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Multi-layer membrane filtration is a widely used technology for separating and purifying different components of a liquid mixture. This technique involves passing the liquid mixture through a series of membranes with decreasing pore sizes, which allows for the separation of different components according to their molecular size. This study investigates the filtration process of a fluid through a two-dimensional porous medium designed for seawater desalination. The focus is on understanding the impact of various parameters such as the coefficient of friction, velocity, and the number of layers on filtration efficiency. The results reveal that the number of layers plays a crucial role in desalination, with an increase in layers leading to enhanced filtration quality, following a power law relationship. The study explores the influence of the coefficient of friction on filtration performance, emphasizing its significant effect on the number of particles filtered over time. Additionally, the role of the initial velocity in filtration efficiency is examined, showing distinct effects at both high and low velocities. Biofouling is identified as a factor influencing filtration, with an initial increase in filtered particles followed by a decline due to particle accumulation in pores. [ABSTRACT FROM AUTHOR]

In horizontal well operations, the prevalence of stuck pipe incidents is largely attributed to inadequate hole cleaning, underscoring the critical need for a thorough understanding of this process to mitigate non-productive time and financial losses. Increasing fluid velocity, the major drilling parameter of hole cleaning, diminishes the formation of cuttings beds in a wellbore. This study primarily centered on the mechanical displacement and removal of solid particles, employing advanced image processing techniques to elucidate the dynamic behavior of solid particles in deviated wellbores. The core objective of this study was to experimentally scrutinize the effects of a downhole clamp-on tool on fluid velocity to improve hole cleaning practices. To address this challenge, a customized flow loop was designed and constructed to accurately replicate the conditions encountered in horizontal wells. Pure water was used to demonstrate the effects of the clamp-on tool on cuttings transport for lightweight drilling fluid conditions. Strategically deployed, the clamp-on tool played a pivotal role in agitating cuttings, mitigating their accumulation at the bottom of the borehole. The tool's agitation mechanism noticeably improved cuttings removal by increasing velocity, extending the perturbation of cuttings transport in the tool's downstream flow, and reducing bedding formation. At lower flow rates, the tool led to an over fourfold increase in average particle velocity within the tool and a twofold increase after the tool. Our results demonstrate the substantial potential of mechanical assistance to address hole cleaning challenges and significantly advance horizontal well operations. [ABSTRACT FROM AUTHOR]

Regarding the low machining efficiency and poor surface quality in micro-electrical discharge machining (μ-EDM) of large depth-to-diameter ratio micro-holes, this paper focuses on ultrasonic vibration–assisted multi-objective optimization in μ-EDM to achieve high material removal rate (MRR) and low tool wear rate (TWR). In this work, second-order quadratic models were developed for MRR and TWR, considering the peak voltage (U p), peak current (I p), pulse width (Width), frequency (Freq.), ultrasonic amplitude (UA), and rotation speed (Rot.) as the machining parameters, using the Plackett–Burman design and Box–Behnken design. The developed models were used for multi-objective optimization by desirability function approach to determine the optimum machining parameters. The optimized parameters were processed for micro-holes, and it was found that the surface quality of the micro-holes was significantly improved. [ABSTRACT FROM AUTHOR]

In order to effectively prevent fire accidents and improve fire management capability, this paper describes the independent designs and builds of an experimental low-cost particle image velocimetry platform for a propane jet combustion flame using traditional mutual correlation theory. The particle image velocimetry (PIV) algorithm is written based on MATLAB software, allowing it to realise image preprocessing, multi-level grid window deformation inter-correlation calculations, and other functions. Fluid flow velocity and vorticity are used as entry points to study the flame combustion mechanism. The air flow field and vorticity above the propane jet flame are analysed. The results show that, from the level of fluid flow velocity, the maximum fluid flow velocity in the test area does not exceed 0.23 m/s, and the maximum transverse fluid flow velocity is close to 0.15 m/s. Additionally, the longitudinal fluid flow velocity is opposite the upper and lower portions of the longitudinal flow velocity, and there is a swirling phenomenon in the propane flame jet. From the vorticity level, the closer to the centre of the jet in the vortex plane, the faster the air flow speed, and simultaneously, in the upper and lower parts of the vortex, the air flow travels in the opposite direction and is of equal size. The particle image velocimetry platform that was independently designed in this study can efficiently characterise the dynamic flow field and the flow characteristics of complex combustion chambers, simultaneously ensuring high efficiency and reducing research costs. It provides a measurement method and experimental basis for the development of fire extinguishing equipment and numerical simulation, while also helping us to carry out a series of subsequent studies on fire extinguishing mechanisms. [ABSTRACT FROM AUTHOR]

To research the dynamics of the cavitation bubble under the interaction of particle clusters, the bubble morphological evolutionary characteristics near three equal-sized spherical particles are theoretically explored in the present study based on the Weiss theorem and the velocity potential superposition theory. The three particles are arranged symmetrically, and the fluid velocity field near the three particles and the cavitation bubble is obtained. Moreover, the effects of the bubble-particle distance and the maximum radius of the cavitation bubble on the fluid velocity are investigated, and the contribution mechanisms of the fluid velocity field constituents are compared. The analysis has found that: (1) The fluid velocity between the bubble and the particle is lower than that at the other locations in both the growth and collapse phases, thus the bubble cannot always maintain a standard spherical shape. (2) The bubble-particle distance and the maximum radius of the cavitation bubble are the key parameters affecting the circumferential inhomogeneity of the radial velocity of the fluid around the bubble. The larger the maximum radius or the smaller the bubble-particle distance is, the more visible the non-circularity of the bubble morphology. (3) The image bubbles and the linear sinks contribute oppositely to the fluid velocity field, and the presence of the image bubble reduces the fluid velocity. In the low velocity region, the image bubble is the main mechanism contributing to the effect of the particle on the fluid velocity. [ABSTRACT FROM AUTHOR]

AbstractThis paper has focused on the study of flow characteristics of a steady conductive fluid through a circular pipe in the presence of an applied transverse uniform magnetic field. A numerical simulation of the fluid flow was performed using a multi-physics computational tool. The radial velocity distribution due to the effect of the tangential component of induced magnetic flux density and electric fields at various axial positions is examined in metallic and non-metallic surfaces of the circular pipe. This simulation study helps to analyse the effect of drag force on the variation in axial velocity close to the metallic and non-metallic walls. The induced electric potential is directed along the normal to the Laplacian tangential surface of the pipe. In addition to that, sigmoidal-shaped field profiles are observed when the fluid flow crosses from the upstream to downstream of the magnet edge and vice versa along the axial length of the circular pipe. Simultaneously, it is observed that the average velocity of the fluid flow decreases for a laminar and increases for turbulent Reynolds number. Streamline plots pertinent flow variable such as flow velocity are presented for non-conducting and conducting walls.

The method of Spectral collocation is used to analyze the flowing Nano fluid layer in contact with a stretching surface for comprehensive information and thus to have its utility in industrial activities like the production of glass fibers, petroleum refining, hot rolling of metals, metal spinning etc. The spectral collocation model incorporates thermophoresis and Brownian motion phenomena to describe the fluid flow, fluid concentration and temperature profiles. A similarity solution has been presented for the governing equations of fluid momentum, concentration and temperature. The computational results are the function of Prandtl number (Pr), Lewis number (Le), thermophoresis and Brownian motion phenomena. The engineering quantities like thermophoresis parameter (Nt), Brownian motion parameter (Nb), buoyancy-ratio parameter (Nr) and reduced Nusselt number (Nu) and reduced Sherwood number (Sh) have tabulated corresponding to Prandtl number (Pr) and Lewis number (Le). The results of the current study thrown light on fluid velocity and heat transfer rates in the boundary layer. The numerous industrial products and manufacturing processes of superior quality can be exercised with the current studies. [ABSTRACT FROM AUTHOR]

Accurate and real-time measurement of fluid flow velocity is crucial in various industrial processes, especially when dealing with multiple phase fluids. Traditional flow measurement methods often struggle to accurately quantify the velocity of complex multiphase flows within pipes. This challenge necessitates the exploration of innovative techniques capable of providing reliable measurements. This paper proposes the utilization of Electrical Capacitance Tomography (ECT) as a promising approach for measuring the velocity of multiple phase fluids in pipes. The ECT technique involves the non-intrusive imaging of the electrical capacitance distribution within the pipe. By utilizing an array of electrodes placed around the pipe circumference, the capacitance distribution can be reconstructed, offering insight into the fluid flow patterns. By analyzing the temporal changes in the capacitance distribution, the velocity of different phases within the pipe can be estimated. To achieve accurate velocity measurements, an ECT system needs to account for the complexities introduced by multiphase flows. Various image reconstruction algorithms, such as linear back-projection and iterative algorithms like Gauss-Newton and Levenberg-Marquardt, are employed to reconstruct the capacitance distribution. Additionally, advanced signal processing techniques, such as cross-correlation analysis and time-difference methods, are used to extract velocity information from the reconstructed images. This paper presents an experimental investigation of measuring the velocity of multiple-phase fluids in pipes using the ECT technique. The study aims to address the challenges associated with different flow regimes, fluid properties, and pipe geometries by exploring advancements in electrode design, system calibration, and data processing techniques to enhance the accuracy and robustness of ECT-based velocity measurements. [ABSTRACT FROM AUTHOR]

The desalination process using membrane distillation (MD) has recently attracted wide attention in the last few years around the world. Especially, membranes that have an asymmetric geometry, for their performance to filtrate the salt water and the high salt rejection. In this paper, the Langevin dynamics model was adopted as a simulation method to investigate the transport of salt water through the sloping membrane under a pressure drop. The surface of the used membrane is considered as a hydrophilic sloping surface. Thus, the pressure drop effect on the fluid flux was observed, which leads to attracting the salt water into pores that are randomly distributed. The influence of deposition and accumulation of the ions into pores, the incline angle of the membrane surface, and the thickness of the formed layer on the surface were investigated. In addition, the impact of biofouling is caused by the accumulation and the variation of the fluid velocity as a function of pressure drop values. The obtained results show that the relationship between the fluid velocity and the pressing force is a power law. Moreover, the increase in fluid flow velocity in the porous medium is severe in the earlier time regime, but it becomes almost constant in the second regime. However, the time desalination process increases linearly with the pressure drop. Moreover, the accumulation and deposition of ions into the pores cause a decrease in the water flow through the pores resulting in a higher pressure drop in the less inclined direction. Finally, the influence of deposition and accumulation of the salt phase into the pores on the membrane performance was remarked, resulting in a high desalination rate. The obtained results explain the salt water behavior through a porous membrane, which provides ideas for making a high membrane performance. [ABSTRACT FROM AUTHOR]

The objective of the present study was to make a theoretical study based on a CFD analysis for a conventional radial clarifier. The parameters of the Computational Fluid Dynamics analysis were set in the Ansys software, and after running the simulation, the values for fluid velocity, turbulence intensity and Reynolds number were obtained. Thus, it was obtained a fluid velocity of 0.103 m/s, a turbulence intensity of 3.82十0-% and a Reynolds number of 14.7. This work can help researchers in the field, mainly, but also radial clarifier manufacturers to optimise the process. [ABSTRACT FROM AUTHOR]

In order to effectively prevent fire accidents and improve fire management capability, this paper describes the independent designs and builds of an experimental low-cost particle image velocimetry platform for a propane jet combustion flame using traditional mutual correlation theory. The particle image velocimetry (PIV) algorithm is written based on MATLAB software, allowing it to realise image preprocessing, multi-level grid window deformation inter-correlation calculations, and other functions. Fluid flow velocity and vorticity are used as entry points to study the flame combustion mechanism. The air flow field and vorticity above the propane jet flame are analysed. The results show that, from the level of fluid flow velocity, the maximum fluid flow velocity in the test area does not exceed 0.23 m/s, and the maximum transverse fluid flow velocity is close to 0.15 m/s. Additionally, the longitudinal fluid flow velocity is opposite the upper and lower portions of the longitudinal flow velocity, and there is a swirling phenomenon in the propane flame jet. From the vorticity level, the closer to the centre of the jet in the vortex plane, the faster the air flow speed, and simultaneously, in the upper and lower parts of the vortex, the air flow travels in the opposite direction and is of equal size. The particle image velocimetry platform that was independently designed in this study can efficiently characterise the dynamic flow field and the flow characteristics of complex combustion chambers, simultaneously ensuring high efficiency and reducing research costs. It provides a measurement method and experimental basis for the development of fire extinguishing equipment and numerical simulation, while also helping us to carry out a series of subsequent studies on fire extinguishing mechanisms.

This paper has focused on the study of flow characteristics of a steady conductive fluid through a circular pipe in the presence of an applied transverse uniform magnetic field. A numerical simulation of the fluid flow was performed using a multiphysics computational tool. The radial velocity distribution due to the effect of the tangential component of induced magnetic flux density and electric fields at various axial positions is examined in metallic and non-metallic surfaces of the circular pipe. This simulation study helps to analyse the effect of drag force on the variation in axial velocity close to the metallic and non-metallic walls. The induced electric potential is directed along the normal to the Laplacian tangential surface of the pipe. In addition to that, sigmoidalshaped field profiles are observed when the fluid flow crosses from the upstream to downstream of the magnet edge and vice versa along the axial length of the circular pipe. Simultaneously, it is observed that the average velocity of the fluid flow decreases for a laminar and increases for turbulent Reynolds number. Streamline plots pertinent flow variable such as flow velocity are presented for non-conducting and conducting walls. [ABSTRACT FROM AUTHOR]

To optimize production strategy, monitor reservoir performance, and maximize economic recovery of oil and gas fields, it is very important to accurately measure the separate phase flow of each fluid in multiphase flow. Due to the complexity of multiphase flow, the traditional method of measuring the flow per phase is challenging. The Spinner Array Tool (SAT) and equidistant area-weighted average method are used to predict the average fluid velocity of oil-water two-phase flow in horizontal wells. The slippage model is used to calculate the total volume flow of the fluid and the volume flow of each fluid. We collected mini-spinner sensing data in a Spinner Array Tool (SAT) for the oil-water two-phase and used the response characteristics of the single-phase fluid as reference data before mixing. The experimental results show that the isometric area-weighted average method can better process the sensor data of the Spinner Array Tool (SAT), and obtain better phase separation flow accuracy under different flow conditions. The predicted oil flow is in good agreement with the measured oil flow. The results show that it is feasible to infer the prediction results of the fractional flowrate from the prediction results of the average fluid velocity in the actual production logging. • The equidistant area weighted average method was used to predict the flow rate of oil-water two-phase in horizontal wells. • Spinner Array Tool (SAT) was used to collect sensing data of oil-water two-phase mini-spinners. • The predicted oil flow rate is in good agreement with the measured oil flow. [ABSTRACT FROM AUTHOR]

Ventilation cooling design is one of the key technologies during the design of large hydrogenerator. With the increase of hydrogenerator capacity, the overheating problem of rotor region become more and more serious. In this paper, a 250 MW hydrogenerator is analyzed. The transient electromagnetic field of the hydrogenerator is calculated. The losses (heat sources) of rotor components in the rotor region of the hydrogenerator are determined. Three-dimensional fluid and thermal coupled mathematic model of the hydrogenerator rotor region is established. The rotor rotation of the hydrogenerator is considered. The distribution of complex fluid velocity in the rotor region is calculated using the finite volume method. The influence of fluid velocity in the different directions on the temperature of the rotor excitation winding is studied under the different flow rates in the rotor region. The surface heat-transfer coefficient distribution of the rotor components is determined. The temperature distribution of the rotor excitation winding, rotor pole body, rotor press plate, rotor damping bar, and rotor end ring is obtained. The calculated temperature results match well with test values. These provide an important reference for the rotor structural design and optimization of larger hydrogenerator.

In this research, the vibration and frequency of single-walled carbon nanotubes (SWCNTs) with conveyance a fluid flow are assessed analytically. The nanotube is imbedded in a Pasternak foundation and the nonlocal beam model is utilized to study on flow-induced vibration of the SWCNT. The differential transform method and variation iteration scheme have been employed to solve the nonlinear differential equation of the problem. The validity of proposed approaches is evaluated by comparing with numerical findings obtained using Keller Box method (KBM). The effects of main parameters including velocity of flow, nonlinear amplitude, nonlocal parameter as well as axial tensions on variation of the SWCNT's frequency are examined. The outcomes indicate that increment of the nonlocal parameter leads to enhancement in variation of frequency. Also, the frequency variation of the SWCNT increases by elevating the axial tension. [ABSTRACT FROM AUTHOR]

According to the flow calculation, the basic structure of the sprinkler pipe of the integrated suction and drainage fertilizer truck was designed. Based on the 3D CAD / CAE Software SolidWorks / flow simulation platform, the structural models of three kinds of sprinkler pipes with different layout forms of outlet pipes were established, and the fluid analysis was carried out. According to the distribution of pressure, velocity and flow trace number in the tube, the optimal structure was obtained. [ABSTRACT FROM AUTHOR]

Purpose: The aim of the present study was to visualize and compare the cavitation effect and fluid dynamics induced by photon-induced photoacoustic streaming (PIPS) using sodium hypochlorite (NaOCl) with different concentrations as irrigant. Methods: Forty artificial root canals were prepared using MTWO Niti file up to size #25/.06. The canals were randomly divided into four groups (n = 10/group). High-speed camera was used to visualize and compare the cavitation effect induced by PIPS in the artificial root canals containing saline or NaOCl. Fluid velocity and Reynolds number of saline, 1%-, 2.5%- and 5.25% NaOCl irrigants induced by PIPS in the apical region were calculated using TEMA 2D software while the fluid motions were recorded. Results: Visualization profile revealed that NaOCl presented a stronger cavitation effect and fluid dynamics than saline during PIPS activation. In the apical region, 1% NaOCl group presented the highest average velocity of 3.868 m/s, followed by 2.5% NaOCl group (3.685 m/s), 5.25% NaOCl group (2.353 m/s) and saline group (1.268 m/s), corresponding to Reynolds number of 1653.173, 1572.196, 995.503 and 477.692. Statistically higher fluid velocity was calculated in 1% and 2.5% NaOCl groups compared to saline group, respectively (p < 0.05). Conclusions: The application of NaOCl and its concentration significantly influence the cavitation effect and fluid dynamics during PIPS activation. 1% and 2.5% NaOCl groups presented a more violent fluid motion in the apical region when activated by PIPS. [ABSTRACT FROM AUTHOR]

Many researchers numerically investigated U-tube underground heat exchanger using a two-dimensional simplified pipe. However, a simplified model results in large errors compared to the data from construction sites. This research is carried out using a three-dimensional full-size model. A model validation is conducted by comparing with experimental data in summer. This article investigates the effects of fluid velocity and buried depth on the heat exchange rate in a vertical U-tube underground heat exchanger based on fluid–structure coupled simulations. Compared with the results at a flow rate of 0.4 m/s, the results of this research show that the heat transfer per buried depth at 1.0 m/s increases by 123.34%. With the increase of the buried depth from 80 to 140 m, the heat transfer per unit depth decreases by 9.72%.

Interstitial fluid pressure, interstitial fluid velocity and related parameters are of great clinical significance for cancer diagnosis, prognosis and treatment. A limited number of non-invasive techniques can be used to estimate these mechanopathological parameters in cancers in vivo. In this study, we designed and tested new ultrasound poroelastography methods capable of estimating the magnitude and spatial distribution of fluid pressure, fluid velocity and fluid flow inside tumors under external compression. We theoretically proved that fluid pressure, velocity and flow estimated using poroelastography from a tumor under creep compression are directly related to the underlying interstitial fluid pressure, interstitial fluid velocity and fluid flow, respectively, differing only in peak values. Furthermore, by knowledge of the spatial distribution of the fluid pressure estimated using poroelastography, it is possible to derive: the parameter $\alpha $ , which quantifies the spatial distribution of the interstitial fluid pressure, the vascular permeability to interstitial permeability ratio and the peak interstitial fluid pressure to effective vascular pressure ratio in the tumor. Our techniques were validated using finite element and ultrasound simulations for a variety of simulated phantoms. Excellent qualitative agreement was found between the fluid pressure and velocity obtained using the finite element models and the corresponding fluid pressure and fluid velocity obtained using the proposed models. The estimated parameter $\alpha $ was found to differ from the corresponding theoretical value by less than 10%. Experiments on a human breast cancer animal model were used as proof-of-principle of the feasibility of the proposed methods in vivo.

The self-designed flow system was used to study the flow corrosion of X100 pipeline steel in simulated formation water environment by electrochemical measurements as well as computational fluid dynamics (CFD) simulation. The effects of fluid flow velocity and fluid impact angle on X100 steel were determined. When the fluid flow velocity changes between 0.5–2.0 m/s, X100 steel is controlled by activation, and as the flow velocity increases, the self-corrosion current Icorr increases, the corrosion rate increases; when the impact angle increases from 30° to 90°, the self-corrosion current Icorr decreases and the corrosion rate decreases. CFD simulations show that at different flow velocities and impact angles, the velocity field distribution on electrode surface is different. At the minimum impact angle of 30°, the electrode area has the largest flow velocity and shear stress, therefore the corrosion damage is the most serious.

Abstract The identification process of different lithologies, hydrocarbons, and water-saturated zones in oil and gas industries involves petrophysical studies that are carried out by geoscientists using different software packages. This study aims to propose a method by integrating mean cluster analysis and well logs to identify dominant lithologies, pore fluids, and fluids contact. For this purpose, initially, K-mean cluster analysis is applied to density log and P-wave velocity data of three wells in order to group them into different clusters. Based on centroids of each cluster, different lithologies have been identified. The density log equation has been utilized to compute the porosity of each cluster, and the mean of each density log cluster is used as matrix density. Next, sonic log equation has been inverted to compute the fluid velocity and the mean of each P-wave velocity cluster is used as matrix velocity. For the fluid density, sonic and density log equations are jointly inverted to compute the fluid velocity of each cluster. The fluid bulk modulus and acoustic impedance are computed using fluid density and velocity. Based on the results of K-mean cluster analysis, different lithologies (shale, sandstone, and limestone) have been recognized successfully. In well-1, hydrocarbon and water-saturated zones are successfully identified and fluids contact has been established in the zone of interest. However, well-2 and well-3 did not show any indications of the presence of hydrocarbon in the respective zones.

This study investigated how air bubbles in media affect tablet dissolution in a flow-through cell system (USP 4) using disintegrating (USP prednisone) and non-disintegrating (USP salicylic acid) tablets. Cell hydrodynamics were studied using particle image velocimetry (PIV) and computational fluid dynamics (CFD). The PIV analysis showed periodic changes in the local flow corresponding to the discharge and suction of the pump cycles. The absence of prior deaeration induced small air bubbles in the media and lower maximum flow during the cycle, explaining the slower dissolution of the USP salicylic acid tablets. Bubbles, occurring during the USP prednisone tablets study, induced the transition of floating disintegrated particles towards the cell outlet, whereas the particles precipitated to form a white layer on the glass beads used in the study with prior deaeration. CFD analysis showed local flow variation in multiple positions of small (ID 12 mm) and large (ID 22.6 mm) cells, explaining the different rates of dissolution of prednisone tablet particles depending on their distribution. These results emphasize the importance of prior deaeration in dissolution studies using a flow-through system. Bubbles in the flow-through cell system affected tablet dissolution by reducing the area in contact with the media (wettability), lowering the maximum instantaneous flow (pressure buffering), and altering the position of disintegrated particles in the cell. [ABSTRACT FROM AUTHOR]

Wave dispersion response of a fluid-carrying piezoelectric nanotube is studied in this paper utilizing an improved model for piezoelectric materials which capture a new effect known as flexoelectricity in conjunction with the surface elasticity. For this aim, a higher order shear deformation theory is employed to model the problem. Furthermore, strain gradient effect as well as nonlocal effect is taken into consideration throughout using the nonlocal strain gradient theory (NSGT). Surface elasticity is also considered to make an accurate size-dependent formulation. Additionally, a non-compressible and non-viscous fluid is taken into consideration to model the flow effect. The wave propagation solution is then implemented to the governing equations obtained by Hamiltonian’s approach. The phase velocity and group velocity of the nanotube is determined for three wave modes (i.e. shear, longitudinal and bending waves) to study the influence of various involved factors including strain gradient, nonlocality, flexoelectricity and surface elasticity and flow velocity on the wave dispersion curves. Results reveal a considerable effect of the flexoelectric phenomenon on the wave propagation properties especially at a specific domain of the wave number. The size-dependency of this effect is disclosed. Overall, it is found that the flexoelectricity exhibits a substantial influence on wave dispersion properties of the smart fluid-conveying systems. Hence, such size-dependent effect should be considered to achieve exact and accurate knowledge on wave propagation characteristics of the system. [ABSTRACT FROM AUTHOR]

During micro-scale tracer flow in porous media, the permeability and fluid velocity significantly affect the fluid dispersion properties of the media. However, the relationships between the dispersion coefficient, permeability, and fluid velocity in core samples are still not clearly understood. Two sets of experiments were designed to study the effects of tracer fluid flow velocity and porous medium permeability on the dispersion phenomenon in a core environment, using natural and sand-filled cores, respectively. From experimental data-fitting by a mathematical model, the relationship between the dispersion coefficient, flow velocity, and permeability was identified, allowing the analysis of the underlying mechanism behind this phenomenon. The results show that a higher volumetric flow rate and lower permeability cause a delay in the tracer breakthrough time and an increase in the dispersion coefficient. The core experimental results show that the dispersion coefficient is negatively correlated with the permeability and positively correlated with the superficial velocity. The corresponding regression equations indicate linear relations between the dispersion coefficient, core permeability, and fluid velocity, resulting from the micron scale of grain diameters in cores. The combination of high velocity and low permeability yields a large dispersion coefficient. The effects of latitudinal dispersion in porous media cannot be ignored in low-permeability cores or formations. These findings can help to improve the understanding of tracer flow in porous media, the design of injection parameters, and the interpretation of tracer concentration distribution in inter-well tracer tests. [ABSTRACT FROM AUTHOR]

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The nucleus pulposus (NP) in the intervertebral disk (IVD) depends on diffusive fluid transport for nutrients through the cartilage endplate (CEP). Disruption in fluid exchange of the NP is considered a cause of IVD degeneration. Furthermore, CEP calcification and sclerosis are hypothesized to restrict fluid flow between the NP and CEP by decreasing permeability and porosity of the CEP matrix. We performed a finite element analysis of an L3–L4 lumbar functional spine unit with poro-elastic constitutive equations. The aim of the study was to predict changes in the solid and fluid parameters of the IVD and CEP under structural changes in CEP. A compressive load of 500 N was applied followed by a 10 Nm moment in extension, flexion, lateral bending, and axial rotation to the L3–L4 model with fully saturated IVD, CEP, and cancellous bone. A healthy case of L3–L4 physiology was then compared to two cases of CEP sclerosis: a calcified cartilage endplate and a fluid constricted sclerotic cartilage endplate. Predicted NP fluid velocity increased for the calcified CEP and decreased for the calcified + less permeable CEP. Decreased NP fluid velocity was prominent in the axial direction through the CEP due to a less permeable path available for fluid flux. Fluid pressure and maximum principal stress in the NP were predicted to increase in both cases of CEP sclerosis compared to the healthy case. The porous medium predictions of this analysis agree with the hypothesis that CEP sclerosis decreases fluid flow out of the NP, builds up fluid pressure in the NP, and increases the stress concentrations in the NP solid matrix. [ABSTRACT FROM AUTHOR]

It is well known that transport of nutrients and wastes as solute in bone fluid plays an important role in bone remodeling and damage healing. This work presents a chemo-poroelastic model for fluid and solute transport in the lacunar-canalicular network of an osteonal cortical bone under cyclic axial mechanical loading or vascular pressure. Analytical solutions are obtained for the pore fluid pressure, and fluid and solute velocities. Numerical results for fluid and calcium transport indicate that under a cyclic stress of 20 MPa, the magnitudes of the fluid and calcium velocities increase with an increase in the loading frequency for the frequency range considered (≤ 3 Hz) and peak at the inner boundary. The peak magnitude of calcium velocity reaches 18.9 μm/s for an osteon with a permeability of 1.5 × 10−19 m2 under a 3 Hz loading frequency. The magnitude of calcium velocity under a vascular pressure of 50 mmHg is found to be two orders of magnitude smaller than that under the mechanical load. These results have the potential to be important in understanding fundamental aspects of cortical bone remodeling as transport characteristics of calcium and other nutrients at the osteon scale influence bone metabolism. [ABSTRACT FROM AUTHOR]

This study analyzes the velocity and pressure incurred by protruding shapes installed within the inlet part of a pressurized membrane module during operation to determine the fluid flow distribution. In this paper, to find the flow distribution within a module, it investigates the velocity and pressure values at cross-sectional and outlet planes, and 9 sections classified on outlet plane using computational fluid dynamics. From the Reynolds number (Re), the fluid flow was estimated to be turbulent when the Re exceeded 4,000. In the vertical cross-sectional plane, shape 4 and 6 (round-type protrusion) showed the relatively high velocity of 0.535 m/s and 0.558 m/s, respectively, indicating a uniform flow distribution. From the velocity and pressure at the outlet, shape 4 also displayed a relatively uniform fluid velocity and pressure, indicating that fluid from the inlet rapidly and uniformly reached the outlet, however, from detailed data of velocity, pressure and flowrate obtained from 9 sections at the outlet, shape 6 revealed the low standard deviations for each section. Therefore, shape 6 was deemed to induce the ideal flow, since it maintained a uniform pressure, velocity and flowrate distribution. [ABSTRACT FROM AUTHOR]

The identification process of different lithologies, hydrocarbons, and water-saturated zones in oil and gas industries involves petrophysical studies that are carried out by geoscientists using different software packages. This study aims to propose a method by integrating mean cluster analysis and well logs to identify dominant lithologies, pore fluids, and fluids contact. For this purpose, initially, K-mean cluster analysis is applied to density log and P-wave velocity data of three wells in order to group them into different clusters. Based on centroids of each cluster, different lithologies have been identified. The density log equation has been utilized to compute the porosity of each cluster, and the mean of each density log cluster is used as matrix density. Next, sonic log equation has been inverted to compute the fluid velocity and the mean of each P-wave velocity cluster is used as matrix velocity. For the fluid density, sonic and density log equations are jointly inverted to compute the fluid velocity of each cluster. The fluid bulk modulus and acoustic impedance are computed using fluid density and velocity. Based on the results of K-mean cluster analysis, different lithologies (shale, sandstone, and limestone) have been recognized successfully. In well-1, hydrocarbon and water-saturated zones are successfully identified and fluids contact has been established in the zone of interest. However, well-2 and well-3 did not show any indications of the presence of hydrocarbon in the respective zones. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to examine the irrigant flow generated by laser-activated irrigation (LAI), in comparison with ultrasonic-activated irrigation (UAI) and syringe irrigation (SI), in the area beyond the ledge using particle image velocimetry (PIV). Background data: There was no reported study about cleaning efficacy of LAI beyond the ledge. Materials and methods: Forty-nine J-shaped root canal models (40-curvature) were instrumented to no. 35/0.06, and a ledge, 2.5mm deep, was created with no. 60/0.08 instrument at 5mm from the apical foramen in each canal. The samples were irrigated with LAI [30 mJ/5 pulse per second (pps), 30 mJ/10 pps, 30 mJ/20 pps, 50 mJ/10 pps, 70 mJ/10 pps], UAI, and SI with a tip/needle insertion depth of 5mm from the apical foramen (n = 7). PIV was performed with glass beads and a high-speed camera. Velocities were compared in the coronal and apical areas to the ledge, respectively. Results: In the apical area, all LAI groups and UAI produced a higher velocity than that of SI, and LAI at 30 mJ/20 pps and 70 mJ/10 pps showed significantly higher velocity than that of UAI (p < 0.05). In the coronal area, LAI at 30 mJ/20 pps generated a significantly higher velocity than that of UAI and SI (p < 0.05). Velocity was significantly slower in the apical area than in the coronal area in UAI and SI (p < 0.05), but was similar between both areas in LAI except at 30 mJ/20 pps. Conclusions: Among tested laser settings, higher velocity was significantly achieved by LAI at 30 mJ/20 pps and 70 mJ/10 pps compared with UAI in the canal area beyond the ledge. SI generated lower fluid movement than LAI and UAI in both canal regions. [ABSTRACT FROM AUTHOR]

In this paper, we briefly review the application of the pulsed neutron activation method in flow measurements. We discuss the steps necessary to implement this method and the numerical techniques for data analysis and calculation of the mass flow rate. We also present the analytical solution of the transport equation in a cylindrical pipe to investigate the behavior of the mean concentration as a function of travel time of the activity in the pipe and the distance between the neutron generator and gamma detector. [ABSTRACT FROM AUTHOR]

To make a deep investigation into the lubrication characteristics of the liquid metal film (LMF), the existing 2-D hydrodynamic lubrication models cannot meet the requirement as it fails to describe the flow of the liquid film at the transverse direction. This article makes the first step toward a 3-D model of the LMF at the armature/rail (A/R) interface. A 2-D Reynolds equation is derived considering the self-acceleration of the film and the Lorentz force acting on it. By coupling the electromagnetic fields, stress, and fluid fields, a magneto-elastohydrodynamic model is established completely. Based on this, the distribution characteristics of the LMF are explored which includes the distribution of the film thickness, hydrodynamic pressure, and fluid velocity. Besides, the dynamic characteristics of the LMF in the launch process are analyzed. The results show that: 1) the LMF is trapped in an arching gap in the transverse direction. The liquid pressure is symmetrically distributed along the centerline. In addition, the positive transverse fluid velocity indicates the jetting of the molten metal which may do damage to the bore. 2) At the current down-slope, the film thickness and liquid pressure both decrease rapidly which may put the film at risk of break. This article can provide a reference to the modeling of LMF hydrodynamic lubrication and help to understand the flow behavior of the liquid film. [ABSTRACT FROM AUTHOR]

During micro-scale tracer flow in porous media, the permeability and fluid velocity significantly affect the fluid dispersion properties of the media. However, the relationships between the dispersion coefficient, permeability, and fluid velocity in core samples are still not clearly understood. Two sets of experiments were designed to study the effects of tracer fluid flow velocity and porous medium permeability on the dispersion phenomenon in a core environment, using natural and sand-filled cores, respectively. From experimental data-fitting by a mathematical model, the relationship between the dispersion coefficient, flow velocity, and permeability was identified, allowing the analysis of the underlying mechanism behind this phenomenon. The results show that a higher volumetric flow rate and lower permeability cause a delay in the tracer breakthrough time and an increase in the dispersion coefficient. The core experimental results show that the dispersion coefficient is negatively correlated with the permeability and positively correlated with the superficial velocity. The corresponding regression equations indicate linear relations between the dispersion coefficient, core permeability, and fluid velocity, resulting from the micron scale of grain diameters in cores. The combination of high velocity and low permeability yields a large dispersion coefficient. The effects of latitudinal dispersion in porous media cannot be ignored in low-permeability cores or formations. These findings can help to improve the understanding of tracer flow in porous media, the design of injection parameters, and the interpretation of tracer concentration distribution in inter-well tracer tests.

To understand the sediment-transport process in an open-channel turbulent flow, the time-averaged profiles of streamwise fluid velocity and volumetric particle concentration in suspension must be given simultaneous treatment because they are closely interrelated through particle–turbulence interaction. Presence of sediment particles increases the density of a fluid-sediment mixture, which makes the flow stratified and obstructs the settling of sediment particles. The greater the amount of sediment particles in fluid, the stronger the effects of stratification and hindered settling. Therefore, generalizing existing works, this study attempts to model the velocity and concentration simultaneously, incorporating the aforementioned effects. The coupled system of odes arising from the derivation is strongly nonlinear in nature, and the analytical solution needs a special mathematical tool. To that end, a novel analytical method called the homotopy analysis method (HAM) is employed to obtain the explicit series solution to the system. The methodology is a nonperturbation approach, and the convergence can be tackled easily through some convergence control parameters. The solutions obtained are found to be stable and are validated with numerical solution as well as with relevant experimental data available in the literature. Further, the models have been physically interpreted through the effects of the turbulent factors incorporated. [ABSTRACT FROM AUTHOR]

• Influence of different underexcited operations on thermal field was studied. • 3-D complex fluid-thermal coupling analysis was implemented and described. • The calculated and measured values were in good agreement. • Conclusions provide reference for future turbogenerator design. The losses and temperatures of end parts will increase obviously in the turbogenerator end region under underexcited operation. In order to study the influence of different underexcited operations on temperature of end parts in the turbogenerator end region with magnetic shield structure, a turbogenerator is considered as an example in this paper. Three-dimensional transient electromagnetic field of turbogenerator end region is given. The magnetic density distribution of clamping plate and magnetic shield is researched. The losses of end parts and stator end cores from three-dimensional transient electromagnetic field calculation are applied to end region as heat sources under different underexcited operations. Pressure value of fan outlet and velocity values of different inlets from flow network calculations are applied to end region as boundary conditions in the 3-D fluid and thermal coupling analysis model. Further, fluid field and thermal field are calculated under different underexcited operations. The distribution laws of fluid velocity and fluid temperature in the turbogenerator end region are determined. The temperature distribution laws of the stator-end copper windings, press finger, clamping plate, screen plate, magnetic shield, and stator end cores are studied under different underexcited operations. The accuracy of numerical calculation is validated by measured values. [ABSTRACT FROM AUTHOR]

A nonlinear viscoelastic model is developed for the dynamics of nanotubes conveying fluid. The influences of strain gradients and stress nonlocality are incorporated via a nonlocal strain gradient theory (NSGT). Since at nanoscales, the assumptions of no-slip boundary conditions are not valid, the Beskok–Karniadakis theory is used to overcome this problem. The coupled nonlinear differential equations are derived via performing an energy/work balance. The derived equations along the transverse and axial axes are simultaneously solved to obtain the nonlinear frequency response. For this purpose, Galerkin's technique together with a continuation method are utilized. The frequency response is investigated in both subcritical and supercritical flow regimes. [ABSTRACT FROM AUTHOR]

Tube hydroforming (THF) experiments were performed on TP2 copper tubes under different loading velocities and fluid velocities using a self-developed measurement system to investigate dynamic frictional characteristics in the guiding zone. The results show that the coefficient of friction (COF) dynamically changes during forming experiments and decreases with tube deformation. The average descending rate and amplitude of the COF increase with increasing loading velocity. Microscopically, the micro-protrusions on the tubular surface are flattened, and the surface scratches are finer and more uniform, as the loading velocity increases, resulting in a decrease in COF. At the same external loading velocity, the COF increases with increasing fluid velocity and is also extremely sensitive to it. Moreover, improving and predicting the formability of such tubes by accurately adjusting and controlling fluid velocity in THF is valuable and critical for the future. [ABSTRACT FROM AUTHOR]

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At present, autonomous underwater vehicles (AUVs) cannot perceive local environments in complex marine environments, where fish can obtain hydrodynamic information about the surrounding environment through a lateral line. Inspired by this biological function, an artificial lateral line system (ALLS) was built on a moving bionic carrier using the pressure sensor in this paper. When the carrier operated with different speeds in the flow field, the pressure distribution characteristics surrounding the carrier were analyzed by numerical simulation, where the effect of the flow angle between the fluid velocity direction and the carrier navigation direction was considered. The flume experiment was carried out in accordance with the simulation conditions, and the analysis results of the experiment were consistent with those in the simulation. The relationship between pressure and fluid velocity was established by a fitting method. Subsequently, the pressure difference method was investigated to establish a relationship model between the pressure difference on both sides of the carrier and the flow angle. Finally, a back propagation neural network model was used to predict the fluid velocity, flow angle, and carrier speed successfully in the unknown fluid environment. The local fluid environment perception by moving carrier carrying ALLS was studied which may promote the engineering application of the artificial lateral line in the local perception, positioning, and navigation on AUVs.

The forces acting on the blades of a radial axial turbine and the fluid are analyzed for introduction of the flow into the turbine from outside at an angle relative to a direction of the peripheral speed. The tilt angle of the blade is considered to be constant relative to the wheel radius. The influence of the centrifugal force, for which a certain amount of potential energy of the fluid is needed to be overcome, is estimated. Fluid velocity and blade velocity along with the fluid pressure on a turbine blade and the pressure exerted by the centrifugal force on the fluid are presented as functions of the initial fluid velocity and the peripheral speed of the turbine for different tilt angles of the blade and different flow directions. [ABSTRACT FROM AUTHOR]

Due to the serious overheating problem of end parts in the large turbogenerator end region, accurate calculation of end-part temperature has become a key design factor. In this paper, 3-D fluid and thermal coupling model in the end region of 1250 MW turbogenerator are given. The loss values gained from 3-D transient electromagnetic field calculation are applied to the solving end region as heat sources. Pressure value of fan outlet and fluid velocities of end region inlets from flow network calculation are applied to the solving end region as boundary conditions in the 3-D fluid and thermal coupling analysis model. The fluid flow and temperature distribution of end parts in the end region of large turbogenerator with magnetic shield structure are studied under the different operation conditions. The distribution of fluid velocity in the ventilation duct of stator end core is obtained. The temperature distribution laws of stator-end copper coils, screen plate, finger plate, press plate, and magnetic shield are researched under the different operation conditions. The location of the highest temperature point in the turbogenerator end region with magnetic shield structure is determined. The accuracy of numerical calculation is validated by experimental measured values. [ABSTRACT FROM AUTHOR]