Search Results (326)

Accurate measurement of wall shear stress (WSS) is essential for both fundamental and applied fluid dynamics, where it governs boundary-layer behavior, drag generation, and the performance of flow-control systems. Yet, existing WSS sensing methods remain limited by low spatial resolution, complex instrumentation, or the need for user-dependent calibration. This work introduces a method based on artificial intelligence (AI) and Oil-Film Interferometry, referred to as AI-OFI, that transforms a classical optical technique into an automated and sensor-like platform for local WSS detection. The method combines the non-intrusive precision of Oil-Film Interferometry with modern deep-learning tools to achieve fast and fully autonomous data interpretation. Interference patterns generated by a thinning oil film are first segmented in real time using a YOLO-based object detection network and subsequently analyzed through a modified VGG16 regression model to estimate the local film thickness and the corresponding WSS. A smart interrogation-window selection algorithm, based on 2D Fourier analysis, ensures robust fringe detection under varying illumination and oil distribution conditions. The AI-OFI system was validated in the high-Reynolds-number Long Pipe Facility at the Centre for International Cooperation in Long Pipe Experiments (CICLoPE), showing excellent agreement with reference pressure-drop measurements and conventional OFI, with an average deviation below 5%. The proposed framework enables reliable, real-time, and operator-independent wall shear stress sensing, representing a significant step toward next-generation optical sensors for aerodynamic and industrial flow applications. Full article

This study investigates the application of nanofluid (iNanoW)–polymer binary flooding system to enhance oil recovery efficiency in medium-to-high permeability reservoirs. Traditional polymer flooding technologies still have the potential for further improvement in these types of reservoirs. Therefore, this study combines iNanoW with the polymer flooding system to examine its effects on the rheological properties, injectability, interfacial performance, sweep volume, and recovery factor of the polymer solution. Experimental results show that iNanoW significantly improves the injectability of the polymer solution. The introduction of iNanoW reduces the size of polymer aggregates, as demonstrated by aggregate size and rheological performance experiments. Power-law model analysis reveals that the flow behavior of the polymer solution is further improved with the introduction of iNanoW, manifested by weakened shear-thinning behavior, reduced viscosity, and optimized flowability, which in turn helps to improve oil recovery efficiency. Moreover, iNanoW interacts with polymer molecules, lowering the surface tension and enhancing wettability, thereby improving oil–water separation efficiency. Core flooding experiments show that the introduction of iNanoW significantly increases sweep volume, particularly in medium- and small-pore spaces, where oil recovery efficiencies reached 57.97% and 61.54%, respectively. These results indicate that iNanoW not only optimizes the rheological properties of the polymer solution but also improves fluid distribution during the flooding process, significantly enhancing the overall oil recovery performance. This study provides a new approach to optimizing polymer flooding technology and highlights the potential of iNanoW in improving oil recovery efficiency. Full article

Background/Objectives: Poiseuille’s law describes the influence of radius, length, viscosity, and pressure on the flow of Newtonian fluids. Although bone cement is a non-Newtonian, shear-thinning, and polymerizing material that does not comply with this law in any predictive or quantitative sense, its qualitative principles may offer a didactic framework for understanding factors that affect injectability during cementoplasty. The objective of this Technical Note is to provide an educational and conceptual interpretation of Poiseuille’s law as it relates to trocar selection, cement behavior, and procedural planning. Methods: This work presents theoretical calculations based on the r⁴/L component of Poiseuille’s equation, using manufacturer-specified internal radii for commonly used trocars. Relative flow rates were computed as r⁴/L ratios normalized to a 13-gauge, 15 cm trocar. Conceptual viscosity profiles illustrate qualitative differences among cements over time. A representative, fully anonymized clinical example is provided to illustrate the integration of these conceptual principles into practice. No experimental measurements were performed. Results: Theoretical calculations show that trocar radius has the strongest influence on theoretical flow, with an exponential effect (r⁴), whereas increasing trocar length proportionally reduces flow. Conceptual viscosity curves demonstrate the rapid rise in viscosity during polymerization and highlight the importance of timing and cement selection. The clinical example illustrates how trocar choice, access planning, and cement viscosity are adapted to lesion morphology and cortical integrity. Conclusions: Poiseuille’s law cannot model or predict bone cement behavior and has no procedural or clinical validity in cementoplasty. Its use in this Technical Note is strictly educational, providing a qualitative framework to illustrate general relationships between equipment characteristics, viscosity evolution, and resistance during injection, without offering clinical guidance or implying any impact on procedural planning, safety, or outcomes. Full article

The primary objective of this work is to provide new solutions to increase impact protection, using a three-dimensional textile imbibed with a shear-thinning fluid. An extensive analysis showed a scarcity of research papers related to the damping capacity of deformable porous materials imbibed with non-Newtonian fluid. No studies were found for shear-thinning fluid flow inside highly compressible foams or other soft, porous materials. The damping capacity of the imbibed material was evaluated using impact with a dropping weight. Polyvinyl alcohol solution mixed with water was used for imbibition of a three-dimensional textile. Hydrophilized carbon nanofibers were also added to the solution to augment the shear-thinning behavior. The measured impact force for imbibed samples showed an important reduction compared to the impact force for the dry material. This research does not focus on flow phenomena at the microstructural level but instead aims to highlight the macroscopic attenuation effect that occurs during the compression of the imbibed material. Full article

Pain and variable uptake remain practical barriers to needle-based delivery. Device-level vibration has emerged as a simple strategy for improving tolerability and dispersion, but its fluid-mechanical basis remains incomplete. Using a lattice Boltzmann model with a porous-media skin surrogate, we applied time-periodic inlet pressures at 0%, 16.6% ($\mathsf{\Delta }{P}_1$), and 35.1% ($\mathsf{\Delta }{P}_2$) amplitudes to Newtonian, model shear-thinning, and clinically measured protein formulations. We quantified the wall shear stress, wetted area, dispersion length, and pressure cost over one cycle. Vibration increased the normalized wetted area by 10.6% for Newtonian flow and by 15.9% and 21.3% for the non-Newtonian cases at $\mathsf{\Delta }{P}_1$ and $\mathsf{\Delta }{P}_2$, respectively, while advancing the penetration front and lateral dispersion. The one-cycle pressure cost per wetted area decreased by 3.9% for Newtonian flow and by 5.96% and 7.80% for non-Newtonian flows. For shear-thinning fluids, the wall-shear history was reshaped, with a brief early amplification and late-phase mean reductions of 10.3% and 13.3% at $\mathsf{\Delta }{P}_1$ and $\mathsf{\Delta }{P}_2$. These results establish a fluid-mechanical mechanism linking clinically relevant vibration amplitudes to reduced sustained shear exposure, deeper and broader depot formation, and improved conditions for drug uptake. Full article

Particle-laden flows in non-Newtonian fluids are encountered in a variety of industrial applications, such as concrete pumping and battery electrode slurry processing, where accurate prediction of particle migration is essential for performance and product quality. This work investigates fully developed suspension flows in circular tubes, combining the shear-induced diffusion framework of Phillips et al. with the Krieger–Dougherty relative viscosity and the Carreau–Yasuda constitutive model. Unlike previous studies that generally rely on Newtonian or simple non-Newtonian rheology models, we employ the Carreau–Yasuda model, a more sophisticated constitutive relation that captures both shear-thinning behavior and Newtonian plateau regimes. By applying nondimensionalization and variable transformations, we reduce the governing coupled differential equations to a system of nonlinear algebraic equations, which allows for efficient computation of both particle concentration and velocity profiles. A systematic parametric study was conducted to evaluate the influence of several factors, including the pressure gradient, average particle concentration, and the five parameters of the Carreau–Yasuda model. Additionally, the migration parameter $\alpha =K_c/K_{\eta }$ was considered. The results reveal how the increased rheological complexity of the Carreau–Yasuda model significantly alters the migration dynamics when compared to simpler models. These novel findings have direct implications for optimizing industrial processes involving highly loaded suspensions, offering more accurate predictions of particle behavior under varying flow conditions. For the validation of our findings, experimental data in the literature was used. Full article

To achieve the upcycling of annually upsurging lignocellulosic wastes, the artificial humification of furfural residue is investigated under hydrothermal conditions with the objective of producing a high-concentration nitrogen-phosphorus-potassium (NPK) suspension fertilizer. Through orthogonal analysis, process conditions are optimized as a liquid-to-solid (aqueous KOH to furfural residue) ratio of 15, a reaction time of 5 h and a hydrothermal temperature of 160 °C. Subsequently, we screen out a formulation of suspension agents to stabilize the alkaline leachate, in which 0.50% sodium lignosulfonate, 0.20% xanthan gum and 0.05% potassium sorbate are incorporated via wet ball-milling. The Herschel–Bulkley equation well fits the rheological characteristics of the resulting suspension fertilizer with R² value exceeding 0.99. This suspension system is thus determined as one pseudoplastic non-Newtonian fluid. Due to higher static viscosity, it demonstrates superior anti-agglomeration capacity within a temperature range of 15–55 °C, while flowing smoothly through pipes during high-speed spraying onto the soil relied on its shear thinning. These findings provide novel insights for the high-value utilization of bio-waste and the development of new fertilizers with less consumption of energy and water. Full article

Gas well deliquification is a key technology for mitigating liquid loading and restoring or enhancing production capacity in ultra-deep, high-temperature, and high-pressure gas wells. The abnormal corrosion behavior observed in the gas lift tubing of the Well X-1 oilfield in western China, within the 50–70 °C interval (1000–1500 m), was investigated. By analyzing the asymmetric wall thinning and axial groove morphology on the inner surface of tubing and then establishing a two-dimensional model of the vertical wellbore, the gas–liquid flow behavior and associated corrosion mechanisms were also elucidated. Results indicate that the flow pattern evolves from slug flow at the bottomhole, through a transitional pattern below the gas lift valve, to annular-mist flow at and above the valve. The wall shear stress peaks at the gas lift valve coupled with the significantly higher fluid velocity above the valve, which markedly elevates the corrosion rate. In this regime, the resultant annular-mist flow features a high-velocity gas core carrying entrained droplets, whose impingement synergistically enhances electrochemical corrosion, forming severe groove-like morphology along the inner tubing wall. Therefore, the corrosion in this well is attributed to the synergistic effect of the mechano-electrochemical coupling between multiphase flow and electrochemical processes on the inner surface of the tubing. Full article

This study investigated the influence of coconut oil concentration (0–2%) on the nonlinear rheological and thermal behavior of soy protein concentrate (SPC) mixtures and integrated these data into computational fluid dynamics (CFD) models to predict flow behavior during high-moisture extrusion. Temperature sweep tests revealed that increasing oil content elevated the onset and peak gelation temperatures from 64.13 to 70.21 °C and 70.29 to 76.08 °C, respectively, while decreasing gelation enthalpy from 4.05 J/g to 2.81 J/g. Large-amplitude oscillatory shear (LAOS) analysis showed a shift from strain-stiffening (e₃/e₁ > 0.15) behavior to strain-thinning (e₃/e₁ < 0.05) behavior with increasing oil, accompanied by enhanced shear-thinning behavior (v₃/v₁ < 0). Integrating these nonlinear parameters into the CFD simulations enhanced model accuracy relative to the SAOS-based approach, resulting in lower RMSE values (≤4.41 kPa for pressure and ≤0.11 mm/s for velocity) and enabling more realistic prediction of deformation and flow under extrusion-relevant conditions, a capability that conventional SAOS-based models could not achieve. Predicted outlet melt temperatures averaged 70.27 ± 1.55 °C, consistent with experimental results. The findings demonstrate that oil addition modulates protein network formation and flow resistance, and that nonlinear rheology-coupled CFD models enable reliable prediction of extrusion behavior. Overall, this study provides a novel rheology-driven modeling strategy for enhancing the design and optimization of oil-enriched plant-protein extrusion processes. Full article

Microfluidics is considered a revolutionary interdisciplinary technology with substantial interest in various biomedical applications. Many non-Newtonian fluids often used in microfluidics systems are notably influenced by the external active fields, such as acoustic, electric, and magnetic fields, leading to changes in rheological behavior. In this study, a numerical investigation is carried out to explore the rheological behavior of non-Newtonian fluids in a T-shaped microfluidics channel integrated with complex micropillar structures under the influence of acoustic, electric, and magnetic fields. For this purpose, COMSOL Multiphysics with laminar flow, pressure acoustic, electric current, and magnetic field physics is used to examine rheological characteristics of non-Newtonian fluids. Three polymer solutions, such as 2000 ppm xanthan gum (XG), 1000 ppm polyethylene oxide (PEO), and 1500 ppm polyacrylamide (PAM), are used as a non-Newtonian fluids with the Carreau–Yasuda fluid model to characterize the shear-thinning behavior. Moreover, numerical simulations are carried out with different input parameters, such as Reynolds numbers (0.1, 1, 10, and 50), acoustic pressure (5 Mpa, 6.5 Mpa, and 8 Mpa), electric voltage (200 V, 250 V, and 300 V), and magnetic flux (0.5 T, 0.7 T, and 0.9 T). The findings reveal that the incorporation of active fields and micropillar structures noticeably impacts fluid rheology. The acoustic field induces higher shear-thinning behavior, decreasing dynamic viscosity from 0.51 Pa·s to 0.34 Pa·s. Similarly, the electric field induces higher shear rates, reducing dynamic viscosities from 0.63 Pa·s to 0.42 Pa·s, while the magnetic field drops the dynamic viscosity from 0.44 Pa·s to 0.29 Pa·s. Additionally, as the Reynolds number increases, the shear rate also rises in the case of electric and magnetic fields, leading to more chaotic flow, while the acoustic field advances more smooth flow patterns and uniform fluid motion within the microchannel. Moreover, a proposed experimental framework is designed to study non-Newtonian fluid mixing in a T-shaped microfluidics channel under external active fields. Initially, the microchannel was fabricated using a high-resolution SLA printer with clear photopolymer resin material. Post-processing involved analyzing particle distribution, mixing quality, fluid rheology, and particle aggregation. Overall, the findings emphasize the significance of considering the fluid rheology in designing and optimizing microfluidics systems under active fields, especially when dealing with complex fluids with non-Newtonian characteristics. Full article

The processing of bulk amorphous alloys is typically realized through superplastic deformation in the supercooled liquid region, and current research efforts predominantly focus on enhancing formability by optimizing processing parameters such as temperature and duration. However, excessive temperatures or prolonged exposure times can induce crystallization, which severely compromises the mechanical and functional properties of the alloy. This study presents the design of an ultrasonic vibration (UV)-assisted metal hot-forming apparatus that integrates an ultrasonic vibration field into the superplastic flow deformation of amorphous alloys. High-temperature compression experiments were conducted on Zr₅₅Cu₃₀Al₁₀Ni₅ amorphous alloy, and finite element simulations were performed to model the experimental process. Results show that ultrasonic vibration reduces the flow stress of the amorphous alloy, thereby enhancing its superplastic deformation capability. Simulation analysis reveals that surface effects arise from periodic interface separation between the pressure plate and the specimen caused by ultrasonic vibration, leading to a cyclic disappearance of friction forces, which manifest macroscopically as a reduction in effective friction. On the other hand, vibration introduces additional strain rates. Since the undercooled liquid of amorphous alloys exhibits non-Newtonian fluid behavior characterized by shear-thinning, ultrasonic vibration assistance can effectively reduce the apparent viscosity, thereby improving their filling capacity. Full article

Guar gum (GG) is a classic polysaccharide gel former in drilling fluids, but its native network is hindered by high water-insoluble residue, modest yield-point (YP) build-up and poor tolerance to temperature ≥ 120 °C and salinity ≥ 12 wt% NaCl. Here we transformed GG into a sulfonated guar gum (SGG) hydrogel via alkaline etherification with sodium 3-chloro-2-hydroxy-propane sulfonate. FTIR, EA and TGA corroborate the grafting of –SO₃⁻ groups (DS = 0.18), while rheometry shows that a 0.3 wt% SGG aqueous gel exhibits 34% higher YP/PV ratio and stronger shear-thinning than native GG, indicating a denser yet still reversible three-dimensional network. In 4 wt% Ca-bentonite mud the SGG gel film reduces API fluid loss by 12% and maintains YP/PV = 0.33 after hot-rolling at 120 °C, a retention 4.7-fold that of GG; likewise, in 12 wt% NaCl brine the gel still affords YP/PV = 0.44, evidencing electrostatically reinforced hydration layers that resist ionic compression. Linear-swell tests reveal shale inhibition improved by 14%. The introduced –SO₃⁻ functions strengthen inter-chain repulsion and water binding, yielding a thermally robust, salt-tolerant polysaccharide gel network. As a green, high-performance gel additive, SGG offers a promising route for next-generation water-based drilling fluids subjected to high temperature and high salinity. Full article

During the process of CO₂ displacing shear-thinning oil, the occurrence of fingering is a key factor contributing to a reduction in both displacement and sequestration efficiency. Existing studies typically use the average viscosity to calculate the viscosity ratio M for shear-thinning oil, overlooking the non-uniform viscosity distribution resulting from uneven shear stress. Consequently, a phase diagram based on M fails to accurately capture the underlying mechanism influencing fingering. We investigate the influence of shear-thinning on fingering patterns by analyzing viscosity heterogeneity during immiscible CO₂ flooding in porous media. The results showed the following: (1) An increase in zero-shear viscosity (μ₀) resulted in a greater viscosity difference between the two phases, which intensified interface instability, and the power-law index (n) diminished the shear-thinning effect, promoted fingering formation, and significantly reduced displacement efficiency, with a maximum reduction of 28.6% observed in this study. (2) Shear-thinning oil was more prone to capillary fingering compared to Newtonian oil under the same capillary number Ca and viscosity ratio M. (3) Intense pressure fluctuations at the displacement front combined with non-uniform viscosity distribution exacerbate interfacial instability and make shear-thinning oil more prone to capillary fingering. This study provides guidance for optimizing displacement strategies for shear-thinning fluids and advancing the practical implementation of CO₂ flooding technology. Full article

Background: Intracranial aneurysm (IA) rupture is a devastating event in neurosurgery and a leading cause of subarachnoid hemorrhage. Although aneurysm size has been traditionally emphasized, recent research has highlighted multifactorial mechanisms involving hemodynamic stress, wall degeneration, inflammation, and genetic predisposition. Methods: Evidence from animal models, human pathological studies, computational fluid dynamics analyses, genetic association studies, and advanced imaging research was reviewed to provide an integrated view of rupture mechanisms. Results: Morphological and hemodynamic studies have shown that high aspect and size ratios, coupled with low wall shear stress and an elevated oscillatory shear index, contribute to focal wall weakening. Histopathological analyses of ruptured aneurysms consistently reveal endothelial loss, smooth-muscle-cell depletion, extracellular matrix degradation, and intense inflammatory cell infiltration, with patterns such as extremely thin, hypocellular, thrombosis-lined walls. Experimental studies have identified active inflammatory pathways, including neutrophil-driven cascades via CXCL1 signaling and complement C5a–C5aR1 activation, as direct triggers of wall failure. High-resolution vessel-wall magnetic resonance imaging correlates contrast enhancement with histological evidence of inflammation and neovascularization, suggesting its utility as a biomarker of instability. Conclusions: IA rupture is driven by a dynamic interplay between adverse hemodynamic environments, inflammatory degeneration, genetic susceptibility, and pathological vascular remodeling. Integrating these mechanistic insights may improve risk stratification and guide the development of targeted preventive strategies. Full article

This study systematically investigates the complex nonlinear rheological behavior of magnetorheological fluids (MRFs) and greases (MRGs) through comparative experiments under two shear modes (steady-state shear and large-amplitude oscillatory shear) at room temperature. Results demonstrate that during steady-state shear tests, the apparent viscosity of both materials decreases with the increasing shear rate, exhibiting shear-thinning behavior at high shear rates that aligns with the Herschel–Bulkley constitutive model. Throughout the logarithmically increasing shear rate range, the viscosity and shear stress of MRF consistently exceed those of MRG. Under low-frequency, large-amplitude oscillatory shear (LAOS) conditions, both materials display pronounced viscoelasticity and hysteresis. At higher current levels, the maximum shear stress of MRF surpasses MRG, but its hysteresis loops exhibit reduced smoothness. The Bouc–Wen model accurately characterizes the nonlinear hysteresis of both materials, with model parameters successfully identified via a genetic algorithm. This work establishes a universal framework for the dynamic mechanical response mechanisms of magnetorheological materials, providing theoretical guidance for designing and predicting the performance of smart damping devices. Full article