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•An n-HAp additive for drilling fluid was developed and compared with some selected NPs.•Sandstone particles of 0.80–3.60 mm diameters were simulated using a customized field-oriented ...flow loop.•n-HAp outperformed CuO-NP, MgO-NP, Al2O3-NP, and SiO2-based drilling muds in cutting removal.•n-HAp increased the CTR by 28–38.6%, while the NPs caused a 2.8–23.5% increase.•Eccentric pipe at 55°-inclinations resulted in the lowest CTR compared to other hole angles.
According to oilfield drilling records, improper transport of rock cuttings caused by eccentricity has led to some serious problems, such as mechanical pipe sticking, high fluid loss, and borehole expansion, which have reduced the total economic advantages associated with the well. These problems are common in directional drilling due to the substantial reduction of annular flow velocity from the narrow annulus, necessitating the need for high-functional drilling fluid components like nanoparticles (NPs).This study evaluated the performance of hydroxyapatite nanoparticles treated with sodium dodecyl sulphate (n-HAp) on the cuttings lifting ratio (CTR) of water-based mud (WBM). The rheological and filtration properties as well as the CTR performance of the designed n-HAp were compared with those of cupric oxide (CuO), nanosilica (SiO2), alumina (Al2O3), and magnesium oxide (MgO) NPs. The fluid systems lifted 0.80–3.60 mm sandstone particles through pipe angles of 0°, 55°, and 90°. Other wellbore variables investigated include annular fluid velocities of 1.5, 2.5, and 3.5 m/s, pipe eccentricity (e = 0, 0.5, and 1.0), and 0.4, 0.8, 1.2, 1.6, and 2.0 g concentrations of n-HAp. At the same 2.0 g concentration, the findings demonstrate that n-HAp performed better in cuttings removal than each of the NPs. At a 1000 s−1 shear rate, the NPs-based fluid systems increased the viscosity of the WBM (0.166 Pa. s) by 10–87 %, while the n-HAp concentration increased it by 168 %. Also, using 2.0 g concentration, the n-HAp and the NPs decreased the fluid loss of the WBM from 9.4 mL to 5.4 mL and 8.2–4.8 mL, respectively. With n-HAp, the CTR of the WBM increased the most, by 28–38.6 %, and CuO-NP (14.6–23.5 %) came next, followed by Al2O3 (9.3–18.9 %), SiO2 (5.0–13.4 %), and MgO-NP (2.8–7.7 %). Increasing eccentricity reduced the CTR of all the mud systems at all hole angles. Drilling through a 55°-pipeangle at 3.5 m/s resulted in the lowest CTR, and the obtained CTR related to this pipe angle is 58–75 % (e = 0), 53–70 % (e = 0.5), and 52–67 % (e = 1.0). These results are important for managing the drilling muds and optimizing drilling operations because they provide insight into the effect of pipe eccentricity on CTR.
•A novel and disposable compliance pump was suggested and fabricated for supplying blood into a microfluidic channel.•Correction factor (β) was adopted for improving accuracy of fluid velocity ...obtained by micro-PIV technique.•A discrete fluidic circuit model was developed for obtaining flow rate and pressure in a microfluidic channel.•Four kinds of fluid property (i.e., fluidic resistance, viscosity, time constant, and compliance) was obtained by analyzing flow rate and pressure.•The proposed method was employed successfully to detect biophysical change in suspended blood.
Blood viscosity is considered a promising indicator of cardiovascular disease and helps predict disease risks. However, conventional methods require two highly precise pumps to maintain consistent flow rates in co-flowing streams. In this study, a low-cost and disposable compliance pump was fabricated by inserting three components (a syringe needle, a blood-loaded syringe, and an air compliance unit ACU) into a three-way valve. Since the pump induces transient blood flow, accurately obtaining the transient flow rate is necessary. A correction factor was employed to improve the blood velocity obtained by microparticle image velocimetry. Air pressure inside the ACU was estimated using the ideal gas law. A discrete fluid circuit model was constructed to estimate the flow rate and pressure in a microfluidic channel. Four types of fluid physical properties (fluid resistance, fluid viscosity, time constant, and compliance coefficient) were obtained by analysing flow rate and pressure. The proposed method was employed to detect several types of suspended blood (variations in haematocrit, thermal-shocked RBCs, and RBC aggregation-enhanced blood). From the quantitative comparison, the proposed method provides better results than the previous method. Therefore, the proposed method is a promising tool for detecting biophysical variations in suspended blood.
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•The history and relevance of redox flow batteries in energy storage are highlighted.•Electrochemical engineering principles of cell design and operation are summarised.•Performance ...can be quantified at a known state of charge and modelled by multiphysics.•Reaction environment can be described by dimensionless relationships.•The importance of operational parameters is illustrated by experimental data.
Despite many studies and several extensive reviews of redox flow batteries (RFBs) over the last three decades, information on engineering aspects is scarce, which hinders progress with scale-up and implementation of this energy storage technology. This review summarises cell design requirements then critically considers design, construction and cell features together with their benefits and problems, leading to good practice through improved cell performance, knowledge and experience. Techniques for the characterisation of the reaction environment are illustrated by measurements of mass transport to (and from) electrode surfaces as a function of flow conditions, as well as pressure drop and electrolyte flow dispersion. The influence of design features on performance is illustrated by the effect of process conditions on the components of cell potential. Adequate attention to engineering aspects is seen to be critical to the effective performance of RFBs, particularly during scale-up and long-term operation. Techniques for the characterisation of reaction environment are summarised and a list of essential design and construction factors is provided. Finally, critical areas needing research and development are highlighted.
•Vibrations and instability of a fluid-conveying piezoelectric nanotube are studied considering flexoelectricity and surface elasticity.•The nanotube is subjected to a soft tissue which is modeled ...based on Kelvin-Voigt foundation.•NSGT and Euler-Bernoulli beam theory are employed.•The effects of surface elasticity and flexoelectricity on the vibration and instability behavior of the nanotube are investigated.•Size-dependency of flexoelectric and surface effects on critical flow velocity is studied.
Fluid-conveying micro/nano tubes are key tools, which have great applications in biological devices and especially smart drug delivery in order to target the cancer cells. Furthermore, exploiting the smart materials and their combination with drug delivery systems may positively affect the instability control and improve the efficiency and adaptability of design. Recently a specific size-dependent behavior for piezoelectric materials, known as flexoelectric effect, has drawn a great deal of attention. It is proven that this effect, which is resulted by coupling between the strain field and electric polarization, is of significant importance in structures with nano dimensions. This paper is carried out to investigate the vibrations and instability analysis of fluid-conveying piezoelectric nanotubes on the basis of flexoelectricity approach. The fluid-conveying nanotubes made for drug delivery targets are commonly in contact with soft tissues, which could be modeled as a Kelvin-Voigt foundation. The nonlocal strain gradient theory (NSGT) constitutive relations are employed in order to model the problem. An appropriate electric potential distribution is determined using the Maxwell's equation and Gauss's law. The Euler-Bernoulli beam theory and slip boundary conditions are exploited to derive the governing fluid-structure interaction (FSI) equation, which contains flexoelectric and surface effect terms. Galerkin's principle is hired to discretize the equation leading to an eigenvalue problem. Afterwards, the obtained characteristic equation is solved straightforwardly to gain the eigenvalues. The instability of the nanotube is investigated throughout presenting the eigenvalue diagrams. Some illustrations are employed to analyze the effect of different involved parameters on the vibrations and instability behavior of the system. The reported results in the numerical section of the paper may be helpful to achieve an efficient and accurate design of fluid-conveying nanotubes.
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Steady laminar flow of fractal fluids Balankin, Alexander S.; Mena, Baltasar; Susarrey, Orlando ...
Physics letters. A,
02/2017, Letnik:
381, Številka:
6
Journal Article
Recenzirano
We study laminar flow of a fractal fluid in a cylindrical tube. A flow of the fractal fluid is mapped into a homogeneous flow in a fractional dimensional space with metric induced by the fractal ...topology. The equations of motion for an incompressible Stokes flow of the Newtonian fractal fluid are derived. It is found that the radial distribution for the velocity in a steady Poiseuille flow of a fractal fluid is governed by the fractal metric of the flow, whereas the pressure distribution along the flow direction depends on the fractal topology of flow, as well as on the fractal metric. The radial distribution of the fractal fluid velocity in a steady Couette flow between two concentric cylinders is also derived.
•Equations of Stokes flow of Newtonian fractal fluid are derived.•Pressure distribution in the Newtonian fractal fluid is derived.•Velocity distribution in Poiseuille flow of fractal fluid is found.•Velocity distribution in a steady Couette flow is established.
Dynamics modeling and stress response solution of the liquid-filled pipe system (LFPS) are necessary to predict the reliability of the pipe. However, the existing methods still need further research ...to solve the stress response of pipe system, and the influence of fluid velocity and pressure (FVAP) fluctuations on the vibration response is not considered. Based on this, a dynamics modeling method named FEM-TMM is proposed to solve the natural characteristics and stress response of the LFPS based on the combination of the finite element method (FEM) and transfer matrix method (TMM), which can consider the fluctuations of FVAP. The incompatible solid (Solid-NC) and virtual beam (VBeam) elements are constructed to establish the finite element models of the solid and fluid domains respectively, and the coupling elements are introduced to couple the solid and fluid domains. TMM is used to solve the FVAP fluctuations of the LFPS under external excitation, and the steady-state resonant frequency and vibration mode are obtained based on the iteration method. The virtual force iteration and stress smoothing methods are adopted to solve the stress response of the LFPS, then the dynamics modeling method FEM-TMM is obtained, and the rationality of the modeling method is verified by experiments. Finally, the analysis results show that the influence of velocity fluctuation on resonance frequency and stress response can be ignored. The critical pressures of resonant frequencies are less than or equal to those of resonant frequencies without considering pressure fluctuation. There are multiple stress barriers and valleys in the different-order stress responses of the LFPS, and the pressure fluctuation will change the distribution laws and maximum peak values of the stress barriers.
•Incompatible solid and virtual beam elements are constructed to establish the dynamics model of solid and fluid domains.•FEM-TMM are proposed to solve the stress response of the pipe system considering the fluctuations of fluid velocity and pressure.•The liquid-filled pipe system has multi-order stress barriers and valleys.•The fluctuation of pressure will change the distribution laws and maximum peak values of the stress barriers.
Thanks to their versatility and their relatively low cost, packed-bed sensible heat storage systems are promising for various applications like in concentrated solar power plants, adiabatic ...compressed energy storage and pumped thermal energy storage. A versatile one-dimensional numerical model able to describe many packed-bed configurations is developed and presented. This model is able to treat liquid and gaseous heat transfer fluids, and packed bed with a monomodal or a bimodal particle size repartion, i.e. consisting of a mixture of large and small solid particles (such as rocks and sand). This configuration is commonly encountered in the literature due to the advantages it procures. The model is compared and validated with specific experimental data and results from the literature covering wide ranges of configurations and operating conditions: several heat transfer fluids (molten salts, thermal oil, air), solid materials (rocks, sand, ceramics), fluid velocities, temperature levels and packed bed configurations are successfully tested. This shows the versatility of the developed model. The influence of the fluid velocity on heat losses, thermal diffusion and fluid/solid heat exchange are analysed. It enables to determine the optimal velocity which maximizes the performance of the storage system.
•Description of a versatile numerical model for packed-bed heat storage systems.•Relevant approaches and correlations to compute a priori heat transfer coefficients.•Validation of the model in various configurations with experimental data.•Utilization of the model to investigate the fluid velocity influence.
Thermocline storage performance is studied using a numerical model with three phases (fluid, solid, wall) and one dimension, which is then validated by comparison with experimental results. The ...impact of the interstitial fluid velocity on storage performance is presented and numerical simulations show the existence of an optimal velocity of 4⋅10−4 m s−1 that maximises the storage utilisation rate (80.6%) for ideal charges between 293 °C and 393 °C. This optimal velocity remains identical when the temperature level of the storage is shifted down and slightly increases to 4.8⋅10−4 m s−1 when the temperature difference is decreased by half (343°C–393 °C). A numerical sensitivity analysis is presented on the impact of heat losses, of thermal diffusion and of the convective heat transfer between the fluid and the solid phases, providing a physical interpretation of the location of the optimum depending on operating conditions. Experimentally, the impact of fluid velocity is too moderate to observe an optimal velocity, especially because of non-ideal inlet temperature conditions, but a deterioration of storage performance is observed at the lowest and highest velocities, with respectively −2.8% and −3.8% compared to the maximal utilisation rate. This moderate influence of both fluid velocity and temperature shows that thermocline storage presents good robustness of its performance to variations in operating conditions.
•Performances evaluation of dual-media thermocline storage for CSP.•Optimal interstitial fluid velocity that maximises the utilisation rate.•At low velocity heat losses and thermal diffusion deteriorate storage performance.•At high velocity convective heat transfer degradation between fluid and solid.
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