2019–2022 is first mapped. • The problem of long-term linear flow velocity is successfully solved. • Two fast-moving glaciers are detected in the Namcha Barwa glacier ensemble. • The flow velocity of maritime glaciers and meteorological factors are significantly correlated. In reaction to a warming climate in the Southeastern Tibetan Plateau (SETP), the direction and intensity of surface flow in maritime glaciers undergo adjustments, causing glacial debris flow and ice avalanches. The safe operation of mega transportation projects across the region has been seriously threatened, e.g., the Sichuan-Tibet transportation corridor. Consequently, the measurement in three dimensions (3-D) consistently merits attention in the surface flow evolution for this glaciated region. In this study, we first mapped the 3-D and long-term surface flow of the glacier ensemble in the Namcha Barwa during 2019–2022 using the space-borne Synthetic Aperture Radar (SAR) technique, specifically applying the pixel offset tracking (POT) method to obtain deformation estimation of SAR-derived data. Subsequently, 3-D glacier velocities were acquired from the Multidimensional Small Baseline Subset (MSBAS) method conducted with the above datasets. Results show that two fast-moving glaciers were detected in the glacier ensemble, namely Dem Glacier and Namjagbrawa Glacier. Dem Glacier mainly flows eastward horizontally with a velocity of approximately 120 m/yr. And the inconspicuous vertical changes reveals that the glacier has sufficient winter supply. Although the detectable proportion of Namjagbrawa Glacier is relatively small, SAR results can perform well in limited pixels verified through optical results. It flows swifter over roughly −150 m/yr in the east, north, and vertical directions due to the vast elevation differences. However, other glaciers in the ensemble generally maintained slow flow, with multidimensional velocities below 20 m/yr. All glaciers' flow velocities and the local climate in temporal are parallelism in the variations, which exhibit summer-accelerated and winter-slowed seasonal patterns. There were no surge signs during the study phase, which does not preclude the possibility of future emergence. The maritime glaciers in the SETP should be therefore multidimensional and continuous monitored to implement early warning and forecasting for mega transportation projects. [ABSTRACT FROM AUTHOR]

The quantification of the enantiomers of racemic substances is of great importance in the development and regulation of pharmaceutical compounds. Active ingredients are often chiral; typically, only one of the stereoisomers has the desired pharmacokinetic and/or pharmacodynamic properties. Therefore, the stereoisomer distribution of chiral drug products must be characterized and evaluated during the drug discovery and development pipeline. Moreover, various chiral drugs present a stereoselective metabolism, highlighting the need for appropriate analytical strategies for the stereoselective analysis of metabolites, for example, in clinical and environmental studies. Due to its ease of use, robustness, and transferability, chiral liquid chromatography (LC) is the most common approach used in pharmaceutical analysis. Compared with LC, supercritical fluid chromatography (SFC) allows higher linear flow velocities while maintaining high chromatographic efficiency, often enabling the reduction of analysis time. In addition, SFC provides enhanced or complementary chiral selectivity and avoids or reduces toxic solvents, such as those used in normal-phase LC. In the first part of this review article the theoretical advantages, technological developments, and common practices in chiral SFC are discussed. This will be followed by a contribution discussing recent applications in pharmaceutical, clinical, forensic, and environmental analysis. [ABSTRACT FROM AUTHOR]

Stainless steel 316L specimens were snug fitted into a rotating disk submerged in molten LBE and subjected to spatially varying local flow velocity along the radial position. The specimens experienced LBE flow velocity from 0.50 m/s to 3.14 m/s depending on their radial location. The test was conducted at 600°C with an oxygen concentration of 2.87 × 10−8 wt% for 150 h. Resulting microstructural characteristics of the corroded zone were found to be sensitively affected by local flow velocity and were categorized into four regimes. For linear disk velocity > 2.0 m/s, the affected zone thickness became increasingly less sensitive to flow velocity as the overall reaction became reaction rate controlled. At the velocity of ~ 3.0 m/s, erosion-corrosion started to take place. The flow effect on the affected zone thickness (l ) agreed with the model based on the disk velocity (v ) effect on the mass transfer of a rotating disk as 1 l ∼ v - 0.792 . [ABSTRACT FROM AUTHOR]

In this study, the applicability of electrodialysis for aprotic imidazolium ionic liquid concentration and recovery was investigated. The recovery of the ionic liquid 1-butyl-3-methylimidazolium chloride was examined, and its degree of concentration, current efficiency, as well as energy consumption was determined. The effects of the applied voltage, ionic liquid concentration, linear flow velocity, and the type of ion-exchange membrane on the ionic liquid recovery and concentration were examined. A 2.5-fold concentration of 1-butyl-3-methylimidazolium chloride with a recovery of 86.9% and current efficiency of 92.8% was achieved with heterogeneous membranes. It was also found that the surface morphology and wettability of the heterogeneous AM(H) -- CM(H) membranes before and after electrodialysis were unchanged, in contrast to the homogeneous FAB-PK -- FKB-PK membranes, where surface changes occurred. [ABSTRACT FROM AUTHOR]

We investigate the hadron transverse momentum (pT) spectra in Pb–Pb (Pb–Pb, Xe–Xe, p–Pb) collisions at 2.76 (5.02, 5.44, 5.02) TeV in the framework of the Tsallis blast wave model with a linear transverse velocity profile and a constant velocity profile. In this model, the Tsallis temperature (T), the average radial flow velocity (⟨β⟩) and the degree of non-equilibrium (q) of the system are common for all hadrons when a combined fit is performed to the pT spectra of different particles at a given centrality. It is found that the model can describe the particle spectra well up to 3 GeV c−1. For both profiles, the transverse flow velocity decreases from central to peripheral collisions while the non-extensive parameter q exhibits the opposite behavior, indicating a more rapid expansion and reduced off-equilibrium of the system in more central collisions. Moreover, we observe that, in central collisions, ⟨β⟩ and q (T) from the fit with the linear profile are smaller (is slightly larger) than those (that) from the constant profile, while in peripheral collisions ⟨β⟩, T and q from the linear profile are compatible with those from the constant profile. We also derived and discussed the relation between the Tsallis temperature and the thermal temperature. In addition, to check whether a scenario of an early freeze-out of strange particles exists at the Large Hadron Collider, the particle spectra are investigated by grouping them into strange and non-strange hadrons. The combined fit gives an insight on the degree of non-equilibrium, the radial flow and the Tsallis temperature of the system at the kinetic decoupling. It provides a comparison between the results at different energies in the same collision system and the results in different collision systems at the same or similar energy. [ABSTRACT FROM AUTHOR]

Electrodialysis has been used for treating toxic substances such as heavy metals and minimizing secondary environmental pollution problems effectively. However, electrodialysis depends on the operating parameters as well as fluid dynamics and electrical properties. This study provides design elements for the treatment of heavy metal-containing wastewater by electrodialysis. We found that the limiting current density (LCD) is proportional but not completely linear to the diluate concentration over a threshold value. In contrast, it is linear to the linear flow velocity for the whole range. As the number of cell pairs increases, because linear flow velocity and LCD increase, the removal efficiency of heavy metals also increases. Therefore, for highly concentrated wastewater, increasing the linear flow velocity, the applied voltage, and the number of cell pairs can effectively improve removal efficiency. It was found that the current efficiency is as low as 17% when the removal efficiency of heavy metals exceeds 95%. Thus, it is necessary to select an operating range that optimizes the operating and initial investment costs for the effective removal of heavy metals using electrodialysis. [ABSTRACT FROM AUTHOR]

Soluble guanylyl cyclase (sGC) protein is a heterodimer formed by two subunits encoded by GUCY1A1 and GUCY1B1 genes. The chromosomal locus 4q32.1 harbors both of these genes, which has been previously significantly associated with coronary artery disease, myocardial infarction, and high blood pressure. Blood pressure is influenced by both the environment and genetics and is complemented by several biological pathways. The underlying mechanisms associated with this locus and its genes still need to be investigated. In the current study, we aimed to establish the zebrafish as a model organism to investigate the mechanisms surrounding sGC activity and blood pressure. A zebrafish mutant gucy1a1 line was generated using the CRISPR-Cas9 system by inducing a 4-bp deletion frameshift mutation. This mutation resulted in a reduction of gucy1a1 expression in both heterozygote and homozygote zebrafish. Blood flow parameters (blood flow, arterial pulse, linear velocity, and vessel diameter) investigated in the gucy1a1 mutants showed a significant increase in blood flow and linear velocity, which was augmented in the homozygotes. No significant differences were observed for the blood flow parameters measured from larvae with individual morpholino downregulation of gucy1a1 and gucy1b1 , but an increase in blood flow and linear velocity was observed after co-morpholino downregulation of both genes. In addition, the pharmacological sGC stimulator BAY41-2272 rescued the impaired cGMP production in the zebrafish gucy1a1 ± mutant larvae. Downregulation of cct7 gene did not show any significant difference on the blood flow parameters in both wild-type and gucy1a1 ± background larvae. In summary, we successfully established a zebrafish platform for investigating sGC-associated pathways and underlying mechanisms in depth. This model system will have further applications, including for potential drug screening experiments. [ABSTRACT FROM AUTHOR]

In this research work, we have investigated the Stokesian flow of a micropolar fluid in a cylindrical tube enclosing an impermeable core coated with porous layer in the presence of magnetic field. The axis of the cylinder is taken along the direction of fluid flow and the uniform magnetic field is applied in the direction perpendicular to the axis of the cylinder. Using appropriate boundary conditions, fluid velocities, microrotational velocities and stresses are evaluated for corresponding fluid flow regions. Expressions for volumetric flow rate through the annulus and the filtration velocity are obtained. Graphs of linear velocities, microrotational velocities and flow rate for various values of different parameters are plotted and discussed. [ABSTRACT FROM AUTHOR]

Under conditions of unilateral occlusion of the ureter, the development of microhemodynamic disorders of the cortical substance of the kidneys was studied both on the damage side and on the contralateral (opposite) side. It has been established that disorders on the side of occlusion depend on the duration of obstruction of the lumen of the ureter, which determines the development of tissue hypoxia and violates trophic renal parenchyma. Dynamically functional disorders of the microvasculature occur at the early (on the 1st, 3rd, and 5th day), and irreversible changes in the renal parenchyma at the later (on the 14th and 30th day) stages of the experiment. The contralateral one responds to turning off the function of one kidney by adaptive restructuring of the microhemocirculatory system, which is manifested by dilatation of microvessels and an increase in the linear velocity of blood flow in them, which ensures its hyperfunction. [ABSTRACT FROM AUTHOR]

Blood platelets are formed by fragmentation of long membrane extensions from bone marrow megakaryocytes in the blood flow. Using lattice-Boltzmann/immersed boundary simulations we propose a biological Rayleigh–Plateau instability as the biophysical mechanism behind this fragmentation process. This instability is akin to the surface tension-induced breakup of a liquid jet but is driven by active cortical processes including actomyosin contractility and microtubule sliding. Our fully three-dimensional simulations highlight the crucial role of actomyosin contractility, which is required to trigger the instability, and illustrate how the wavelength of the instability determines the size of the final platelets. The elasto-hydrodynamic origin of the fragmentation explains the strong acceleration of platelet biogenesis in the presence of an external flow, which we observe in agreement with experiments. Our simulations then allow us to disentangle the influence of specific flow conditions: While a homogeneous flow with uniform velocity leads to the strongest acceleration, a shear flow with a linear velocity gradient can cause fusion events of two developing platelet-sized swellings during fragmentation. A fusion event may lead to the release of larger structures which are observable as preplatelets in experiments. Together, our findings strongly indicate a mainly physical origin of fragmentation and regulation of platelet size in flow-accelerated platelet biogenesis. [ABSTRACT FROM AUTHOR]

A novel approach based on the local entropy generation rate, also known as the second law analysis (SLA), is proposed to compute and visualize the flow resistance in mass transfer through a pipe/channel with a sudden contraction component (SCC) at low Reynolds number (Re) featuring velocity slip. The linear Navier velocity slip boundary condition is implemented using the explicit scheme. At small Reynolds number, i.e., Re ≤ 10.0, the flow resistance coefficient of the SCC, KSCC, is found to be a function of the dimensionless velocity slip length L s l i p * and Re−1, and gradually increase to a constant value at contraction ratio Rarea ≥ 8, reaching a formula K S C C = (0.4454 L s l i p * 3 − 1.894 L s l i p * 2 + 2.917 L s l i p * + 8.909) / R e. Over this range of Re, the equivalent length of the flow resistance is almost independent of Re, while out of this range, the equivalent length increases monotonically with Re. Moreover, the dimensionless drag force work around the SCC is negative and reaches a minimum at a critical L s l i p * . The SLA reveals that the regions affected by the SCC mainly concentrate around the end section of the upstream pipe/channel rather than the initial partition of the downstream section reported in large Re turbulent flow, and this non-dimensional affected upstream length increases with L s l i p * . The fluid physics are further examined using SLA to evaluate the energy loss over the entire domain, decomposed as the viscous dissipation inside the domain and the drag work on the wall boundary. [ABSTRACT FROM AUTHOR]

In the present work, the magnetohydrodynamic flow of a micropolar fluid through the membrane composed of impermeable cylindrical particles coated by porous layer is considered. The flow of a fluid is taken parallel to an axis of cylinder and a uniform magnetic field is applied in transverse direction of the flow. The problem is solved by using the cell model technique for the flow through assemblage of cylindrical particles. The solution of the problem has been obtained by using no‐slip condition, continuity of velocity and stresses at interfaces along with Happle's no‐couple stress condition as the boundary conditions. The expressions for the linear velocity, micro‐rotational velocity, flow rate and hydrodynamic permeability of the membrane are achieved in this work. The obtained solution for velocities is used to plot the graph against various transport parameters such as, Hartmann number, coupling parameter, porosity, scaling parameter etc. The effect of these transport parameters on the flow velocity, micro‐rotational velocity, and the hydrodynamic permeability of the membrane have been presented and discussed in this work. [ABSTRACT FROM AUTHOR]

The effects of linear flow velocity and ion concentration on limiting current density (LCD), an important parameter in the design and operation of electrodialysis (ED) devices, was examined. As the applied voltage increased, reduction rate of the conductivity increased. However, it did not increase beyond a certain limit because of the effect of concentration polarization. The maximum applied potential of synthetic wastewater, prepared with NaCl (2,000 mg/L), was 15.4 V and the LCD was estimated to be 77.9 mA/cm². When the linear flow velocity of the diluate was increased by 1, 2, and 6 cm/s, LCD increased in direct proportion to the increase in electrical conductivity. The relationships between LCD, linear velocity, and ion concentration were established and parameters a and b were experimentally estimated. In contrast, as a result of changing the linear flow velocity of the concentrate by the same levels, there was no significant difference in the rate of reduction in conductivity. LCD measurements using synthetic wastewater containing various ions, including copper and nickel, and plating wastewater showed that the LCD was slightly higher because the ionic charge was higher than NaCl under the same conductivity conditions. Overall, LCD showed a tendency to be proportional to electrical conductivity. [ABSTRACT FROM AUTHOR]

Cathodic electrodeposition of metal ions can be achieved in parallel plate reactors. The reactor duty is enhanced when it is operated under limiting current conditions at the cathode. Such conditions are closely related to the fluid pattern over the entire cathode area. In this work, the theoretical feasibility for the removal of Cu2+ ions in an electrochemical reactor at laboratory level was analyzed as a function of the flow pattern. A commercial computational fluid dynamics code (ANSYS Fluent) was used to describe the hydrodynamic as the electrolyte passes through a laboratory electrochemical reactor (channel reactor: 0.10 m length, 0.05 m width, 0.01 m depth and electrode area 0.005 m² ). The simulation was performed at mean linear inlet flow velocities between 0.011 and 0.056 m s-1. The flow predictions show how the development of the flow pattern is affected by both the manifold and the flow velocity. It was possible to estimate that the fluid flow was developed over the 90, 80 and 70% of the cathode area when the mean linear inlet flow were 0.011, 0.033 and 0.056 m s-1, respectively. Under these hydrodynamic conditions, the electrochemical reactor performance will be maximized because it was expected to have a uniform limiting current density over the cathode area according to the estimated percentages mentioned before. In the same range of linear flow velocities, a uniform limiting current for cathodic Cu2+ reduction was experimentally obtained, as expected. [ABSTRACT FROM AUTHOR]

This paper deals with synchronised influences of hydromechanical and hydrochemical parameters on the formation of solid deposits in geothermal and other waters, which compose complex heterogeneous and micro-heterogeneous liquid-solid systems. The constituents of these waters in ionic, colloidal and micro-heterogeneous suspended liquid-solid states are responsible for the creation of carbonates, sulphates and other solid matters. In these processes, one cannot eliminate the influence of hydromechanical parameters with flow velocity and water flow criteria (laminar or turbulent flow) as vital factors. Experiments were conducted on the laboratory pilot installation with glass pipes of 2, 4, 6, 8 and 10 mm in diameter, respectively, and the flow was monitored by using a digital peristaltic pump with the flow rate of 2 ml/min to 5000 ml/min. The paper studies the impact of the linear flow velocity on the relative decrease of the initial water hardness in geothermal waters of Sijarinska Banja spa, Niška Banja spa and the estuary water of Medijana, Niš. From the obtained dependences, according to the linear regression model, for each diameter, critical values for linear velocities were determined, as an important parameter for the understanding of the synergism of the hydromechanical and hydrochemical parameters were determined. [ABSTRACT FROM AUTHOR]

• A scaling analysis for the hydraulic behavior in reactor pressure vessel is conducted. • Scaling criteria for the reactor hydraulic test are obtained. • Important phenomena with high ranking in the hydraulic test are analyzed. • Some valuable suggestions for the future test are listed. The hydraulic behavior of coolant flow in reactor pressure vessel plays an important role in the thermal hydraulic and safety analysis of nuclear reactor system. Conventional reactor hydraulic tests were carried out by linearly down scaled facilities without tough physical principle. In this work, a scaling analysis in control volume scale for the hydraulic behavior in reactor pressure vessel is conducted to develop a theoretical basis for the down scaled hydraulic test. The mass, axial and lateral momentum conservation in reactor core is analyzed. Important scaling criteria for the reactor hydraulic test are obtained. It is found that the flow velocity should be reduced to promise the similarity of all scaling criteria. The identical velocity simulation with linear scaling method could results a distortion of about 16% to the lateral mixing criterion. This work is helpful to establish the theoretical basis for the hydraulic experiment and numerical research. [ABSTRACT FROM AUTHOR]

Due to the extensive range of ionic liquids (ILs) used in industry, an efficient recovery method is needed. In this study, the effectiveness of a simultaneous concentration and recovery method was investigated for 1-ethyl-3-methylimidazolium chloride ([Emim]Cl), an IL that was recovered using electrodialysis (ED). The optimal operational parameters for electrodialytic recovery were determined empirically. The variables that were investigated included the concentration of IL, applied voltage, linear flow velocity and the diluate-to-concentrate volume ratio. The recovery of [Emim]Cl, the concentration degree, the [Emim]Cl flux across membranes, the current efficiency, as well as the energy consumption were determined. The results of the experiments confirmed that [Emim]Cl concentration and recovery can be achieved using ED. The highest ED efficiency was obtained when a 2 V electric potential per one membrane pair was applied, using a 2 cm/s linear flow velocity, and by adjusting to 0.2 M IL in the feed solution. By using ED, a 2.35-fold concentration of [Emim]Cl with a recovery of 90.4% could be achieved when the diluate-to-concentrate volume ratio was 2. On the other hand, a 3.35-fold concentration of [Emim]Cl with a recovery of 81.7% could be obtained when the diluate-to-concentrate volume ratio was increased to 5. [ABSTRACT FROM AUTHOR]

Extracting lithium from brines is challenging due to the high Mg2+/Li+ ratio and low Li+ concentration. In this paper, a selective electrodialysis process (S-ED) with feed and bleed mode was developed to extract Li+ continuously from brines. Take the system performance including the recovery ratio of Li+ (R Li), leakage ratio of Mg2+ (L Mg), migration rate (M r), specific energy consumption (E SEC), current efficiency (η) and separation coefficient of Li+ and Mg2+ (F Li-Mg) as evaluation parameters, the typical factors such as applied voltage, supplementary feed flow rate, and linear flow velocity were investigated. In addition, the Li+ extraction parameters of different feed solution species in the S-ED process were compared under optimization operating conditions and Li 2 CO 3 was obtained from Li-rich solution by precipitation reaction. The results showed that the increase of voltage could promote R Li , but the excessive voltage caused a decrease in F Li-Mg. The increase of the linear flow velocity could increase M r but hardly affected F Li-Mg and E SEC. The increase in the supplementary feed flow increased F Li-Mg. For different feeding solutions, it was found that extracting Li+ from bittern had good economic value and high purity Li 2 CO 3 was obtained after S-ED. Compared with the traditional process, the S-ED process with the "feed and bleed" mode proposed in this article has the advantages of simple operation, continuity, and environmental friendliness. It is a promising technology that can continuously enrich Li+ from brines. SYNOPSIS Selective-electrodialysis(S-ED) with feed and bleed mode was proposed to prepare battery-grade lithium carbonate continuously from high Mg2+/Li+ brines. [Display omitted] • A selective electrodialysis process (S-ED) with feed and bleed mode was developed. • The continuous S-ED can extract Li+ continuously from high Mg2+/Li+ ratio brines. • The continuous S-ED process has better industrialization potential than batch S-ED. • Typical factors that affect the continuous S-ED process were investigated. • Extracting Li+ from bittern by continuous S-ED process had good economic value. [ABSTRACT FROM AUTHOR]

Effect of flow velocity and cell-pair thickness in electrodialysis (ED) is studied. The production cost includes pump energy, while the size of the system is considered as an output variable. The performance of ED system depends on three categories of process parameters namely water quality data, stack configuration and flow characteristic inside the stack. The design of ED system is complex due to interrelation among the system variables so the design calculation chronology steps are developed with flow-chart for the fix feed salinity of groundwater and salt removal rate. The effect of recovery ratio on capital and energy cost is studied and found unidirectional. Sparingly soluble salt present in feed decides the upper limit and obtained 70–75% recovery rate based on the feedwater quality. The optimum value of the linear flow velocity and cell-pair thickness can be obtained by the trade-off among capital cost, stack energy cost and pumping energy cost. Simultaneous effect of both the variable on minimizing the total cost gives the narrow working range of flow velocity 15–17 cm/s and 0.4–0.8 mm thickness. The minimum production cost of 0.08 USD/m3 is obtained at 16 cm/s velocity and 0.5 mm thickness. [Display omitted] • Designing electrodialysis pilot scale unit by setting parametric chronology flow chart. • Recovery ratio of 75% can be obtained for brackish groundwater at neutral pH level. • Product cost minimization by varying flow velocity and cell-pair thickness simultaneously. • Optimum flow velocity and cell-pair thickness is found 15–17 cm/s and 0.4–0.8 mm. [ABSTRACT FROM AUTHOR]

A comparative analysis of estimates of the formation time for intrusions observed under absolutely stable thermohaline stratification in the upper layer of the Deep Polar Water (DPW) is presented based on two different approaches: 1) 2D instability model of the baroclinic front accounting for differential mixing [1], 2) 3D instability model of the geostrophic flow with a linear vertical velocity shear accounting for diffusion of buoyancy and momentum [2]. The instability of the baroclinic front described by model 1 is a monotonic instability. The unstable modes are presented by periodic trigonometric functions; they have no along-front slope. According to model 2, the phase velocity of unstable disturbances depends on the along-front wavenumber k, and the instability is observed in a wide range of horizontal scales: there are unstable long-wave modes with a phase velocity exceeding the maximum value of flow velocity (see [3, 4] for detail), unstable modes on the scales of the Rossby radius, and short-wave perturbations with scales significantly smaller than the Rossby radius (submesoscale structures).For weak geostrophic currents with velocity of about 1 cm/s, which is typical for the upper layer of the DPW, and for typical hydrological parameters of the observed fronts, the formation time of intrusions was found to be about several years for model 1 and about 50-100 days on the scales of the Rossby radius for model 2. A discussion on the description of DPW intrusions based on these two approaches is presented.This research was funded by the state assignment of IO RAS, theme No 0149-2019-0003.Literature1. Kuzmina N.P., Zhurbas N.V., Emelianov M.V., Pyzhevich M.L. Application of interleaving models for description of intrusive layering at the fronts of Deep polar water in the Eurasian Basin (Arctic) // Oceanology. 2014. Vol. 54. No. 5. PP. 557–566. (Engl).2. Kuzmina N.P., Skorokhodov S.L., Zhurbas N.V., Lyzhkov D.A. Description of the disturbances of oceanic geostrophic currents with linear vertical velocity shear taking into account friction and diffusion of density // 2019. Fizika Atmosfery i okeana. In press.3. Kuzmina N.P. Generation of large-scale intrusions at baroclinic fronts: an analytical consideration with a reference to the Arctic Ocean // Ocean Science. 2016. 12(6). P. 1269–1277. doi: 10.5194/os-12-1269-2016.4. Kuzmina N.P., Skorokhodov S.L., Zhurbas N.V., Lyzhkov D.A. Instability of a Geostrophic Current with Linear Vertical velocity shear at scales of interleaving // Fizika Atmosfery i okeana. 2018. 54(1). P. 54–63. [ABSTRACT FROM AUTHOR]