Journal of Non-Newtonian Fluid Mechanics最新文献

{"title":"Magnus force reduction in a shear-thinning fluid","authors":"Sai Peng ,&nbsp;Xiang Li ,&nbsp;Li Yu ,&nbsp;Xiaoyang Xu ,&nbsp;Peng Yu","doi":"10.1016/j.jnnfm.2024.105309","DOIUrl":"10.1016/j.jnnfm.2024.105309","url":null,"abstract":"<div><p>This study aims to investigate the impact of fluid shear-thinning on the Magnus forces acting on a rotating cylinder or a sphere immersed in an unbounded flow using direct numerical simulation. The Carreau model is employed to represent the shear-thinning fluid, with the considered Reynolds number (<em>Re</em>) ranging from 0.01 to 100, Carreau number (<em>Cu</em>) from 0 to 100, power-law index (<em>n</em>) from 0.1 to 1, and viscosity ratio (<em>β</em>) from 0.001 to 0.5. The rotation rate (<em>α</em>) is fixed at 6. A characteristic Reynolds number, <em>Re</em>_c, based on a viscosity evaluated at the characteristic shear rate, <span><math><mrow><msub><mover><mi>γ</mi><mo>˙</mo></mover><mi>α</mi></msub><mspace></mspace><mo>=</mo><mspace></mspace><mi>α</mi><msub><mi>U</mi><mi>∞</mi></msub><mo>/</mo><mn>2</mn><mi>a</mi></mrow></math></span>, is introduced. It is found that, at a constant <em>Re</em>_c, compared to that in a Newtonian fluid, the Magnus force exerted on the rotating cylinder or sphere in the shear-thinning fluid is reduced. This reduction results from the difference in viscosity distribution between the upper and lower sides of the cylinder or sphere. Furthermore, our analysis demonstrates that the logarithmic reduction in the Magnus force coefficient can be expressed as a linear combination of the logarithm of the strain rate difference and the logarithm of the shear strain rate sensitive function at two limit states, <em>Cu</em>→0 or <em>Cu</em>→∞. This work may be helpful to deepen the understanding of complex rheological behavior encountered in swirling flow hydrodynamics.</p></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"333 ","pages":"Article 105309"},"PeriodicalIF":2.7,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142149200","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":"Migration of particles suspended in yield stress fluids: Insights from numerical simulation of pipe flow of 3D printable concrete","authors":"Vishwanath Ravindran ,&nbsp;Thiyagarajan Ranganathan ,&nbsp;A.V. Rahul","doi":"10.1016/j.jnnfm.2024.105305","DOIUrl":"10.1016/j.jnnfm.2024.105305","url":null,"abstract":"<div><p>In this work, we present a numerical model to analyse particle migration and its impact on local rheological properties when a high-yield stress suspension like 3D printable concrete is transported through a narrow circular pipe. The particle migration is studied through the lens of suspension rheology, where the effect of local particle concentration on rheological properties is accounted for using Krieger–Dougherty-type models. 3D printable mixtures with different aggregate-to-binder (a/b) ratios and flows at various discharge rates are evaluated. It is observed that, depending on the discharge rate and a/b ratio, the flow behaviour could deviate from that expected in a Poiseuille flow of Bingham fluid owing to shear-induced particle migration. Interestingly, as a consequence of particle migration, the formation of a local unsheared region close to the pipe wall is observed, apart from the plug zone at the pipe centre in the partially unsheared pipe flow of Bingham fluids. Often, for concrete pipe flow simulation, the particle size is not small enough to warrant local treatment since the finite size of the particle is not fully reflected in the flow domain. In this work, the developed numerical model is also extended to account for the finite particle size to study the transition between the sheared and unsheared regions and assess the effect of considering finite size in our simulation. Finally, the model’s capability to predict global pressure loss in pipe flow is assessed through comparisons with experimental results.</p></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"332 ","pages":"Article 105305"},"PeriodicalIF":2.7,"publicationDate":"2024-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142095342","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":"σOWCh: Optimally Windowed Chirp rheometry using combined motor transducer/single head rheometers","authors":"Rebecca E. Hudson-Kershaw ,&nbsp;Mohua Das ,&nbsp;Gareth H. McKinley ,&nbsp;Daniel J. Curtis","doi":"10.1016/j.jnnfm.2024.105307","DOIUrl":"10.1016/j.jnnfm.2024.105307","url":null,"abstract":"<div><p>Recent advances in rheometry exploiting frequency-modulated (chirp) waveforms have dramatically reduced the time required to perform linear viscoelastic characterisation of complex materials. However, the technique was optimised for ‘separate motor transducer’ instruments, in which the drive motor imposing the strain deformation is decoupled from the torque transducer. Whilst the use of optimised windowed chirps (OWCh) using other rheometers has been recently reported in the literature, no systematic study concerning the use of ‘combined motor transducer’ instruments (in which the motor and transducer subsystems are integrated into a single ‘head’) has been undertaken. In the present study, we demonstrate the use of OWCh rheometry using combined motor transducer/single-head rheometers using a stress-controlled operating principle, thus avoiding the reliance on complicated and instrument-specific feedback control systems that would be required to perform strain-controlled experiments. The use of stress-controlled chirps requires a modification to the established OWCh analysis protocol such that the complex viscosity <span><math><mrow><msup><mrow><mi>η</mi></mrow><mrow><mo>∗</mo></mrow></msup><mrow><mo>(</mo><mi>ω</mi><mo>)</mo></mrow></mrow></math></span> is used as an intermediate proxy function for ultimately computing the complex modulus <span><math><mrow><msup><mrow><mi>G</mi></mrow><mrow><mo>∗</mo></mrow></msup><mrow><mo>(</mo><mi>ω</mi><mo>)</mo></mrow></mrow></math></span>. This approach negates the effect of the strain offset that is inherent to stress-controlled oscillatory rheometry. Secondly, a correction algorithm and operational criteria for identifying inertial artefacts is established before we consider the impact of chirp digitisation on data acquisition. The use of stress-controlled OWCh rheometry (which we term Stress-OWCh, i.e. <span><math><mi>σ</mi></math></span>OWCh) is demonstrated for a diverse range of material classes including, Newtonian calibration fluids (silicone oil), polymer solutions (polyethylene oxide in water), an entangled polymer melt (polydimethylsiloxane), worm-like micellar systems (cetylpyridinium chloride/sodium salicylate), time-evolving critical gels (gelatin) and aging elastoviscoplastic materials (Laponite®). This novel implementation of chirp waveforms using a single-head rheometer will facilitate the wider adoption of OWCh rheometry and allow the benefits of frequency-modulation techniques to be exploited where separate motor transducer instruments are unavailable/unsuitable.</p></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"333 ","pages":"Article 105307"},"PeriodicalIF":2.7,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S037702572400123X/pdfft?md5=8699673a8af80917a3a3c894395db0a9&pid=1-s2.0-S037702572400123X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142274444","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Oscillatory one-roll and two-roll solutions in laminar viscoelastic Rayleigh-Bénard convection in a square cavity","authors":"Govind Maurya,&nbsp;Suneet Singh,&nbsp;Lalit Kumar","doi":"10.1016/j.jnnfm.2024.105308","DOIUrl":"10.1016/j.jnnfm.2024.105308","url":null,"abstract":"<div><p>Rayleigh-Bénard convection in square closed cavities filled with Oldroyd-B fluid was studied using OpenFOAM-based RheoTool. For the RBC in Newtonian fluids, the transition always occurs from conduction to steady state convection with increasing Rayleigh number (<em>Ra</em>). On the other hand, the viscoelastic fluids may also show the transition from conduction to oscillatory convection. Further increase in <em>Ra</em> may result in a steady state convective solutions. It is further noted that the behavior is similar to Newtonian fluids for larger values of viscosity ratio (<em>B</em>). Considering the abovementioned different flow behavior at different values of the parameters, it is noted that there are five different types of solutions possible for the viscoelastic fluids viz. pure conduction (PC), one roll periodic oscillations (ORPO), one roll steady state (ORSS) convection, two roll periodic oscillations (TRPO), simultaneous one and two roll steady state convection. Therefore, a bifurcation diagram in the parametric space of <em>Ra</em> and <em>B</em> is presented, depicting these five regions corresponding to each type of solution. The boundaries of these regions have been identified by numerical simulation. Note that all these regions exist in the laminar flow regime, and the transition to turbulence is not considered here. Interestingly, at low values of <em>B</em>, as one increases <em>Ra</em>, it is seen that the ORSS region is sandwiched between ORPO and TRPO. The likely reason for this interesting behavior is explained. Moreover, representative solutions in each region in terms of isotherms, streamlines, and vector plots have been included to demonstrate the dynamics of each delineated region.</p></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"332 ","pages":"Article 105308"},"PeriodicalIF":2.7,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142136315","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":"Non-Newtonian behaviors of ferrofluid Couette–Poiseuille flows in time-varying magnetic fields","authors":"Wenming Yang ,&nbsp;Yifan Li ,&nbsp;Jiantuo Ren ,&nbsp;Xiaolong Yang","doi":"10.1016/j.jnnfm.2024.105306","DOIUrl":"10.1016/j.jnnfm.2024.105306","url":null,"abstract":"<div><p>We analyze the fully developed Couette–Poiseuille flows of ferrofluids between two parallel flat walls subject to three types of time-varying magnetic fields. In these scenarios, ferrofluids exhibit diverse non-Newtonian characteristics such as distinct flow velocity distribution, apparent viscosity and shear stress compared to ordinary Couette–Poiseuille flows. The influence of spin viscosity is explored first through the solution of the governing equations with zero and non-zero spin viscosities. It shows that although the value of the spin viscosity is very small, its inviscid limit would have great influence over the velocity and spin velocity distributions. The assumption of zero spin viscosity leads to an exaggerated non-Newtonian behavior induced by time-varying magnetic fields in the ferrofluid Couette–Poiseuille flows. Then the solutions of equations with non-zero spin viscosity are utilized to delve into non-Newtonian behaviors of ferrofluid Couette–Poiseuille flow under the application of the three time-varying magnetic fields. The results indicate that negative rotational viscosity will occur if the dimensionless frequency lies in the range 1–10, which is a distinguishing feature compared with Newtonian flows. At this point, non-Newtonian flow induced by magnetic field arises, although this effect is very tiny. Within the same frequency range, reversed tangential stress appears in strong uniform alternating magnetic fields. The minimum negative rotational viscosity may arrive at up to 20 % of the intrinsic viscosity in the rotating magnetic field when the magnetization relaxation time is 4 ms.</p></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"332 ","pages":"Article 105306"},"PeriodicalIF":2.7,"publicationDate":"2024-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142095341","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":"Preface to Special Visual Issue: E Mitsoulis","authors":"Yannis E. Dimakopoulos ,&nbsp;Georgios C. Georgiou","doi":"10.1016/j.jnnfm.2024.105297","DOIUrl":"10.1016/j.jnnfm.2024.105297","url":null,"abstract":"","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"331 ","pages":"Article 105297"},"PeriodicalIF":2.7,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141993115","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":"Micro-PIV of viscoelastic fluid flow in microporous media","authors":"Victor C. Ibezim ,&nbsp;David J.C. Dennis ,&nbsp;Robert J. Poole","doi":"10.1016/j.jnnfm.2024.105295","DOIUrl":"10.1016/j.jnnfm.2024.105295","url":null,"abstract":"<div><p>The present experimental investigation combines the bulk flow properties of polymer solutions and measurable rheological parameters as they flow through a distinctive micro-porous structure, with micro-PIV (micro-particle image velocimetry) to measure the velocity distribution and velocity fluctuations within individual pores of a novel porous glass structure. To investigate the effects of fluid elasticity at pore scale, aqueous solutions of a polyacrylamide (PAA) &amp; polyethylene oxide (PEO) in the concentration range of 50–200 ppm, which were characterized in both shear and extensional flows using shear and capillary break-up extensional rheometers (CaBER) respectively, were used as working fluids. The velocity field measurement includes the velocity magnitude and fluctuation intensity in several different pores within the porous material across a Weissenberg number <span><math><mrow><mi>W</mi><mi>i</mi></mrow></math></span> range of approximately 0.01 to 1 for each of the test fluids. The global averaged fluctuation intensity increases with <span><math><mrow><mi>W</mi><mi>i</mi></mrow></math></span> but the critical value, which indicates the onset of significant unsteadiness (i.e. well above noise floor/Newtonian baseline) within the flow at pore scale gives an approximately constant value of <span><math><mrow><mi>W</mi><mi>i</mi><mo>≈</mo></mrow></math></span>0.4, which is almost 40 times higher than the value that is observed in the pressure-drop measurements for the data to rise above the Newtonian base line. We therefore postulate that the enhanced pressure-drop behaviour of the bulk flow may not be due to local velocity fluctuations within the pores but due to mean flow effects, at least over a significant portion of the data (up to <span><math><mrow><mi>W</mi><mi>i</mi><mo>≈</mo></mrow></math></span>0.4).</p></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"332 ","pages":"Article 105295"},"PeriodicalIF":2.7,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0377025724001113/pdfft?md5=a43a620daf8334c96025b7999426f7b0&pid=1-s2.0-S0377025724001113-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141990463","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Editorial for XXI International Workshop on Numerical Methods for non-Newtonian Flows 2023","authors":"Mónica S.N. Oliveira ,&nbsp;Konstantinos Zografos ,&nbsp;Marco Ellero ,&nbsp;Patrick D. Anderson ,&nbsp;Robert J. Poole","doi":"10.1016/j.jnnfm.2024.105296","DOIUrl":"10.1016/j.jnnfm.2024.105296","url":null,"abstract":"","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"332 ","pages":"Article 105296"},"PeriodicalIF":2.7,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142171858","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 life and work of Ken Walters FRS (1934-2022)","authors":"","doi":"10.1016/j.jnnfm.2024.105258","DOIUrl":"10.1016/j.jnnfm.2024.105258","url":null,"abstract":"<div><p>Ken Walters was one of the most prominent rheologists of recent times. He brought his mathematical training to rheology and pioneered analysis of many common test procedures. In order to do this he contributed to the formation of nonlinear constitutive equations for viscoelastic fluids and he was an early exponent of computational studies in rheology. He also applied his skills in fruitful collaborations with industry - notably the oil and china clay industries. He was born in Swansea, South Wales, in 1934 and he remained a devoted Welshman despite travelling widely. His academic studies in Swansea with James Oldroyd led to the PhD degree in 1959. In 1960, after a stint in the U.S.A., he was appointed as a Lecturer at Aberystwyth, and he remained there until his death in 2022. He built a very strong research team at Aberystwyth which became a dominant factor in the rheological scene in the United Kingdom.</p><p>He was a keen promoter of rheology and he assisted in the organisation of many conferences and meetings. He was the founding Editor of the Journal of Non-Newtonian Fluid Mechanics (JNNFM). He authored or co-authored four well-known books on rheology plus several tracts of a religious nature - Ken was always a devoted Christian. He was also a very able sportsman especially at cricket and golf. He is survived by his wife Mary, three children and seven grandchildren.</p></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"330 ","pages":"Article 105258"},"PeriodicalIF":2.7,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141024695","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":"Capillarity-driven thinning and breakup of weakly rate-thickening fluids","authors":"Jianyi Du ,&nbsp;Hiroko Ohtani ,&nbsp;Kevin Ellwood ,&nbsp;Gareth H. McKinley","doi":"10.1016/j.jnnfm.2024.105294","DOIUrl":"10.1016/j.jnnfm.2024.105294","url":null,"abstract":"<div><p>A number of commercial fluids, including synthetic automotive oils, food and consumer products containing polymer additives exhibit weakly rate-thickening responses in the final stages of capillarity-driven thinning, where a large accumulated strain and high extensional strain rate alter the thinning dynamics of the slender liquid filament. Consequently, measurements of capillarity-driven thinning dynamics typically feature two distinct regions at the early and late stages of the filament breakup process, each dominated by distinct mechanisms. These features have been incorporated in a simple Inelastic Rate-Thickening (IRT) model with linear and quadratic contributions to the constitutive stress–strain rate relationship, in which the apparent extensional viscosity slowly thickens at high strain rates. We numerically compute the thinning dynamics of the IRT model assuming an axially-slender axisymmetric filament and no fluid inertia. The computational results motivate a similarity transformation and we obtain a new self-similar solution in which the second-order stress is balanced by capillarity. The new asymptotic solution leads to a self-similar filament shape that is more slender than the Newtonian counterpart and, close to singularity, results in a quadratic dependence of the mid-point radius of the filament with time to breakup. A new and distinct asymptotic geometric correction factor, <span><math><mrow><mi>X</mi><mo>≈</mo><mn>0</mn><mo>.</mo><mn>5827</mn></mrow></math></span> is derived and we show that a more accurate value of the true extensional viscosity in a rate-thickening fluid can be recovered from an interpolated time-varying geometric correction factor based on the magnitudes of different stress components. Finally, we propose a statistically data-driven protocol to select the best-fit constitutive model using a parameter-free information criterion. This enables us to more accurately quantify the extensional rheological behavior of complex rate-thickening viscoelastic fluids using capillarity-driven thinning dynamics.</p></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"331 ","pages":"Article 105294"},"PeriodicalIF":2.7,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141865149","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}