Journal of Non-Newtonian Fluid Mechanics最新文献

{"title":"Tricritical state and quasi-periodicity triggered by the non-linear elasticity in an Upper Convected Maxwell fluid confined between two co-oscillating cylinders about zero-mean","authors":"Mohamed Hayani Choujaa ,&nbsp;Mehdi Riahi ,&nbsp;Saïd Aniss","doi":"10.1016/j.jnnfm.2024.105202","DOIUrl":"https://doi.org/10.1016/j.jnnfm.2024.105202","url":null,"abstract":"<div><p>The effects of harmonically co-oscillating the inner and outer cylinders about zero mean rotation in a Taylor–Couette flow are examined numerically using Floquet theory, for the case where the fluid confined between the cylinders obeys the upper convected Maxwell model. Although stability diagrams and mode competition involved in the system were clearly elucidated recently by Hayani Choujaa et al. (2021) in weakly elastic fluids, attention is focused, in this paper, on the dynamic of the system at higher elasticity with emphasis on the nature of the primary bifurcation. In this framework, we are dealing with pure inertio-elastic parametric resonant instabilities where the elastic and inertial mechanisms are considered of the same order of magnitude. It turns out, on the one hand, that the fluid elasticity gives rise, at the onset of instability, to the appearance of a family of new harmonic modes having different axial wavelengths and breaking the spatio-temporal symmetry of the base flow: invariance in the axial direction generating the <span><math><mrow><mi>O</mi><mrow><mo>(</mo><mn>2</mn><mo>)</mo></mrow></mrow></math></span> symmetry group and a half-period-reflection symmetry in the azimuthal direction generating a spatio-temporal <span><math><msub><mrow><mi>Z</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> symmetry group. On the other hand, new quasi-periodic flow emerging in the high frequency limit and other interesting bifurcation phenomena including bi and tricritical states are also among the features induced by the fluid elasticity. Lastly, and in comparison with the Newtonian configuration of this system, the fluid elasticity leads to a total suppression of the non-reversing flow besides emergence of instabilities with lower wavelengths. Such a comparison provides insights into the dynamics of elastic hoop stresses in altering the flow reversal in modulated Taylor–Couette flow.</p></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"325 ","pages":"Article 105202"},"PeriodicalIF":3.1,"publicationDate":"2024-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139732936","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":"Mist-control of polyalphaolefin (PAO) lubricants using long pairwise end-associative polymers","authors":"Red C. Lhota ,&nbsp;Robert W. Learsch ,&nbsp;Jacob Temme ,&nbsp;Vincent Coburn ,&nbsp;Julia A. Kornfield","doi":"10.1016/j.jnnfm.2024.105197","DOIUrl":"10.1016/j.jnnfm.2024.105197","url":null,"abstract":"<div><p>Accidental release of pressurized hydrocarbon fuels and lubricants are a major fire hazard due to the formation of small droplet mists that can readily evaporate and ignite. Mist control through increasing droplet size and suppressing droplets has been previously demonstrated with high molecular weight polymer additives, but traditional long polymer additives do not survive the pumping that would usually precede accidental release. This constraint inspired associative polymer additives that can transiently form the high molecular weights needed for mist control, while reversibly breaking during pumping. A prior study demonstrated the efficacy of such a system in fuel: long telechelic polycyclooctadiene (PCOD) with pairwise associating acid and base end-groups. Here, we address an obstacle to applying this same polymeric system in a polyalphaolefin (PAO) solvent—its poorer solvent quality for PCOD than fuel. We measured the effects of the end-associative PCOD compared to a non-associative control on the rheological properties of solutions in both PAO (a common lubricant and heat transfer fluid) and decahydronapthalene (decalin, a solvent with PCOD solubility similar to fuel) in shear and extension, and connect those rheological modifications to observed changes in PAO spray under simulated accidental release conditions. The PCOD additives demonstrated substantial mist control in PAO, both in terms of reduced spray angle and droplet suppression. Despite the worse solubility in PAO and thus smaller effective coil size, these associative PCOD additives are effective at the low concentrations (¡0.1 wt %) necessary for practical use as a safety measure.</p></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"326 ","pages":"Article 105197"},"PeriodicalIF":3.1,"publicationDate":"2024-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0377025724000132/pdfft?md5=7ee72566e506e91fc25e1f654f0b3eaf&pid=1-s2.0-S0377025724000132-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139890989","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":"The elastic perfectly plastic constitutive equation for yield stress fluids","authors":"Kamil Fedorowicz,&nbsp;Robert Prosser","doi":"10.1016/j.jnnfm.2024.105201","DOIUrl":"https://doi.org/10.1016/j.jnnfm.2024.105201","url":null,"abstract":"<div><p>We explore the use of an <em>Elastic Perfectly Plastic</em> (EPP) constitutive equation for the modelling of yield stress fluids. Contrary to many other models, stresses in the EPP model arise from elastic deformation rather than as a viscous effect. In this paper, the EPP model is coupled to a standard viscous treatment of the post-yield flow stresses to produce Bingham-like behaviour, and the timescale associated with the yielding mechanism is linked to material parameters. We also show that when the yield stress is much smaller than the elastic modulus, EPP and Bingham models can produce very similar flow fields in channel and contraction geometries. The EPP model is found to be significantly cheaper computationally in both geometries. Additionally, in the case of channel flow where analytical solutions exist, the EPP model is associated with a much smaller error than the regularised Bingham model.</p></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"325 ","pages":"Article 105201"},"PeriodicalIF":3.1,"publicationDate":"2024-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S037702572400017X/pdfft?md5=205eab5204c7171449d25e6304b4ce53&pid=1-s2.0-S037702572400017X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139738184","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":"Mixing in heterogeneous fluids: An examination of fluid property variations","authors":"Mohammad Reza Daneshvar Garmroodi,&nbsp;Ida Karimfazli","doi":"10.1016/j.jnnfm.2024.105196","DOIUrl":"https://doi.org/10.1016/j.jnnfm.2024.105196","url":null,"abstract":"&lt;div&gt;&lt;p&gt;In the context of stirred tanks, “mixing” refers to the purposeful and controlled flow designed to minimize heterogeneity, such as variations in solute or additive concentration. Industries like food and polymer processing often encounter situations where fluid properties are closely tied to additive concentration. However, conventional engineering models of mixing, herein referred to as “homogeneous models”, typically assume that the influence of heterogeneous fluid properties on mixing dynamics is negligible. In these models, flow development is considered independent of mixing, and the fluid’s rheological properties and density are assumed to be uniform. This manuscript’s primary objective is to emphasize the potential for substantial inaccuracies in predicting mixing outcomes when the effects heterogeneous fluid properties are disregarded. We investigate the homogenization of an additive in a fluid-filled cylindrical tank stirred by an axisymmetric disk, where both fluid rheology and density are contingent on the additive concentration. We introduce and compare two models for predicting mixing development. The first model (model problem &lt;span&gt;&lt;math&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;) incorporates variations in fluid properties dependent on the additive concentration, while the second model (model problem &lt;span&gt;&lt;math&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;) simplifies the fluid properties to their average values. Our approach to modeling mixing centers on a concentration field governed by advection–diffusion. We illustrate that the mapping between the parameter spaces of the two model problems is far from one-to-one. For any given point in the parameter space of model problem &lt;span&gt;&lt;math&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;, three distinct parameter groups (buoyancy, Atwood number, and viscosity ratio) exhibit unconstrained variations within the corresponding subset of the parameter space of model problem &lt;span&gt;&lt;math&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;. As a concrete example, we investigate the impact of buoyancy on the evolution of velocity and additive concentration in model problem &lt;span&gt;&lt;math&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;. Our analysis characterizes the influence of buoyancy on the mixing rate by examining the asymptotic behavior of the concentration field. We find that the standard deviation of the concentration asymptotically converges to an exponential decay, with the intercept and decay rate diminishing as a power-law function of buoyancy. This underscores the significant effect that even slight variations in buoyancy can have on the mixing process. Finally, our results conclusively demonstrate that the recirculation zones, areas where fluid velocity is notable, in model problems &lt;em&gt;M&lt;/em&gt; and &lt;em&gt;T&lt;/em&gt; do not align. In model problem &lt;span&gt;&lt;math&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;, the well-mixed region and the recirculation zones closely coincide, but this alignment is not observed in model problem &lt;span&gt;&lt;math&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;. Collectively, our study provides a counterexample th","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"325 ","pages":"Article 105196"},"PeriodicalIF":3.1,"publicationDate":"2024-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139738186","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 multiscale framework for polymer modeling applied in a complex fluid flow","authors":"Kosar Khajeh,&nbsp;Deboprasad Talukdar,&nbsp;Gentaro Sawai,&nbsp;Hitoshi Washizu","doi":"10.1016/j.jnnfm.2024.105200","DOIUrl":"10.1016/j.jnnfm.2024.105200","url":null,"abstract":"<div><p>Understanding polymer dynamics under shear flow is crucial for studying their rheological behavior in diverse applications. However, conventional micro analyses provide limited insights into polymer elongation and conformation. To address this, we propose a hybrid model combining the Lattice Boltzmann method and Langevin Dynamics technique, which captures the multiscale nature of polymer dynamics. Using the coarse-grain bead-spring method, we optimize computational efficiency and model polymers as chains with specific mass and charge. Our hybrid model integrates Navier-Stokes equations with external drag force modified based on segment velocities from Brownian Dynamics simulations.</p><p>In our study, we investigated the effects of chain structure and solvent properties on polymer solutions under shear flow through numerical simulations. We observed that in high shear rate flows, a viscous solvent promotes polymer elongation, while low shear rate flows lead to chain insolubility in the base oil. Longer chains have a greater overall impact on the fluid due to increased contact points with the solvent. The size of the polymer coil over time is influenced by shear rate, chain length, and solvent viscosity. Moreover, solvent density, particle mass, and radius locally affect fluid flow. The higher viscosity fluids result in amplified hydrodynamic and random forces acting on the chains. These findings have implications for applications involving polymer additives that alter the properties of the host solvent in natural and artificial processes. Our study represents an initial step towards a comprehensive understanding of polymer dynamics, taking into account the diverse factors that influence them.</p></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"325 ","pages":"Article 105200"},"PeriodicalIF":3.1,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139892762","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 steady and unsteady regimes in a cubic lid-driven cavity with viscoplastic fluid solved with the lattice Boltzmann method","authors":"Marco A. Ferrari,&nbsp;Admilson T. Franco","doi":"10.1016/j.jnnfm.2024.105198","DOIUrl":"10.1016/j.jnnfm.2024.105198","url":null,"abstract":"<div><p>This work builds upon the previously published analysis of a lid-driven cavity filled with viscoplastic fluid. We extend the study from a two-dimensional case to a three-dimensional one, employing the moment representation of the lattice Boltzmann method to obtain numerical results. The findings expand the existing dataset, which can potentially serve as benchmark results for inertial regimes of viscoplastic flows. In this study, we investigate the Reynolds and Bingham numbers until the flow transition from stationary to a transient regime. The results reveal that, similarly to the Newtonian case, there is an effective Reynolds number for the bifurcation, approximately Re^⁎ = Re₀ (1 + Bn), where Re₀ represents the bifurcation point for a Newtonian fluid. Like the Newtonian cases, there were instances where the Taylor-Görtler-like vortices moved toward the cavity's side periodically. In other cases, more than two vortices simultaneously formed, with their number changing over time. Finally, similar to the two-dimensional case, the bifurcation initiated after the Moffat eddies in the downstream corner broke down into plugs.</p></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"325 ","pages":"Article 105198"},"PeriodicalIF":3.1,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139664956","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":"Multiscale simulations for polymer melt spinning process using Kremer–Grest CG model and continuous fluid mechanics model","authors":"Yan Xu,&nbsp;Yuji Hamada,&nbsp;Takashi Taniguchi","doi":"10.1016/j.jnnfm.2024.105195","DOIUrl":"10.1016/j.jnnfm.2024.105195","url":null,"abstract":"<div><p>We succeeded in developing a <u>m</u>ulti<u>s</u>cale <u>s</u>imulation (MSS) method for a spinning process of a polymer melt. A previous work by Sato and Taniguchi (2017) developed a MSS method where the microscopic model and macroscopic model for the spinning process are respectively modeled by using a slip-link model and a continuous fluid mechanics model. Here we replace the microscopic model with the Kremer–Grest <u>c</u>oarse-<u>g</u>rained (CG) model, and investigate the state of the polymer chains at steady state in the spinning process, by changing the <u>d</u>raw <u>r</u>atio <span>Dr</span>. Unlike the previous MSS, where the microscopic simulator is a slip-link model, in which polymer chains are simulated in virtual space and entanglements are treated by virtual links, in the present MSS, a real space molecular dynamics simulator is used as the microscopic simulator. The replacement brings the advantage that we can obtain more information on the state of polymer chains, but also brings two computational difficulties, (I) the requirement of a huge computational cost, and (II) the simulation box problem related to the periodic boundary condition in the microscopic system. To deal with (I), we considered a micro-macro coupling method different from previous MSS. To resolve problem (II), we used the UEF (uniform extensional flow) method developed by Nicholson and Rutledge (2016) and Murashima et al. (2018) for a polymer melt system. By using these two ideas, we performed MSS simulations, and established a correspondence between the macroscopic flow and the microscopic polymer conformations at any position along the spinning line. Furthermore, we investigated the influence of <span>Dr</span> on the stretching and orientation of polymers chains and the spatial correlation between polymer chains.</p></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"325 ","pages":"Article 105195"},"PeriodicalIF":3.1,"publicationDate":"2024-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139649109","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":"Elastoviscoplasticity intensifies the unstable flows through a micro-contraction geometry","authors":"A. Chauhan,&nbsp;C. Sasmal","doi":"10.1016/j.jnnfm.2024.105186","DOIUrl":"10.1016/j.jnnfm.2024.105186","url":null,"abstract":"<div><p><span>This study focuses on the two-dimensional numerical investigation of complex fluid flows through a micro-contraction geometry in the creeping flow<span> regime, specifically examining elastoviscoplastic (EVP) fluids. These fluids exhibit a combination of viscous, elastic, and plastic behaviors. The governing equations, including mass and momentum, are solved using a finite volume method-based discretization technique. Saramito’s constitutive model is utilized to accurately represent the viscous, elastic, and plastic responses of the EVP fluid. The present results demonstrate significant differences in flow dynamics, such as vortex dynamics and transitions between flow regimes (e.g., steady to unsteady), when compared to simple Newtonian and non-Newtonian viscoelastic (VE) or viscoplastic (VP) fluids. This study reveals that when the yield strain </span></span><span><math><mrow><mo>(</mo><msub><mrow><mi>ϵ</mi></mrow><mrow><mi>y</mi></mrow></msub><mo>)</mo></mrow></math></span><span><span> exceeds a critical value, approximately ranging from 0.79 to 0.89, the flow transits from a steady to an unsteady state for the EVP fluids. Importantly, the present study shows that EVP fluids exhibit intensified chaotic flow dynamics and increased instability compared to VE and VP fluids under similar flow conditions. However, the presence of shear-thinning behavior in EVP fluids suppresses this instability. The analysis of local velocity fields<span> and flow deformation in this study highlights the impact on the stretching of fluid microstructure and </span></span>elastic stresses<span>, which ultimately contribute to the origin of this intensified unstable flow condition for EVP fluids. The finding from this study holds significant potential for enhancing heat or mass transfer rates and mixing efficiency in micro-scale systems, where the prevailing steady and laminar flow conditions often hinder these transport processes.</span></span></p></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"325 ","pages":"Article 105186"},"PeriodicalIF":3.1,"publicationDate":"2024-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139507598","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":"Quantitative description of polymer drag reduction: Effect of polyacrylamide molecular weight distributions","authors":"Lukas Brandfellner ,&nbsp;Emina Muratspahić ,&nbsp;Alexander Bismarck ,&nbsp;Hans Werner Müller","doi":"10.1016/j.jnnfm.2024.105185","DOIUrl":"10.1016/j.jnnfm.2024.105185","url":null,"abstract":"<div><p>The effect of molecular weight distribution of polyacrylamide (PAAm) on drag reduction was studied in two flow geometries. Commercial PAAm with different weight averaged molecular weights (<em>M_w</em> = 5 × 10⁵ to 1.8 × 10⁷ g/mol) were investigated in turbulent pipe and rotational flows. Comparison of PAAm with different molecular weight distributions showed that drag reduction is not only a function of the averaged molecular weight. Broader polymer molecular weight distributions provided increased drag reduction over polymers of same average molecular weight but with a more narrow distribution. The role of distribution widths is of significance as polymer degradation in turbulent flows causes narrowing of the molecular weight distributions. Multiple linear regression was employed to connect weight fractions of polyacrylamide with drag reduction. Multiple linear regression was successfully applied to describe drag reduction in turbulent pipe and rotational flows indicating that drag reduction can be quantitatively derived from the molecular weight distribution of PAAm.</p></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"325 ","pages":"Article 105185"},"PeriodicalIF":3.1,"publicationDate":"2024-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0377025724000016/pdfft?md5=2ffcdea18b7ec24eafcb2f2d0179ab47&pid=1-s2.0-S0377025724000016-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139496871","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":"On the use of time-dependent fluids for delaying onset of transition to turbulence in the flat plate boundary-layer flow: A passive control of flow","authors":"Danial Rezaee","doi":"10.1016/j.jnnfm.2023.105184","DOIUrl":"10.1016/j.jnnfm.2023.105184","url":null,"abstract":"<div><p><span>Inelastic time-dependent fluids display continuous and reversible changes in viscosity when subjected to a constant shear-rate. These alterations arise from the gradual modification of the material’s microstructure due to shear-induced effects, known as shear rejuvenation. When this process generates smaller structural units, it is termed thixotropy; conversely, if it produces larger units, it is labeled anti-thixotropy. Aging is another characteristic of such fluids, denoting the capacity of the material to regain its original structure in the absence of shear, thus reversing the initial time-dependent change. This phenomenon often results from thermally activated Brownian motion prompting the reorganization of the material’s microconstituents. Consequently, attractive forces between these components can instigate the reconstruction of a network-like structure within the material. This study centers on investigating how variations in fluid microstructure impact the onset of transition to turbulence in a flat plate boundary-layer flow. Specifically, the focus is on cases where larger structural units emerge during the breakdown process (anti-thixotropy). To represent such fluids, the Quemada model, an inelastic structural-kinetic model, is employed. This model effectively captures thixotropy and anti-thixotropy by appropriately configuring model parameters. The analysis begins with obtaining a local similarity solution for the generalized </span>Blasius equation, representing the base flow. Subsequently, the stability of this flow is assessed using linear temporal stability theory. This involves introducing infinitesimally-small normal-mode perturbations to the base flow, yielding the generalized Orr–Sommerfeld equation. Solving this equation using the spectral method provides insights into stability. Results from this study indicate that for low Deborah numbers, the shear-thickening behavior prevails, causing destabilization. In contrast, higher Deborah numbers lead to stability. This implies that anti-thixotropy effectively delays the onset of transition to turbulence and could hold practical applications for flow control.</p></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"324 ","pages":"Article 105184"},"PeriodicalIF":3.1,"publicationDate":"2024-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139096192","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}