Journal of Non-Newtonian Fluid Mechanics最新文献_第2页

Dimensional analysis and the validation by molecular dynamics simulation of polymer melt flow

IF 2.7 2区工程技术

Journal of Non-Newtonian Fluid Mechanics Pub Date : 2025-02-01 DOI: 10.1016/j.jnnfm.2024.105375

Jinrong Zhang , Dadong Yan , Li Peng , Xianbo Huang

{"title":"Dimensional analysis and the validation by molecular dynamics simulation of polymer melt flow","authors":"Jinrong Zhang , Dadong Yan , Li Peng , Xianbo Huang","doi":"10.1016/j.jnnfm.2024.105375","DOIUrl":"10.1016/j.jnnfm.2024.105375","url":null,"abstract":"<div><div>As well known, in the simulation process of wind tunnel, as long as the Reynolds number is kept constant, a small-sized model wing can be used to simulate a large-sized real wing and obtain similar flow fields. We draw inspiration from it that in the flow of viscoelastic fluid, such as the process of polymer melt injection, the mold corresponds to a wind tunnel, and there is also a flow field. Since the polymer melt is a viscoelastic fluid and is different from air, there should be another physical quantity corresponding to the Reynolds number. By dimensional analysis, we find that it is the Weissenberg number, <span><math><mrow><mi>W</mi><mi>i</mi></mrow></math></span> <span><math><mrow><mo>(</mo><mo>=</mo><mi>v</mi><mi>τ</mi><mo>/</mo><mi>z</mi><mo>)</mo></mrow></math></span>. If <span><math><mrow><mi>W</mi><mi>i</mi></mrow></math></span> remains constant, changing the injection speed <span><math><mi>v</mi></math></span>, changing the relaxation time of the polypropylene melt <span><math><mi>τ</mi></math></span>, or changing the size of the mold <span><math><mi>z</mi></math></span> will result in a similar geometric shape of the flow field. In fact, changing the size of the mold in polymer processing is not an easy task. Therefore, we first conduct mesoscopic scale dimensional analysis and then perform mesoscopic scale molecular dynamics simulation. The simulation results verify the conclusion of the dimensional analysis, so we have reason to believe that the conclusion is correct at the macroscopic scale, and we expect to verify it in the future by changing the mold size and injection speed. In the future, we will use this method to understand the flow of polymer melt in the mold, which may enhance our understanding of melt flow instability within the mold.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"336 ","pages":"Article 105375"},"PeriodicalIF":2.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143154450","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}

引用次数: 0

Particulate suspensions with capillary force: The micropolar fluid theory approach

IF 2.7 2区工程技术

Journal of Non-Newtonian Fluid Mechanics Pub Date : 2025-02-01 DOI: 10.1016/j.jnnfm.2025.105382

Vladimir Shelukhin

引用次数: 0

The movement of particles in Taylor–Couette flow of complex fluids

IF 2.7 2区工程技术

Journal of Non-Newtonian Fluid Mechanics Pub Date : 2025-01-01 DOI: 10.1016/j.jnnfm.2024.105354

Andrew Clarke, Mahdi Davoodi

{"title":"The movement of particles in Taylor–Couette flow of complex fluids","authors":"Andrew Clarke, Mahdi Davoodi","doi":"10.1016/j.jnnfm.2024.105354","DOIUrl":"10.1016/j.jnnfm.2024.105354","url":null,"abstract":"<div><div>A drilling process comprises a drill-pipe rotating within a borehole where fluid is pumped down the pipe and returns, with drilled cuttings, along the annulus. Predominantly the axis of the system is horizontal. Thus, in the absence of axial flow the process geometry is that of a Taylor–Couette flow. Formulated drilling fluids themselves are usually regarded as Bingham or Hershel-Bulkley in nature, but nevertheless encompass elastic behaviour. We have thus studied the distribution of dense (i.e. sedimenting) non-Brownian solid particles in Taylor–Couette flow of model drilling fluids as a function of center body rotation speed. In all cases Taylor vortices are formed above some critical, fluid dependent, Taylor number. However, depending on the fluid properties, particles decorate the vortices differently: particles in a polymeric fluid move to the centroids of the vortices, whereas in a colloidal fluid they move to the outer periphery of the vortices, as previously observed for Newtonian fluids. With a mixed fluid, a clear transition between the two regimes is found. We postulate that this behaviour is a result of a balance between elastically derived lift forces and inertially driven Saffman lift forces acting antagonistically on the particles.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"335 ","pages":"Article 105354"},"PeriodicalIF":2.7,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143153294","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}

引用次数: 0

Editorial to the Commemorative Special Issue of JNNFM in honour of Professor Ken Walters FRS

IF 2.7 2区工程技术

Journal of Non-Newtonian Fluid Mechanics Pub Date : 2024-12-01 DOI: 10.1016/j.jnnfm.2024.105342

Daniel J. Curtis, Francesco Del Giudice, Karl M. Hawkins

引用次数: 0

A lattice Boltzmann flux solver with log-conformation representation for the simulations of viscoelastic flows at high Weissenberg numbers 高Weissenberg数下粘弹性流动模拟的对数构象晶格玻尔兹曼通量求解器

IF 2.7 2区工程技术

Journal of Non-Newtonian Fluid Mechanics Pub Date : 2024-11-26 DOI: 10.1016/j.jnnfm.2024.105351

Hua Zhang , Chang Shu , Lian-Ping Wang , Yaguang Liu

{"title":"A lattice Boltzmann flux solver with log-conformation representation for the simulations of viscoelastic flows at high Weissenberg numbers","authors":"Hua Zhang , Chang Shu , Lian-Ping Wang , Yaguang Liu","doi":"10.1016/j.jnnfm.2024.105351","DOIUrl":"10.1016/j.jnnfm.2024.105351","url":null,"abstract":"<div><div>In this work, a viscoelastic lattice Boltzmann flux solver (VLBFS) with log-conformation representation is proposed for simulating the incompressible flows of a viscoelastic fluid at high Weissenberg number conditions. Compared with the original lattice Boltzmann flux solver (LBFS), the present method has two main new features. First, the method solves the polymer constitutive equations with log-conformation representation. Second, an upwind-biased scheme is incorporated in the interpolation when performing flux reconstructions at the cell interface. With the aid of these two treatments, the numerical stability of VLBFS is significantly improved, making it capable of solving high Weissenberg number problems (HWNP). Compared with using the lattice Boltzmann method (LBM) to solve the viscoelastic fluid flow, VLBFS inherits the advantages of LBFS, such as flexible mesh generation, decoupling of the grid spacing and time interval, and low memory requirement. VLBFS can also precisely recover the macroscopic constitutive equation. The present method has been critically validated using three benchmark cases, namely, the plane Poiseuille flow, lid-driven cavity flow, and 4:1 abrupt planar contraction flow. The numerical results fully demonstrate the solver’s powerful ability in simulating HWNP.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"335 ","pages":"Article 105351"},"PeriodicalIF":2.7,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142744985","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}

引用次数: 0

Analysis of the shear thickening behavior of a fumed silica suspension using QL-LAOS approach 气相二氧化硅悬浮液的剪切增厚行为分析

IF 2.7 2区工程技术

Journal of Non-Newtonian Fluid Mechanics Pub Date : 2024-11-26 DOI: 10.1016/j.jnnfm.2024.105355

E. Fernández-Díaz , F.J. Rubio-Hernández , J.F. Velázquez-Navarro

{"title":"Analysis of the shear thickening behavior of a fumed silica suspension using QL-LAOS approach","authors":"E. Fernández-Díaz , F.J. Rubio-Hernández , J.F. Velázquez-Navarro","doi":"10.1016/j.jnnfm.2024.105355","DOIUrl":"10.1016/j.jnnfm.2024.105355","url":null,"abstract":"<div><div>The feasibility of applying quasi-linear large amplitude oscillatory shear (QL-LAOS) approach to a shear thickening (ST) fumed silica suspension was tested. While the characteristic time has been used as the parameter for the original QL-LAOS analysis of shear thinning fluids, we obtained that a description based upon increasing stiffness is more appropriate for ST fumed silica suspensions. Very low <span><math><mrow><mo>(</mo><mrow><mo>≤</mo><mn>1.5</mn></mrow><mo>)</mo></mrow></math></span> third to first harmonics ratio were obtained indicating the need of alternative criteria to identify QL-LAOS behavior in ST suspensions. Consequently, a method based upon the best fit of an ellipse to the experimental Lissajous-Bowditch curves was proposed. Compliances were obtained from areas of viscous and elastic fitted ellipses. The dependence of the material functions obtained by using a Jeffrey´s mechanical viscoelastic framework with angular frequency supports the idea of ST microstructure evolves by increasing with shear the number of small hydroclusters.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"335 ","pages":"Article 105355"},"PeriodicalIF":2.7,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142744986","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}

引用次数: 0

The influence of thixotropy on bubble growth in thixotropic yield stress fluids: Insights from numerical simulations 触变性对触变性屈服应力流体中气泡生长的影响：来自数值模拟的见解

IF 2.7 2区工程技术

Journal of Non-Newtonian Fluid Mechanics Pub Date : 2024-11-19 DOI: 10.1016/j.jnnfm.2024.105353

Yixuan Hou , Zhao Jin , Xinzhe Que , Yongchao Zhou , Yiping Zhang

{"title":"The influence of thixotropy on bubble growth in thixotropic yield stress fluids: Insights from numerical simulations","authors":"Yixuan Hou , Zhao Jin , Xinzhe Que , Yongchao Zhou , Yiping Zhang","doi":"10.1016/j.jnnfm.2024.105353","DOIUrl":"10.1016/j.jnnfm.2024.105353","url":null,"abstract":"<div><div>Bubble behaviors in structured fluids are of great interests in industrial applications, while there is currently a lack of understanding regarding the effect of thixotropic microstructure on the bubble formation process. To this end, this study explores the influence of thixotropy on bubble growth in thixotropic yield stress fluids by numerical simulations using the Arbitrary Lagrangian-Eulerian (ALE) method. The numerical results reveal that, with the increase in the thixotropy number, the bubbles at detachment transform from inverted conical to spherical shapes at lower gas flow rates, and from spindle to conical shapes at higher gas flow rates, along with the decreased detachment volume and time. It is also found that the effect of gas flow rate varies with different thixotropy numbers. The flow field of the structured fluid reveals that the increases in gas flow rate primarily promote the structural destruction near the bubble tip, while the increase in thixotropy number facilitate the fluid flow around the bubble, with the significant reduction of the low-shear zones and expansion of the yielded zones near the equatorial plane. As a result, modulating the fluid flow with thixotropy number mainly influences the hydrodynamic pressure on the bubble. Based on a force balance model, the forces acting on the bubble are then calculated by integrating the stress on the interface, and it is found that thixotropy number controls the bubble detachment state with the drag effect. Accordingly, the mechanisms governing the influence of thixotropy on drag effect are discussed considering the flow field characteristics and the correlations of drag coefficients. This work helps to deepen the understanding of the bubble behaviors in structured fluids.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"335 ","pages":"Article 105353"},"PeriodicalIF":2.7,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142744983","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}

引用次数: 0

Suppression and augmentation in vortex shedding frequency due to fluid elasticity 流体弹性对旋涡脱落频率的抑制和增强

IF 2.7 2区工程技术

Journal of Non-Newtonian Fluid Mechanics Pub Date : 2024-11-19 DOI: 10.1016/j.jnnfm.2024.105348

A. Chauhan, Sana Raffi, C. Sasmal

{"title":"Suppression and augmentation in vortex shedding frequency due to fluid elasticity","authors":"A. Chauhan, Sana Raffi, C. Sasmal","doi":"10.1016/j.jnnfm.2024.105348","DOIUrl":"10.1016/j.jnnfm.2024.105348","url":null,"abstract":"<div><div>Several previous experimental and numerical studies have demonstrated the suppression of vortex shedding frequency from bluff bodies, such as circular cylinders, due to fluid elasticity induced by adding solid polymer additives to a solvent like water, even in parts per million (ppm) quantities. However, this study reveals a more complex relationship between the two using extensive two-dimensional (2D) direct numerical simulations (DNS) of flows past a circular cylinder at a fixed Reynolds number of 100. Our findings show that the vortex shedding frequency initially decreases with increasing Weissenberg number (a measure of fluid elasticity), reaches a minimum at a critical Weissenberg number, and then increases with further increments in the Weissenberg number. The same non-monotonic trend is also observed in the temporal variation of the spanwise velocity component fluctuation within the flow domain. This study aims to elucidate the reasons behind these non-monotonic trends in vortex shedding frequency and velocity component fluctuations as functions of the Weissenberg number. Our detailed analysis attributes these trends to significant alterations in the vortex-shedding mechanism as fluid elasticity increases due to the appearance of inertio-elastic instability at higher Weissenberg numbers. Our findings also align with limited experimental observations of similar unexpected behaviors in viscoelastic fluids, providing new insights into the underlying mechanisms. Moreover, the study highlights that shear-thinning behavior in viscoelastic fluids counteracts these non-monotonic trends, instead promoting a monotonic increase in vortex shedding frequency with the Weissenberg number. Finally, the 2D simulation results show both qualitative and quantitative agreement with limited three-dimensional (3D) simulations conducted at higher Weissenberg numbers where the flow may transit from 2D to 3D due to the appearance of inertio-elastic instability.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"335 ","pages":"Article 105348"},"PeriodicalIF":2.7,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142744982","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}

引用次数: 0

Viscoelastic model hierarchy for fiber melt spinning of semi-crystalline polymers 半结晶聚合物纤维熔融纺丝的粘弹性模型层次

IF 2.7 2区工程技术

Journal of Non-Newtonian Fluid Mechanics Pub Date : 2024-11-16 DOI: 10.1016/j.jnnfm.2024.105349

Manuel Ettmüller , Walter Arne , Nicole Marheineke , Raimund Wegener

{"title":"Viscoelastic model hierarchy for fiber melt spinning of semi-crystalline polymers","authors":"Manuel Ettmüller , Walter Arne , Nicole Marheineke , Raimund Wegener","doi":"10.1016/j.jnnfm.2024.105349","DOIUrl":"10.1016/j.jnnfm.2024.105349","url":null,"abstract":"<div><div>In the fiber melt spinning of semi-crystalline polymers, the degree of crystallization can be non-homogeneous over the cross-section of the fiber, affecting the properties of the end product. For simulation-based process design, the question arises as to which fiber quantities and hence model equations must be resolved in radial direction to capture all practically relevant effects and at the same time imply a model that can be computed with reasonable effort. In this paper, we present a hierarchy of viscoelastic two-phase fiber models ranging from a complex, fully resolved and highly expensive three-dimensional description to a cross-sectionally averaged, cheap-to-evaluate one-dimensional model. In particular, we propose a novel stress-averaged one-two-dimensional fiber model, which circumvents additional assumptions on the inlet profiles needed in the established stress-resolved fiber model by Doufas et al. (2001). Simulation results demonstrate the performance and application regime of the dimensionally reduced models. The novel stress-averaged variant provides fast and reliable results, especially in the regime of low flow-enhanced crystallization.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"335 ","pages":"Article 105349"},"PeriodicalIF":2.7,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142744981","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}

引用次数: 0

Enhancing polymer fiber orientation with 3D-printed shell–core structures 3d打印壳核结构增强聚合物纤维取向

IF 2.7 2区工程技术

Journal of Non-Newtonian Fluid Mechanics Pub Date : 2024-11-15 DOI: 10.1016/j.jnnfm.2024.105352

Mengfan Lou, Zhenyu Ouyang

{"title":"Enhancing polymer fiber orientation with 3D-printed shell–core structures","authors":"Mengfan Lou, Zhenyu Ouyang","doi":"10.1016/j.jnnfm.2024.105352","DOIUrl":"10.1016/j.jnnfm.2024.105352","url":null,"abstract":"<div><div>This study numerically investigates the flow dynamics and fiber orientation in enhanced polymer shell–core structures during 3D printing using the smoothed particle hydrodynamics method. A microstructure-based fiber suspension model, coupled with a shear-thinning viscosity model, is employed to assess the effects of varying material viscosities, fiber aspect ratios and volume fractions, and substrate speeds on fiber orientation distribution. Our results demonstrate that fiber orientation in deposited layers is particularly sensitive to variations in the viscosity of the shell material, while changes in the core material viscosity have a smaller and more localized impact on fiber orientation. Furthermore, fiber orientation is strongly influenced by the product of the fiber aspect ratio <em>α<sub>r</sub></em> and volume fraction <em>ϕ</em>; as <em>α<sub>r</sub>ϕ</em> increases, fibers tend to align with the flow direction of materials. However, adjusting the fiber aspect ratio and volume fraction while maintaining the same <em>α<sub>r</sub>ϕ</em> results in slight changes to fiber alignment. Additionally, lower substrate speeds cause upstream material accumulation, increasing deposition layer height and creating differences in fiber orientation between the core and shell regions. An appropriate increase in substrate speed can mitigate these effects.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"335 ","pages":"Article 105352"},"PeriodicalIF":2.7,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142745105","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}

引用次数: 0