Journal of Non-Newtonian Fluid Mechanics最新文献

{"title":"Evaluating viscoplastic properties with rheometry and PIV measurements in pipeline flows","authors":"Gláucio Kenji Matoba ,&nbsp;Daiane Mieko Iceri ,&nbsp;Helder Lima de Moura ,&nbsp;Roney Leon Thompson ,&nbsp;Annie Fidel-Dufour ,&nbsp;Thierry Palermo ,&nbsp;Marcelo Souza de Castro","doi":"10.1016/j.jnnfm.2025.105481","DOIUrl":"10.1016/j.jnnfm.2025.105481","url":null,"abstract":"<div><div>Non-Newtonian fluids, widely utilized in industries such as cosmetics, food processing, and petroleum, exhibit shear-dependent viscosity, necessitating precise rheological characterization for effective pipeline and equipment design. In the petroleum industry, for instance, oils can transition from Newtonian to non-Newtonian behavior under specific conditions, such as long-distance horizontal flow at high pressures and low temperatures (near crystallization). In these cases, oils often behave as viscoplastic fluids, requiring a minimum shear stress, known as yield stress, to initiate flow. The Herschel–Bulkley model is a well-established equation for describing the viscous behavior of such fluids through three rheological parameters: yield stress, power-law index, and consistency coefficient. The determination of these parameters is essential for computing flow characteristics, friction factors, and pressure drops—crucial for designing efficient transport systems. This study aims to characterize a viscoplastic fluid by determining its rheological properties from rheometric and in-situ measurements. To accomplish this, an experimental setup was developed using a model fluid prepared from an aqueous Carbopol and triethanolamine (neutralizing agent) solution. In addition to traditional rheometry, an in-situ approach was evaluated, integrating Particle Image Velocimetry (PIV) with differential pressure sensor data. The velocity profiles obtained enabled the reconstruction of shear rate profiles, while pressure drop data facilitated shear stress profile determination, allowing a flow curve reconstruction. Furthermore, the modified SoFA model (Suspension of Fractal Aggregates) was applied, utilizing Carbopol and Triethanolamine concentrations to estimate the rheological parameters and obtain the corresponding flow curve. A comparative analysis was conducted between serrated parallel-plate rheometry and the PIV–pressure drop method in a commercial 2<!--> <!-->inch (0.053<!--> <!-->m) pipeline under laminar flow of the aqueous Carbopol solution. The results confirmed that the Herschel–Bulkley model effectively fit the flow curves across all methodologies, with yield stress values deviating by less than 15%. However, consistency indices (<span><math><mi>K</mi></math></span>) obtained from PIV data were overestimated, likely due to the limited shear rate range at the low mean velocities tested. This study highlights the importance of integrating traditional rheometry with in-situ techniques for a comprehensive rheological characterization.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"345 ","pages":"Article 105481"},"PeriodicalIF":2.8,"publicationDate":"2025-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144878664","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rising and migration dynamics of an air bubble close to a wall in an elastoviscoplastic fluid","authors":"G. Esposito,&nbsp;Y. Dimakopoulos,&nbsp;J. Tsamopoulos","doi":"10.1016/j.jnnfm.2025.105482","DOIUrl":"10.1016/j.jnnfm.2025.105482","url":null,"abstract":"<div><div>We investigate the buoyancy-driven motion of an air bubble rising near a vertical solid wall in an elastoviscoplastic (EVP) fluid using three-dimensional direct numerical simulations. The EVP rheology is modelled via the Saramito-Herschel-Bulkley equation, capturing viscous, elastic, and plastic behaviour. Validation against prior experimental and numerical results for unbounded domains shows excellent agreement. The nearby wall induces a lateral migration to the bubble, with the velocity depending on wall distance, bubble volume, and fluid rheology. For larger bubbles, where inertia dominates, the lateral velocity is consistently positive, indicating persistent wall repulsion, and decreases with increasing wall distance. At long times, both lateral and vertical velocities collapse onto a master curve, depending only on the instantaneous wall distance. In contrast, smaller bubbles, dominated by elastic effects, exhibit a non-monotonic lateral velocity: positive near the wall but negative at larger distances, indicating the existence of an equilibrium lateral position. A parametric study highlights the role of deformability in modulating migration dynamics. More deformable bubbles show enhanced repulsion and rising velocities that depend on terminal shape: large, oblate bubbles rise more slowly due to increased cross section in the direction of flow, while smaller teardrop-shaped bubbles rise more efficiently. Increasing the yield stress strengthens the elastic response, shifting the lateral equilibrium distance closer to the wall. Conversely, decreasing the elastic modulus (softening the medium) increases the terminal velocity and enhances wall repulsion. Finally, variations in initial bubble shape and orientation affect transient deformation but have negligible influence on long-term migration or terminal state.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"345 ","pages":"Article 105482"},"PeriodicalIF":2.8,"publicationDate":"2025-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144886963","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The role of viscoelastic stress in an abruptly converging/diverging channel under the thin film approximation","authors":"M.H. Sari ,&nbsp;H. Ahmed ,&nbsp;C. Putignano ,&nbsp;G. Carbone ,&nbsp;L. Biancofiore","doi":"10.1016/j.jnnfm.2025.105469","DOIUrl":"10.1016/j.jnnfm.2025.105469","url":null,"abstract":"<div><div>We analyze a viscoelastic fluid, modeled by the Oldroyd-B constitutive equation, flowing in a sliding abruptly converging/diverging channel. We have chosen this geometry since it has connections to the typical elastohydrodynamic lubricated (EHL), for which recently (Sarı et al., 2024) have illustrated how a viscoelastic lubricant has a positive effect on the tribological performance by raising load and decreasing friction coefficient. We assume that the channel is thin and the magnitude of the “jump” is small enough allowing to take advantage of the thin film approximation. We observe that the step location is a critical factor for generating viscoelastic pressure due to the positive and constant increase in the volumetric flow rate. Presence of viscoelasticity quantified by the ratio between fluid relaxation time and residence time, called Deborah number. A high Deborah number leads to a significant increment in pressure if the step is close to the inlet, while, if it is close to an outlet, the pressure decreases compared to Newtonian flows. While in most of the work, the pressure at the boundaries (inlet and outlet) is set to zero, we also tested more realistic boundary conditions in which the pressure is equal to the average elastic stress, showing that the two kinds of boundary conditions have a similar qualitative behavior. Lastly, a texture geometry, composed by one converging followed by one diverging steps, is inspected to mimic an EHL profile. We find what is the optimal distance between the steps to maximize the load. The role of the elastic stress in this texture profile is finally discussed.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"345 ","pages":"Article 105469"},"PeriodicalIF":2.8,"publicationDate":"2025-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144828746","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tracking polymer orientation and flow leading to unsteady cross-slot flow: High-speed imaging and modeling","authors":"Paul F. Salipante ,&nbsp;Michael Cromer ,&nbsp;Gerardo E. Pradillo ,&nbsp;Steven D. Hudson","doi":"10.1016/j.jnnfm.2025.105471","DOIUrl":"10.1016/j.jnnfm.2025.105471","url":null,"abstract":"<div><div>Viscoelastic flow instabilities limit polymer processing rates. High-speed optical measurements of stress and flow are used to provide insight into the relationships between polymer orientation and flow field that lead to viscoelastic fluctuations and instability. The flow of high-molar-mass polyethylene oxide solutions through a cross-slot geometry transitions from a symmetric flow into an asymmetric flow that continually switches its asymmetric configuration at sufficiently high flow rates. Data was acquired by synchronized particle velocimetry and polarization imaging at sub-ms resolution. Three-dimensional numerical simulations using the Giesekus constitutive model demonstrate similar flow switching behavior. Both experiments and simulations show a growth of flow–polymer misalignment near stagnation points prior to switching of the flow asymmetry direction. The role of polymer misalignment demonstrates the important role of stagnation points in flow fields, and this understanding may suggest ways to improve control of instabilities for more efficient processing.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"345 ","pages":"Article 105471"},"PeriodicalIF":2.8,"publicationDate":"2025-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144895883","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Smooth thin-layer asymptotic expansions for free-surface yield-stress flows","authors":"Danila Denisenko,&nbsp;Gaël Loïc Richard,&nbsp;Guillaume Chambon","doi":"10.1016/j.jnnfm.2025.105456","DOIUrl":"10.1016/j.jnnfm.2025.105456","url":null,"abstract":"<div><div>We derive two asymptotic expansions with a smooth velocity field for free-surface viscoplastic flows down an inclined plane in the shallow-flow approximation. The first expansion is based on the classical Herschel–Bulkley constitutive law by using asymptotic matching at the interface between the pseudo-plug and the sheared layer. In contrast to previous works, where authors considered only one term in the transition layer, we compute two extra terms to guarantee a smooth transition of the inertial contribution from the sheared layer to the pseudo-plug. However, the terms associated to the transition layer are solutions of nonintegrable equations, thus preventing the potential use of this expansion for deriving a shallow-flow model. The second asymptotic expansion is based on an alternative tensorial extension of the Herschel–Bulkley law, for which the alignment between the yield-stress tensor and the strain-rate tensor is relaxed, while the von Mises criterion is kept. In this case, smooth asymptotic expansions of the velocity field are given by fully analytical expressions. Comparison of these two expansions with experiments shows that both give essentially equivalent and relatively good agreement.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"344 ","pages":"Article 105456"},"PeriodicalIF":2.8,"publicationDate":"2025-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144724547","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Linear instability in planar viscoelastic Taylor–Couette flow with and without explicit polymer diffusion","authors":"Miguel Beneitez ,&nbsp;Soufiane Mrini ,&nbsp;Rich R. Kerswell","doi":"10.1016/j.jnnfm.2025.105459","DOIUrl":"10.1016/j.jnnfm.2025.105459","url":null,"abstract":"<div><div>Elastic turbulence has been found in computations of planar viscoelastic Taylor–Couette flow using the Oldroyd-B model, apparently generated by a linear instability van Buel et al. (2018). We demonstrate that no such linear instability exists in the governing equations used unless some diffusion is added to the polymer conformation tensor equation, as might occur through a diffusive numerical scheme. With this addition, the polymer diffusive instability (PDI) Beneitez et al. (2023) exists and leads to chaotic flows resembling those found by van Buel et al. (2018). We show how finite volume or finite-difference discretisations of the governing equations can naturally introduce diffusive errors near boundaries which are sufficient to trigger PDI. This suggests that PDI could well be important in numerical solutions of wall-bounded viscoelastic flows modelled using Oldroyd-B and FENE-P even with no polymer stress diffusion explicitly included.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"345 ","pages":"Article 105459"},"PeriodicalIF":2.8,"publicationDate":"2025-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144748967","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A generalized lumped-parameter model for analyzing external gear machines with shear-thinning operating fluids","authors":"Austin Zapata ,&nbsp;Andrea Vacca ,&nbsp;Rich Diemar ,&nbsp;Mark Hamersky ,&nbsp;David Oertel","doi":"10.1016/j.jnnfm.2025.105470","DOIUrl":"10.1016/j.jnnfm.2025.105470","url":null,"abstract":"<div><div>External gear machines are frequently used to transport non-Newtonian fluids in high pressure applications. However, a coexistence of low viscosity and significant shear thinning can present pumping challenges for off-the-shelf EGM designs. These difficulties arise in part due to the effects of viscoelasticity on the displacing action of the pump and the internal flow leakages. Previous studies have focused on three-dimensional CFD, but limited work has been done on a simulation tool for these effects which considers the radial micromotions of the gears. In this work, a fast lumped-parameter model for the simulation of external gear machines with non-Newtonian operating fluids is developed by dividing the pump into several control volumes and flow paths between them. A method of estimating flow for non-Newtonian fluid models is proposed as well as a novel Reynolds-type equation, and both are implemented within the model. The article then proceeds to compare the mean flow and pressure ripple predicted by this model with experiments to validate the methodology. The mean relative error of the model for the steady-state flowrate prediction is found to be 1.5 % and that of the amplitude prediction for the transient pressure ripple response is found to be 7.4 %. Finally, the results of the model are discussed and conclusions are drawn.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"344 ","pages":"Article 105470"},"PeriodicalIF":2.7,"publicationDate":"2025-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144686338","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dynamics of bubbles rising in viscoelastic liquids and birefringence measurement in the presence of a surfactant","authors":"Pınar Eribol ,&nbsp;Arda Inanc ,&nbsp;Ebru Sarioglu ,&nbsp;Erkan Senses ,&nbsp;A. Kerem Uguz","doi":"10.1016/j.jnnfm.2025.105458","DOIUrl":"10.1016/j.jnnfm.2025.105458","url":null,"abstract":"<div><div>A comprehensive study was conducted on the dynamics of bubbles in a 0.10–0.40 wt% polyacrylamide (PAAM) solution in the presence and absence of a surfactant, considering various shape parameters and dimensionless numbers, for a broad range of bubble volumes, from 5 to 2000 mm³. A detailed rheological analysis is performed for the chemical solutions. A safe injection period is determined such that a bubble is unaffected by another one. Unsteady results are presented. Steadiness of the bubble is checked for various shape parameters, and safe column length is determined. Uncertainty analysis is also performed. Cusp formation at the bubble tail and its correlation with the surrounding stress were assessed using flow birefringence. No discontinuity in bubble velocity is reported. As the water-soluble surfactant, sodium dodecyl sulfate (SDS), is added at 10 and 100 ppm concentration, the bubbles stretch out more in the vertical direction, and cusp formation commences at a lower volume and is more pronounced.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"344 ","pages":"Article 105458"},"PeriodicalIF":2.7,"publicationDate":"2025-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144686182","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhanced double distribution function lattice Boltzmann method for simulation of viscoelastic and shear-thinning fluids flow","authors":"Hamed Vaseghnia ,&nbsp;Espen Jettestuen ,&nbsp;Knut Erik Teigen Giljarhus ,&nbsp;Olav Aursjø ,&nbsp;Jan Ludvig Vinningland ,&nbsp;Aksel Hiorth","doi":"10.1016/j.jnnfm.2025.105467","DOIUrl":"10.1016/j.jnnfm.2025.105467","url":null,"abstract":"<div><div>In this study, we use a two-dimensional multiple relaxation time (MRT) approach for simulating polymeric fluids. A correction term is introduced into the source term to remove non-physical terms and improve numerical accuracy of the simulations. The correction term preserves the locality of the collision process and ensures numerical stability across a range of Weissenberg numbers when coupled with non-linear constitutive equations.</div><div>This approach is applied to the Phan-Thien-Tanner (PTT) model and the Oldroyd-B model, where the first exhibits viscoelastic and shear-thinning behavior while the second is purely viscoelastic. To evaluate the numerical accuracy and stability of the proposed MRT-LBM approach, we apply it to planar Poiseuille flow as well as simplified four-roll mill benchmarks. In the case of the four-roll mill, we specifically examine the effects of shear-thinning and viscoelasticity in steady elongational flows and their transitions to oscillatory and chaotic or turbulent behaviors, known as elastic instability. Our results indicate that the non-linearity in the stress-strain rate relationship and the microstructural dynamics of polymer chains, as described by non-linear constitutive models, make the standard BGK-LBM approach incapable to accurately capture the complex behavior of polymers without introducing numerical artifacts. On the other hand the MRT-LBM method maintains numerical stability and accuracy across a broad range of Weissenberg (up to <span><math><mrow><mi>W</mi><mi>i</mi><mo>=</mo><mn>20</mn></mrow></math></span>) and should therefore be the method of choice when simulating these types of flows.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"344 ","pages":"Article 105467"},"PeriodicalIF":2.7,"publicationDate":"2025-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144678802","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Saffman – Taylor instability in poorly miscible viscoelastic flows","authors":"Oleg A. Logvinov ,&nbsp;Isabel M. Irurzun","doi":"10.1016/j.jnnfm.2025.105468","DOIUrl":"10.1016/j.jnnfm.2025.105468","url":null,"abstract":"<div><div>A renowned problem of a viscous fluid displacement by a less viscous one from a Hele-Shaw cell was considered. Both fluids exhibited viscoelastic Maxwell rheology with upper convective derivative. A unified approach, which is independent of particular rheology, was applied to derive averaged two-dimensional equations of motion (so-called Hele-Shaw models). The equations were based on Reynolds class averaging procedure. Linear stability analysis was performed under these new governing equations with a special set of boundary conditions for the case of viscoelastic fluids. Dispersion curves showed that, in contrast to the purely Newtonian case, two regimes of disturbance growth were possible: viscous and elastic. We studied the influence of the main dimensionless parameters, in particular, two Deborah numbers for a displacing and a displaced fluid, and the viscosity ratio, on the growth of small disturbances on the interface. In accordance with previous theoretical studies, in the elastic regime there is a disturbance with an infinite growth rate.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"344 ","pages":"Article 105468"},"PeriodicalIF":2.7,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144653440","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}