Rheological Flow Research Articles

A numerical investigation on rheological turbulent flow through a 90° mixing elbow

Mixing elbows are widely used in various industrial processes to mix two different Newtonian or non-Newtonian fluids under turbulent flow conditions. This study numerically investigates the fluid flow and mixing characteristics in 90-degree elbows with different bend curvatures (curvature ratios of 3, 6, and 9) and Reynolds numbers ranging from 1 × 104 to 5 × 105 for both fluid types. The Reynolds-Averaged Navier–Stokes equations are solved using the turbulent k-epsilon model in ANSYS Fluent. Results show that the bend curvature creates an adverse pressure gradient that drives secondary flows, which become more pronounced with higher Reynolds numbers and lower curvature ratios. Higher Reynolds numbers improve mixing quality, as indicated by velocity and temperature variations quantified using standard deviations. For Reynolds numbers in the range of 104, velocity fluctuations initially increase, but at higher values (~ 105), they decrease, even by up to 64% as the Reynolds number rises from 1 × 105 to 5 × 105. Similarly, increasing the curvature ratio enhances mixing efficiency, with a 32% reduction in velocity fluctuations when the curvature ratio increases from 6 to 9. Furthermore, shear-thinning fluids (n=0.6\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$n = 0.6$$\\end{document}) exhibit superior mixing performance, with a standard deviation of velocity fluctuations at the outlet of 0.32, compared to 0.54 for shear-thickening fluids (n=1.4\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$n = 1.4$$\\end{document}). In terms of temperature fluctuations also, a similar trend is observed. These findings are valuable for optimizing mixing and fluid transport in industries such as chemical processing and food production, where effective mixing of complex fluids is critical. This study provides insights for improving the design of mixing systems that handle fluids with various rheological characteristics.

Experimental and numerical study of the rheological characteristics and flow law of water-based drilling fluids in high-temperature and high-pressure wellbores

Experimental and numerical study of the rheological characteristics and flow law of water-based drilling fluids in high-temperature and high-pressure wellbores

Lateral Shear Stress Calculation Model Based on Flow Velocity Field Distribution from Experimental Debris Flows

AbstractDebris flows continuously erode the channel downward and sideways during formation and development, which changes channel topography, enlarges debris flow extent, and increases the potential for downstream damage. Previous studies have focused on debris flow channel bed erosion, with relatively little research on lateral erosion, which greatly limits understanding of flow generation mechanisms and compromises calibration of engineering parameters for prevention and control. Sidewall resistance and sidewall shear stress are key to the study of lateral erosion, and the distribution of the flow field directly reflects sidewall resistance characteristics. Therefore, this study has focused on three aspects: flow field distribution, sidewall resistance, and sidewall shear stress. First, the flow velocity distribution and sidewall resistance were characterized using laboratory debris flow experiments, then a debris flow velocity distribution model was established, and a method for calculating sidewall resistance was developed based on models of flow velocity distribution and rheology. A calculation method for the sidewall shear stress of debris flow was then developed using the quantitative relationship between sidewall shear stress and sidewall resistance. Finally, the experiment was validated and supplemented through numerical simulations, enhancing the reliability and scientific validity of the research results. The study provides a theoretical basis for the calculation of the lateral erosion rate of debris flows.

Recent developments on multiscale simulations for rheology and complex flow of polymers

AbstractThis review summarized the multiscale simulation (MSS) methods for polymeric liquids. Since polymeric liquids have multiscale characteristics of monomeric, mesoscopic, and macroscopic flow scales, MSSs that relate different hierarchical levels are adequate to reproduce flow properties accurately. Our review includes pioneering studies to the most advanced MSS studies on rheology predictions and flow simulations of polymeric liquids. We discuss two major types of MSS methods: the bottom-up and model-embedded MSS methods. The former method mainly connects all-atom molecular dynamics models and mesoscopic models to predict rheological properties. In contrast, the latter method, where a microscopic or mesoscopic model is embedded in a macroscopic computational domain, is designed to predict macroscopic flow properties. Finally, we also discuss MSS methods using machine learning techniques. Graphical abstract

Numerical simulation of open channel basaltic lava flow through topographical bends

In this study, we utilised computational fluid dynamics to investigate the behaviour of open-channel basaltic lava flows navigating bends on shield volcanoes. Our focus was on understanding the relationship between flow velocity, rheology, and bend geometry. Employing a simple Force Balance Model (FBM), which considers the equilibrium between hydrostatic pressure and centrifugal force, we accurately approximated the changes in the height of the lava’s free surface through various bend geometries. Our analysis includes examining the influence of channel depth, width, and bend radius on the flow, revealing that variations in these parameters significantly affect the flow’s vertical displacement. Additionally, the bend sector angle emerged as a critical factor, indicating a minimum angle necessary for the flow to fully develop before exiting the bend.Further, we assessed the applicability of the Shallow Water Equations (SWE) for modelling the inertial displacement of the lava flow in bends, finding a good fit. The study extended to comparing the FBM’s predictions of the tilt angle of the flow’s free surface with the SWE results, showing notable agreement under specific conditions, particularly at a bend angle of 90 degrees. The impact of fluid density was also considered, revealing that density is a contributing factor to the development of the wetted line in the bend, a factor that is not captured by the simple FBM model. Finally, we explored different rheologies akin to natural lava flows, such as viscoplastic flow, and determined that factors like yield stress, consistency index, and power law index have a small impact on the flow behaviour in a steady-state condition within a bend.

Towards a framework for predicting immunotherapy outcome: a hybrid multiscale mathematical model of immune response to vascular tumor growth.

Studying tumor immune microenvironment (TIME) is pivotal to understand the mechanism and predict the outcome of cancer immunotherapy. Systems biology mathematical models can consider and control various factors of TIME and therefore explore the anti-tumor immune response meticulously. However, the role of tumor vasculature in the recruitment of T cells and the mechanism of T cell migration through TIME have not been studied comprehensively. In this work, we developed a hybrid discrete-continuum multi-scale model to study TIME. The mathematical model includes angiogenesis and T cell recruitment via tumor vasculature. Moreover, solid tumor growth, vascular growth and remodeling, interstitial fluid flow, hemodynamics, and blood rheology are all considered in the model. In addition, different aspects of T cells, including their migration, proliferation, subtype conversion, and interaction with tumor cells are thoroughly included. The model reproduces spatiotemporal distribution of tumor infiltrating T cells that mimics histopathological patterns. Furthermore, TIME model robustly recapitulates different phases of tumor immunoediting. We also examined a number of biomarkers to predict the outcome of immune checkpoint blockade (ICB) treatment. The results demonstrated that although tumor mutational burden (TMB) may predict non-responders to ICB, a combination of different biomarkers is essential to predict the majority of the responders. Based on our results, the ICB response rate varies significantly from 28 to 89% depending on the values of different parameters, even in the cases with high TMB.

Nonlinear viscoelasticity of filamentous fungal biofilms of Neurospora discreta

The picture of bacterial biofilms as a colloidal gel composed of rigid bacterial cells protected by extracellular crosslinked polymer matrix has been pivotal in understanding their ability to adapt their microstructure and viscoelasticity to environmental assaults. This work explores if an analogous perspective exists in fungal biofilms with long filamentous cells. To this end, we consider biofilms of the fungus Neurospora discreta formed on the air-liquid interface, which has shown an ability to remove excess nitrogen and phosphorous from wastewater effectively. We investigated the changes to the viscoelasticity and the microstructure of these biofilms when the biofilms uptake varying concentrations of nitrogen and phosphorous, using large amplitude oscillatory shear flow rheology (LAOS) and field-emission scanning electron microscopy (FESEM), respectively. A distinctive peak in the loss modulus (G″) at 30–50 % shear strain is observed, indicating the transition from an elastic to plastic deformation state. Though a peak in G″ has been observed in several soft materials, including bacterial biofilms, it has eluded interpretation in terms of quantifiable microstructural features. The central finding of this work is that the intensity of the G″ peak, signifying resistance to large deformations, correlates directly with the protein and polysaccharide concentrations per unit biomass in the extracellular matrix and inversely with the shear-induced changes in filament orientation in the hyphal network. These correlations have implications for the rational design of fungal biofilms with tuneable mechanical properties.

Slot coating of time-dependent structured materials: Effects of thixotropy on the flow dynamics and operating limits

Some of the most common liquid-like formulations rooted in the coating industry consist of rheologically complex structured materials such as inks, paints, and slurries. Yet, the impact of time-dependent structuring effects due to thixotropy on thin film coating applications remains elusive and still unclear. Here, we present a computational study of the effects of thixotropy on slot coating of time-dependent structured materials. By coupling a recent fluidity-based constitutive model for thixotropic materials with a well-established finite element/elliptic mesh generation method for free surface flows, we assess the role of thixotropy by comparing the predictions from the thixotropic model with those from a simple Generalized Newtonian Fluid model that uses the same flow curve for the material steady-state equilibrium viscosity. We find that thixotropy can indeed have a major impact on slot coating applications, potentially bringing strong implications not only to the flow dynamics but also to the operating limits of the process. In conclusion, the results and discussions we present in this study underscore the importance of accounting for thixotropy to genuinely model and fundamentally understand the behavior of time-dependent structured materials with complex rheology in processing flows like those ubiquitous across the broad fields of coating science and engineering.

Particle Dynamics Study on Influencing Factors of Ice Slurry Flow Characteristics in District Cooling Systems

In district cooling systems, substituting the conventional cooling medium with ice slurry represents an ideal approach to achieve economical operation. During pipeline transportation, ice slurry exhibits heterogeneous flow characteristics distinct from those of pure fluids. Consequently, investigating the flow field characteristics of non-homogeneous ice slurry, quantitatively analyzing the rheological variations and flow resistance laws due to the uneven distribution of ice particles, and standardizing the comprehension and depiction of flow patterns within ice slurry pipes hold significant theoretical importance and practical value. This study analyzes the heterogeneous isothermal flow characteristics of ice slurry in a straight pipe by employing particle dynamics and the Euler–Euler dual-fluid model. Taking into account the impact of ice particles’ non-uniform distribution on the rheological properties of ice slurry, a particle concentration diffusion equation is incorporated to develop an isothermal flow resistance model for ice slurry. The flow behavior of ice slurry with initial average ice particle fractions (IPFs) ranging from 0% to 20% in DN20 horizontal straight and elbow pipes is examined. The findings reveal that the degree of heterogeneous flow in ice slurry is inversely proportional to the initial velocity and directly proportional to the initial concentration of ice particles. When the flow velocity is close to 0.5 m/s, the flow resistance of ice particles exhibits a linear positive correlation with changes in flow velocity, whereas the flow resistance of the fluid-carrying phase displays a linear negative correlation. As the flow rate increases to 1 m/s, the contribution of each phase to the total flow resistance becomes independent of the initial velocity parameter. Additionally, the drag fraction of the ice particle phase is positively associated with the initial concentration of ice particles. Furthermore, the phenomenon of “secondary flow” arises when ice slurry flows through an elbow, enhancing the mixing of ice particles with the carrier fluid. The extent of this mixing intensifies with a decrease in the turning radius and an increase in the initial velocity.

Melting rheology of Prandtl Eyring hybrid nanofluid flow with slip condition past a Riga Wedge through Darcy-Forchheimer medium

The current matter examines the 2D flow of Prandtl Eyring hybrid (Al2O3+Cu/SA) nanoliquid through a porous media with a velocity slip mechanism along the melted Riga wedge. A combination of Alumina (Al2O3) and Copper (Cu) nanoparticles in a sodium alginate (SA) base liquid is called a hybrid nanofluid. Furthermore, the physical meaning of the flow behavior is explored with Darcy-Forchheimer. Heat sink/source, nonlinear thermal energy, and viscous dissipation, applications all need the computation of heat transference. The current flow problem is modelled in the system of highly nonlinear PDEs based on flow assumptions. We use an appropriate similarity transformation to turn these PDEs into ODEs. We simulate the obtained paired nonlinear higher-order ODEs employing the ideas from the bvp4c Matlab scheme. With the help of the graphics, several physical dimensionless factors are discussed and their unique effects on the flow profile are shown. One of the study's most notable findings is that applying boundary slip and Riga impact can increase velocity because of weak electromagnetic forces. At lower velocities, wedge flow through a Darcy-Forchheimer medium is primarily driven by viscous resistance under Darcy's law, with little in the way of inertial forces. It is also noteworthy that the temperature differential, thermal radiation, nanoparticle volume percentage, and Eckert number all enhance the nanoliquid thermal profile in both Prandtl Eyring fluid and hybrid nanofluid. The Nusselt number is increased for both the melting and fluid parameters.

Quantitative evaluation of mantle flow traction on overlying tectonic plate: linear versus power-law mantle rheology

SUMMARY Sub-plate mantle flow traction (MFT) has been considered as a major driving force for plate motion; however, the force acting on the overlying plate is difficult to constrain. One of the reasons lies in the variable rheological flow laws of mantle rocks, for example, linear versus power-law rheology, applied in previous studies. Here, systematic numerical models are conducted to evaluate MFT under variable rheological, geometrical and kinematic conditions. The results indicate that MFT with power-law rheology is much lower than that with linear rheology under the same mantle/plate velocity contrast. In addition, existence of a lithospheric root in the overlying plate could enhance MFT, where integrated normal force acting on the walls of lithospheric root is much lower than the shear force in a large-scale domain. In the acting domain of several thousand kilometres, MFT with power-law rheology is comparable to the ridge push of about 3×1012 N m−1, whereas that with linear rheology is comparable to the slab pull of about 3×1013 N m−1. The roles of MFT in driving plate motion are further analysed for the Tethyan evolution. It indicates that MFT with power-law rheology could partially support the Wilson cycles experienced in the Tethyan system, whereas that with linear rheology could easily dominate any kinds of plate tectonic evolutions. The quantitative evaluation of MFT in this study clarifies the roles of rheological flow laws on MFT and could help us to better understand the contrasting results in previous numerical studies.

The viscous-brittle transition in flowing crystal-bearing volcanic dome lavas

The ascent and advance of volcanic dome lava is non-linear and viscoelastic. There exists a mismatch between current theoretical approaches to dome lava rheology, which are based on rheological laws for viscous suspensions, and empirical experimental approaches to convolved viscous-brittle deformation, which show mixed evidence for simultaneous lava flow and fracturing. The missing requirement is a unified framework for understanding the transition between micro-mechanical flow mechanisms that are dominantly viscous, and those that include micro-cracking in multiphase suspensions such as magmas. Here, we use high-temperature compression rheology with sample-scale acoustic emission analysis to constrain the conditions under which crystal-rich volcanic dome lava can flow by mixed viscous and brittle fracturing processes at small scales, leading to ‘crackling’ acoustic signals, even at moderate shear stresses extant in nature. Using multi-directional permeability measurements on large 60 mm diameter quenched samples of natural magmas, we show that this micro-cracking flow mechanism leads to permeability anisotropy, localizing outgassing into pathways that are off-axis relative to the direction of flow. Finally, we use a scaling approach and a database of published observations from real eruptions to upscale our findings, and show that bulk, apparently ductile flow of low-porosity dome magma is likely to involve a local mixed-mode of micro-cracking and viscous flow during the shallowest portions of ascent and during emplacement on the Earth's surface. The micro-cracking involved in lava advance divorces real crystal-bearing lava emplacement from most current rheology models based on a purely viscous micro-mechanism and shows that a revised solution for the rheology of mixed brittle-viscous flow is required. By re-examining published numerical models for dome emplacement, we demonstrate that the viscous-brittle transition can be intercepted in spatially heterogeneous zones within the dome core.

Unconfined gravity current interactions with orthogonal topography: Implications for combined‐flow processes and the depositional record

ABSTRACTTurbidity current behaviour is affected by interactions with seafloor topography. Changes in flow dynamics will depend on the orientation and gradient of the topography, and the magnitude and rheology of the incoming flow. A better understanding of how unconfined turbidity currents interact with topography will improve interpretations of the stratigraphic record, and is addressed herein using three‐dimensional flume tank experiments with unconfined saline density currents that enter a horizontal basin before interacting with a ramp orientated perpendicular to flow direction. The incoming flow parameters remained constant, whilst the slope angle was independently varied. On a 20° slope, superelevation of the flow and flow stripping of the upper, dilute region of the flow occurred high on the slope surface. This resulted in a strongly divergent flow and the generation of complex multidirectional flows (i.e. combined flows). The superelevation and extent of flow stripping decreased as the slope angle increased. At 30° and 40°, flow reflection and deflection, respectively, are the dominant flow process at the base of slope, with the reflected or deflected flow interacting with the parental flow, and generating combined flows. Thus, complicated patterns of flow direction and behaviour are documented even on encountering simple, planar topographies orientated perpendicular to flow direction. Combined flows in deep‐water settings have been linked to the interaction of turbidity currents with topography and the formation of internal waves with a dominant oscillatory flow component. Here, combined flow occurs in the absence of an oscillatory component. A new process model for the formation and distribution of hummock‐like bedforms in deep‐marine systems is introduced. This bedform model is coupled to a new understanding of the mechanics of onlap styles (draping versus abrupt pinchout) to produce a spatial model of gravity‐current interaction, and deposition, on slopes to support palaeogeographical reconstructions.

The Impact of Gel Parameters on the Dispersal and Fragmentation of Hyaluronic Acid Gel Fillers within an Artificial Model of Arterial Embolism.

Accidental arterial embolization of hyaluronic acid (HA) fillers can lead to severe complications, including skin ischemia, blindness, and stroke. Currently, the intra-arterial dispersal and fragmentation behavior of HA gels is unknown but critical to our understanding of the pathomechanism of these injuries. This work introduces the Pulsatile Unit for the Laboratory Simulation of Arterio-embolic Restrictions (PULSAR) and evaluates the intravascular behavior of different HA gels. The fragmentation and dispersal behaviors of four HA gels with distinct rheological properties were evaluated via high-resolution videography and ImageJ particle size and morphology analysis. The gels' elastic modulus (G'), loss modulus (G″), tan(δ), and HA concentration were subsequently correlated with their intra-arterial behaviors. This study effectively confirms the extensive fragmentation of HA gels upon arterial inoculation, with particle sizes ranging from <50 µm to >1 mm. Gel particle size and morphology correlated most significantly with tan(δ). Conversely, arterial flow rates did not significantly influence gel fragmentation behavior, though the probability of proximal, macrovascular obstruction was affected. Overall, this study validates the PULSAR model for simulation of arterial dynamics and the testing of intravascular filler kinematics. The findings demonstrate the ability of gels to microfragment and disseminate distally, as well as induce partial proximal occlusion depending on gel rheology and arterial flow parameters.

Morphology of laminar rheological flow in polygonal ducts

Morphology of laminar rheological flow in polygonal ducts

Coupling a torque rheometer with an ultrasonic velocity profiler for evaluating multiphase fluids in oscillatory shear flows

We propose a torque rheometer coupled with an ultrasonic velocity profiler (UVP) for evaluating multiphase fluids as bulk rheology in oscillatory shear flows. The rheometer mainly consists of wide-gap coaxial cylinders, where the outer cylinder is sinusoidally oscillated and the inner cylinder is fixed to a torque sensor for measuring the wall shear stress. Based on Cauchy’s equation of motion, the spatiotemporal distribution of the shear stress is obtained from the velocity information and the wall shear stress as a boundary condition. This rheometer was applied to a carboxymethyl cellulose aqueous solution and compared with a standard torque-type rheometer. The results of the evaluated viscoelastic properties agreed well with each other, indicating the validity of the proposed rheometry. To further investigate the applicability of the rheometer to multiphase fluids, suspensions of solid spherical particles with a diameter of 220μm with volume fraction of 0.8–3.4% were measured, which are out of the applicable ranges of the standard rheometer. For volume fractions up to 3% where the UVP measurement is available, the relative viscosity agrees well with a theoretical formula. This indicates the applicability of the method to examine multiphase fluids.

Optimization of thermal performance in ternary nanofluids dynamics on curved surface through employment of active and passive strategies

Improving thermal conductivity of heat transporting fluids is one of the most effective strategies to address practical challenges relating to optimization of heat energy. This novel study aims at employment of some active as well as passive strategies to investigate their engagement in maximizing energy transportation. The active strategies include addition of nanoparticles of three different metal oxides in the water to enhance its heat conductivity. The presence of gyrotactic microorganisms in ternary nanofluid is assumed to improve solubility. We have also considered nanometric phenomenon of Brownian motion and thermophoresis which were declared most effective in heat and mass transport by Buongiorno. Moreover, effects of magnetic force, thermal radiations, nonlinear heat source, activation energy, and chemical reaction are deliberated to estimate effects of their presence on temperature and rheology of ternary nanofluid flow. Apart from said active strategies to control heat and mass flow rate, curvature of curved surface and porous media has been employed to determine their efficacy as passive controls, particularly on ternary nanofluid flow on curved surface. The modeled equations are solved numerically by MATLAB bvp4c package and solution is validated by comparison of acquired results with those already published in literature. The obtained results are discussed in details by providing physical explanations of rheological and thermal behavior of flow. The study concludes that combination of active and passive control strategies can be effectively utilized to improve overall rheological behavior and thermal performance of ternary nanofluid. This study contributes in better understanding of heat and mass transport in ternary nanofluid dynamics with active and passive control strategies promoting advances in research at intersection of these fields having wide range real-life applications and implications.

Resting time effects on flow properties of cementitious materials: a study on self-compacting concrete equivalent mortar made with recycled aggregates

The concrete equivalent mortar (CEM) method, mainly used in the laboratory, offers a course that facilitates and accelerates experimental test programs with relatively small amounts of materials. To this end, two CEM mixes, with natural and recycled aggregates, at different superplasticizer (SP) concentrations, were tested. The key objective was to investigate how CEM flow property changed at 0, 30, and 60 min of resting time, emphasizing the material’s structuring and destructuring effects. This study describes the flow behaviour of CEMs applying specific tools. Also, a vane-geometry rheometer was used to obtain rheological flow curves. Whatever the SP content in the structuring state, the results indicated reduced flow properties over time. However, an SP content of 1.3% retard the structural build-up property that was not evident at 60 min-rest time. Spread diameters ranging between 300 and 400 mm are measured with the mini cone immediately after mixing. After 60 min of resting time, these diameters were reduced between 260 and 300 mm. Remixing after prolonged rest periods reduces the flow stress values, which decrease from 10 to 18 Pa to 6 to 14 Pa. After a structural build-up at a rest time, the structural break-down effect by remixing re-fluidifies the mixtures. The fluidity has recovered its initial state, reflecting a thixotropic property.

Municipal sewage sludge dewatering performance enhancement by ultrasonic cavitation and advanced oxidation: A case study.

The number of published literature on the effect of ultrasonic cavitation and advanced oxidation pretreatment on the dewatering performance of anaerobically digested sludge is very limited. This study aims at determining the optimum operating conditions of large-scale filtering centrifuges in wastewater treatment plants. The optimum dose of hydrogen peroxide, ultrasonic power, ultrasonic duration, ultrasonic pulse and particle size distribution for improved dewatering performance were determined in this study. In addition, shear stress-shear rate and viscosity-shear rate rheograms were developed to show the rheological flow properties for varying ultrasonic power and treatment duration. Optimum sonication power, time, pulse and amplitude were determined to be 14 W, 1 min, 55/5 and 20%, respectively. At a pH of 6.8, the optimum concentration of hydrogen peroxide was found to be 43.5 g/L. The optimum hydrogen peroxide dose in the combined conditioning experiments was determined to be 500 mg/L at a pH of 3. Under these optimum conditions, capillary suction time was reduced significantly by 71.1%. This study helps to reduce polymer consumption and provides the optimum pretreatment and dewatering operating conditions, and better monitoring and control in the dewatering unit has significant impact in the overall economy of wastewater treatment plants.

Structural evolution and rheology of continuous shear-induced dense granular flow in unsteady state

The structural properties of particulate matter can significantly affect the rheology of the system. We report the structural evolution and flow properties of dense granular flows induced by Couette shear and try to reveal the relationship between them. In unidirectional shear, monodisperse particles undergo a transformation from disorder to order. Throughout this continuous process, both the velocity and shear strain rate of the particles experience alterations. By filling with particles of varying polydispersity, the structural potential of the system can be controlled, thereby influencing the extent of structural transformations. The results indicate that the transition in flow characteristics is suppressed as the initial filling in the system approaches from high to low structural potential. The results based on the local volume fraction and relative positions of particles suggest that it is due to the weakening of the structural thinning effect caused by order. We found that both fixed shear paths and more rotatable local structures caused a significant reduction in the contact force to transfer energy. Inertia number and apparent viscosity vary with volume fraction, indicating a transition in dense granular flow after volume fraction φ≳ 0.62, with the onset of significant structural thinning effects. We have revealed the physical mechanisms influencing fluidity from a local structural perspective and established the relationship between fluidity g and φ in the continuous process of unsteady flow.