Pub Date : 2025-05-14DOI: 10.1016/j.jnnfm.2025.105422
T. Matsuda , M. Muto , S. Tamano
Filaments ejected from a drop-on-demand (DOD) head filled with a dilute polymer solution (PEO, polyethylene oxide) were photographed and analyzed using a high-speed camera. The filament decay was faster at lower PEO concentrations and became nearly identical at extremely low concentrations. The extensional relaxation time decreased with as the PEO concentration decreased following the power law, and approached an almost constant value near the critical concentration , which is close to the theoretical limit. The relationship between the PEO concentration normalized by the overlapping concentration and the relaxation time normalized by the Zimm relaxation time was linear in both logarithmic graphs and independent of molecular weight. The power-law exponent in piezo-driven extensional rheometry is similar to that reported in previous studies, such as those using the liquid dripping (LD) method, capillary breakup extensional rheometry (CaBER), and Rayleigh–Ohnesorge jetting extensional rheometry (ROJER).
{"title":"Extensional properties of dilute polymer solutions with different molecular weights measured using piezo-driven extensional rheometry","authors":"T. Matsuda , M. Muto , S. Tamano","doi":"10.1016/j.jnnfm.2025.105422","DOIUrl":"10.1016/j.jnnfm.2025.105422","url":null,"abstract":"<div><div>Filaments ejected from a drop-on-demand (DOD) head filled with a dilute polymer solution (PEO, polyethylene oxide) were photographed and analyzed using a high-speed camera. The filament decay was faster at lower PEO concentrations and became nearly identical at extremely low concentrations. The extensional relaxation time decreased with as the PEO concentration decreased following the power law, and approached an almost constant value near the critical concentration <span><math><msub><mrow><mi>c</mi></mrow><mrow><mi>min</mi></mrow></msub></math></span>, which is close to the theoretical limit. The relationship between the PEO concentration normalized by the overlapping concentration and the relaxation time normalized by the Zimm relaxation time was linear in both logarithmic graphs and independent of molecular weight. The power-law exponent in piezo-driven extensional rheometry is similar to that reported in previous studies, such as those using the liquid dripping (LD) method, capillary breakup extensional rheometry (CaBER), and Rayleigh–Ohnesorge jetting extensional rheometry (ROJER).</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"341 ","pages":"Article 105422"},"PeriodicalIF":2.7,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144099164","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}
Pub Date : 2025-05-13DOI: 10.1016/j.jnnfm.2025.105430
A.A. Gavrilov , A.V. Shebelev , A.V. Minakov
A continuum model of shear-thinning fluid suspension flow based on suspension balance model is developed. The generalization of the suspension model to the shear-thinning yield stress fluids, obeying the Herschel-Bulkley law, requires taking into account the shear rate amplification effect and modification of the particle drag force. Additionally, the model includes inertial and unsteady particle effects by using the transport equation for relative velocity. To validate the proposed model, pressure-driven laminar flows of suspensions with neutrally buoyant and heavy particles in circular pipes are numerically simulated. The results show that, at certain conditions, the developed model can adequately describe various flow regimes of shear-thinning yield stress fluids with solid particles, from heterogeneous flows with a stationary sediment layer to flows with suspended particles. An important issue for suspension flows with heavy particles is considered - assessment of the particle transport efficiency. Dependencies of some integral characteristics of the flow are considered.
{"title":"Modelling of the pressure-driven tube flow of the shear-thinning fluids with solid particles","authors":"A.A. Gavrilov , A.V. Shebelev , A.V. Minakov","doi":"10.1016/j.jnnfm.2025.105430","DOIUrl":"10.1016/j.jnnfm.2025.105430","url":null,"abstract":"<div><div>A continuum model of shear-thinning fluid suspension flow based on suspension balance model is developed. The generalization of the suspension model to the shear-thinning yield stress fluids, obeying the Herschel-Bulkley law, requires taking into account the shear rate amplification effect and modification of the particle drag force. Additionally, the model includes inertial and unsteady particle effects by using the transport equation for relative velocity. To validate the proposed model, pressure-driven laminar flows of suspensions with neutrally buoyant and heavy particles in circular pipes are numerically simulated. The results show that, at certain conditions, the developed model can adequately describe various flow regimes of shear-thinning yield stress fluids with solid particles, from heterogeneous flows with a stationary sediment layer to flows with suspended particles. An important issue for suspension flows with heavy particles is considered - assessment of the particle transport efficiency. Dependencies of some integral characteristics of the flow are considered.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"341 ","pages":"Article 105430"},"PeriodicalIF":2.7,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144099248","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}
Pub Date : 2025-05-12DOI: 10.1016/j.jnnfm.2025.105421
Steffen M. Recktenwald , Thomas P. John , Amy Q. Shen , Robert J. Poole , Cláudio P. Fonte , Simon J. Haward
This study presents an experimental framework for large amplitude oscillatory extension (LAOE) to investigate nonlinear material properties of complex fluids. Using a microfluidic optimized shape cross-slot extensional rheometer, we generate approximately homogeneous planar extensional flows driven by programmable syringe pumps operating in oscillatory or pulsatile sinusoidal modes. Micro-particle image velocimetry and simultaneous pressure drop measurements are employed to analyze the time-dependent flow field and elastic stress response. For Newtonian fluids, a linear relationship between the applied strain rate and pressure drop is observed across a wide range of oscillation amplitudes and frequencies. In contrast, dilute polymer solutions exhibit significant deviations, with excess pressure drops and divergence between average strain rates along extension and compression axes during the LAOE cycle. By spanning a broad range of Weissenberg and Deborah numbers, we identify unique Lissajous curves and critical conditions for the onset of nonlinearities under oscillatory extension. Numerical simulations, assuming homogeneous flow, underpin the experimental findings, validating the robustness of our microfluidic approach. This study demonstrates the utility of oscillatory extensional flows for probing the nonlinear rheological behavior of soft materials, offering quantitative insights into their extensional properties under nonlinear flow conditions.
{"title":"Large amplitude oscillatory extension (LAOE) of dilute polymer solutions","authors":"Steffen M. Recktenwald , Thomas P. John , Amy Q. Shen , Robert J. Poole , Cláudio P. Fonte , Simon J. Haward","doi":"10.1016/j.jnnfm.2025.105421","DOIUrl":"10.1016/j.jnnfm.2025.105421","url":null,"abstract":"<div><div>This study presents an experimental framework for large amplitude oscillatory extension (LAOE) to investigate nonlinear material properties of complex fluids. Using a microfluidic optimized shape cross-slot extensional rheometer, we generate approximately homogeneous planar extensional flows driven by programmable syringe pumps operating in oscillatory or pulsatile sinusoidal modes. Micro-particle image velocimetry and simultaneous pressure drop measurements are employed to analyze the time-dependent flow field and elastic stress response. For Newtonian fluids, a linear relationship between the applied strain rate and pressure drop is observed across a wide range of oscillation amplitudes and frequencies. In contrast, dilute polymer solutions exhibit significant deviations, with excess pressure drops and divergence between average strain rates along extension and compression axes during the LAOE cycle. By spanning a broad range of Weissenberg and Deborah numbers, we identify unique Lissajous curves and critical conditions for the onset of nonlinearities under oscillatory extension. Numerical simulations, assuming homogeneous flow, underpin the experimental findings, validating the robustness of our microfluidic approach. This study demonstrates the utility of oscillatory extensional flows for probing the nonlinear rheological behavior of soft materials, offering quantitative insights into their extensional properties under nonlinear flow conditions.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"342 ","pages":"Article 105421"},"PeriodicalIF":2.7,"publicationDate":"2025-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144114847","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}
Pub Date : 2025-05-09DOI: 10.1016/j.jnnfm.2025.105434
Pengfei Shi , Haibao Hu , Jun Wen , Hailang Sun , Luo Xie
An experimental investigation is conducted to characterize the drag reduction of Polyethylene Oxide solutions and its influencing on turbulent pipe flow with polymer injection. The study systematically examines the effects of Reynolds number, injection angle (seven angles), molecular weight (seven molecular weights), and streamwise direction development on drag reduction. Similar to the dimensionless polymer flux K in the flat plate boundary layer flow with polymer injection, the normalized polymer flux Kp applicable to the pipe (i.e., the relative mass ratio between the injecting polymer and the main flow) is defined to further collapse experimental data. The Kp-scaling laws indicate that DR firstly grows linearly, and then saturates or even declines with increasing log10Kp, similar to the observed DR variation of the plate boundary layer flow with polymer injection. The DR vs Kp relationship could provide guidance to optimize the use of polymer injection for the pipeline flow. Notably, the variation law of drag reduction with molecular weight conforms to S-shaped curve, which can provide guidance to optimize the use of molecular weight in polymers drag reduction. The change in drag reduction with Reynolds number varying from 15,952 to 79,761 initially increases and then decreases; there exists a critical Reynolds number for achieving optimal drag reduction effect. The variation of drag reduction rate with injection angle and streamwise direction distance is influenced by both effective concentration and advection of the injected solution. Smaller injection angle does not bring more significant drag reduction effect. Meanwhile, the counter-stream injection exhibits a superior drag reduction effect compared to streamwise injection under certain conditions, primarily due to the influence of more suitable mixing rate.
{"title":"Experimental investigation on drag reduction in turbulent pipe flow with polymer injection","authors":"Pengfei Shi , Haibao Hu , Jun Wen , Hailang Sun , Luo Xie","doi":"10.1016/j.jnnfm.2025.105434","DOIUrl":"10.1016/j.jnnfm.2025.105434","url":null,"abstract":"<div><div>An experimental investigation is conducted to characterize the drag reduction of Polyethylene Oxide solutions and its influencing on turbulent pipe flow with polymer injection. The study systematically examines the effects of Reynolds number, injection angle (seven angles), molecular weight (seven molecular weights), and streamwise direction development on drag reduction. Similar to the dimensionless polymer flux <em>K</em> in the flat plate boundary layer flow with polymer injection, the normalized polymer flux <em>K</em><sub><em>p</em></sub> applicable to the pipe (i.e., the relative mass ratio between the injecting polymer and the main flow) is defined to further collapse experimental data. The <em>K</em><sub><em>p</em></sub>-scaling laws indicate that DR firstly grows linearly, and then saturates or even declines with increasing log<sub>10</sub> <em>K</em><sub><em>p</em></sub>, similar to the observed DR variation of the plate boundary layer flow with polymer injection. The DR vs <em>K</em><sub><em>p</em></sub> relationship could provide guidance to optimize the use of polymer injection for the pipeline flow. Notably, the variation law of drag reduction with molecular weight conforms to S-shaped curve, which can provide guidance to optimize the use of molecular weight in polymers drag reduction. The change in drag reduction with Reynolds number varying from 15,952 to 79,761 initially increases and then decreases; there exists a critical Reynolds number for achieving optimal drag reduction effect. The variation of drag reduction rate with injection angle and streamwise direction distance is influenced by both effective concentration and advection of the injected solution. Smaller injection angle does not bring more significant drag reduction effect. Meanwhile, the counter-stream injection exhibits a superior drag reduction effect compared to streamwise injection under certain conditions, primarily due to the influence of more suitable mixing rate.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"341 ","pages":"Article 105434"},"PeriodicalIF":2.7,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144072381","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}
Pub Date : 2025-05-05DOI: 10.1016/j.jnnfm.2025.105431
Xiao Hu , Jianzhong Lin , Zhaosheng Yu , Zhaowu Lin , Jingyu Cui , Yan Xia
Equilibrium position and rotational behaviours of spheroid in an inertial rectangular microchannel flow of Oldroyd-B viscoelastic fluid is studied by the direct forcing/fictitious domain method. The results show that there are five kinds of equilibrium positions and four (three) kinds of rotational behaviours for the elasto-inertial migration of prolate (oblate) spheroids in an inertial rectangular channel flow. The spheroids gradually change to the corner (CO), channel centreline (CC), near corner (NCO), near channel centre (NCC) and bisector of the long wall (BLW) equilibrium positions as the elastic number decreases, the NCO and NCC equilibrium positions are newly found in the present works. When the fluid elasticity is large, only the large sphere displays the anomalous off-centreline NCC equilibrium position. With increasing the fluid inertia, the induced lateral migration velocity near the particle is enhanced, and the induced streamlines push all particles away from the CC equilibrium position. Spherical particles exhibit the highest induced velocity, then followed by the oblate spheroids, while prolate spheroids induce the lowest lateral migration velocity and consistently exhibit the closest distance to the channel centre. The particles are closer to the channel centre with decreasing the particle size, and with increasing the fluid elasticity. Those results are useful for designing a microfluidic chip with high separation efficiency.
{"title":"Equilibrium position and rotational behaviours of spheroid in an inertial rectangular microchannel flow of Oldroyd-B viscoelastic fluid","authors":"Xiao Hu , Jianzhong Lin , Zhaosheng Yu , Zhaowu Lin , Jingyu Cui , Yan Xia","doi":"10.1016/j.jnnfm.2025.105431","DOIUrl":"10.1016/j.jnnfm.2025.105431","url":null,"abstract":"<div><div>Equilibrium position and rotational behaviours of spheroid in an inertial rectangular microchannel flow of Oldroyd-B viscoelastic fluid is studied by the direct forcing/fictitious domain method. The results show that there are five kinds of equilibrium positions and four (three) kinds of rotational behaviours for the elasto-inertial migration of prolate (oblate) spheroids in an inertial rectangular channel flow. The spheroids gradually change to the corner (CO), channel centreline (CC), near corner (NCO), near channel centre (NCC) and bisector of the long wall (BLW) equilibrium positions as the elastic number decreases, the NCO and NCC equilibrium positions are newly found in the present works. When the fluid elasticity is large, only the large sphere displays the anomalous off-centreline NCC equilibrium position. With increasing the fluid inertia, the induced lateral migration velocity near the particle is enhanced, and the induced streamlines push all particles away from the CC equilibrium position. Spherical particles exhibit the highest induced velocity, then followed by the oblate spheroids, while prolate spheroids induce the lowest lateral migration velocity and consistently exhibit the closest distance to the channel centre. The particles are closer to the channel centre with decreasing the particle size, and with increasing the fluid elasticity. Those results are useful for designing a microfluidic chip with high separation efficiency.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"341 ","pages":"Article 105431"},"PeriodicalIF":2.7,"publicationDate":"2025-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143923750","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}
Pub Date : 2025-04-21DOI: 10.1016/j.jnnfm.2025.105420
A. Joulaei , H. Rahmani , S.M. Taghavi
We study the plane Poiseuille flow of viscoplastic fluids in channels with asymmetric superhydrophobic (SH) walls featuring transverse groove configurations in the thin channel limit. We use OpenFOAM simulations and the Papanastasiou regularization method to approximate the Bingham model. Focusing on variations in the upper SH wall’s characteristics, we explore the effects of slip number (), groove periodicity length (), slip area fraction (), and Bingham number () on flow dynamics, flow metrics and unyielded center plug morphology. We find that increasing , , and enhances slip velocity on the upper SH wall and reduces the normalized plug area () up to , while higher amplifies flow asymmetry, shifting and breaking center plugs. By introducing the concept of slippery equivalent systems, we demonstrate that varying groove configurations can yield identical effective slip lengths () with distinct plug morphologies, enabling precise control of viscoplastic fluid dynamics. We derive a simplified model to predict and , identifying a critical threshold at for regime transitions between unbroken (Regime I) and broken (Regime II) center plugs, leading to a six-dimensional manifold equation for classifying these regimes across parameter space.
{"title":"Control of viscoplastic fluid dynamics in superhydrophobic channels with asymmetric groove configurations","authors":"A. Joulaei , H. Rahmani , S.M. Taghavi","doi":"10.1016/j.jnnfm.2025.105420","DOIUrl":"10.1016/j.jnnfm.2025.105420","url":null,"abstract":"<div><div>We study the plane Poiseuille flow of viscoplastic fluids in channels with asymmetric superhydrophobic (SH) walls featuring transverse groove configurations in the thin channel limit. We use OpenFOAM simulations and the Papanastasiou regularization method to approximate the Bingham model. Focusing on variations in the upper SH wall’s characteristics, we explore the effects of slip number (<span><math><msub><mrow><mi>b</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>), groove periodicity length (<span><math><msub><mrow><mi>ℓ</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>), slip area fraction (<span><math><msub><mrow><mi>φ</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>), and Bingham number (<span><math><mi>B</mi></math></span>) on flow dynamics, flow metrics and unyielded center plug morphology. We find that increasing <span><math><msub><mrow><mi>b</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>, <span><math><msub><mrow><mi>φ</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>, and <span><math><msub><mrow><mi>ℓ</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> enhances slip velocity on the upper SH wall and reduces the normalized plug area (<span><math><mrow><mi>A</mi><mo>/</mo><msub><mrow><mi>A</mi></mrow><mrow><mn>0</mn></mrow></msub></mrow></math></span>) up to <span><math><mrow><msub><mrow><mi>φ</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>=</mo><mn>0</mn><mo>.</mo><mn>5</mn></mrow></math></span>, while higher <span><math><mi>B</mi></math></span> amplifies flow asymmetry, shifting and breaking center plugs. By introducing the concept of <em>slippery equivalent systems</em>, we demonstrate that varying groove configurations can yield identical effective slip lengths (<span><math><msub><mrow><mi>χ</mi></mrow><mrow><mi>T</mi></mrow></msub></math></span>) with distinct plug morphologies, enabling precise control of viscoplastic fluid dynamics. We derive a simplified model to predict <span><math><msub><mrow><mi>χ</mi></mrow><mrow><mi>T</mi></mrow></msub></math></span> and <span><math><mrow><mi>A</mi><mo>/</mo><msub><mrow><mi>A</mi></mrow><mrow><mn>0</mn></mrow></msub></mrow></math></span>, identifying a critical threshold at <span><math><mrow><mi>A</mi><mo>/</mo><msub><mrow><mi>A</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>≈</mo><mn>0</mn><mo>.</mo><mn>68</mn></mrow></math></span> for regime transitions between unbroken (Regime I) and broken (Regime II) center plugs, leading to a six-dimensional manifold equation for classifying these regimes across parameter space.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"341 ","pages":"Article 105420"},"PeriodicalIF":2.7,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143869095","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}
Pub Date : 2025-04-10DOI: 10.1016/j.jnnfm.2025.105417
Farshad Nazari , Andrei Potanin , Hadi Mohammadigoushki
In this study, we experimentally investigate the rheological and flow behavior of two-dimensional (2D) monodisperse aqueous foams, sheared between parallel plates using a custom-made rheo-optical apparatus with smooth and roughened walls. The foams were prepared using two commercially available detergents — Foam 1 and Foam 2 — while maintaining similar bubble sizes and liquid fractions. The linear viscoelastic results reveal that the Foam 1 consistently exhibits higher elastic and loss moduli than the Foam 2, regardless of boundary conditions, with roughened walls further enhancing these moduli in both foams. Additionally, the Foam 1 shows a lower viscoelastic relaxation frequency compared to the Foam 2, indicating a less mobile interface for the Foam 1. In the non-linear regime, significant differences were observed. Under smooth boundary conditions, Foam 2 exhibits yield stress behavior, whereas Foam 1 does not, despite having higher viscous stresses. The viscous stress in the Foam 1 scales with the capillary number as Ca, while for the Foam 2, the scaling depends on the boundary conditions: Ca for smooth walls and Ca for roughened walls. These variations in rheological behavior are attributed to differences in surfactant chemistry, leading to different interface mobilities, with the Foam 1 having a less mobile interface compared to the Foam 2.
{"title":"Flow of a two-dimensional liquid foam: Impact of surfactant type and boundary conditions","authors":"Farshad Nazari , Andrei Potanin , Hadi Mohammadigoushki","doi":"10.1016/j.jnnfm.2025.105417","DOIUrl":"10.1016/j.jnnfm.2025.105417","url":null,"abstract":"<div><div>In this study, we experimentally investigate the rheological and flow behavior of two-dimensional (2D) monodisperse aqueous foams, sheared between parallel plates using a custom-made rheo-optical apparatus with smooth and roughened walls. The foams were prepared using two commercially available detergents — Foam 1 and Foam 2 — while maintaining similar bubble sizes and liquid fractions. The linear viscoelastic results reveal that the Foam 1 consistently exhibits higher elastic and loss moduli than the Foam 2, regardless of boundary conditions, with roughened walls further enhancing these moduli in both foams. Additionally, the Foam 1 shows a lower viscoelastic relaxation frequency compared to the Foam 2, indicating a less mobile interface for the Foam 1. In the non-linear regime, significant differences were observed. Under smooth boundary conditions, Foam 2 exhibits yield stress behavior, whereas Foam 1 does not, despite having higher viscous stresses. The viscous stress in the Foam 1 scales with the capillary number as <span><math><mrow><msub><mrow><mi>τ</mi></mrow><mrow><mi>w</mi></mrow></msub><mo>∝</mo></mrow></math></span> Ca<span><math><msup><mrow></mrow><mrow><mn>0</mn><mo>.</mo><mn>5</mn></mrow></msup></math></span>, while for the Foam 2, the scaling depends on the boundary conditions: <span><math><mrow><msub><mrow><mi>τ</mi></mrow><mrow><mi>w</mi></mrow></msub><mo>∝</mo></mrow></math></span> Ca<span><math><msup><mrow></mrow><mrow><mn>0</mn><mo>.</mo><mn>85</mn></mrow></msup></math></span> for smooth walls and <span><math><mrow><msub><mrow><mi>τ</mi></mrow><mrow><mi>w</mi></mrow></msub><mo>∝</mo></mrow></math></span> Ca<span><math><msup><mrow></mrow><mrow><mn>0</mn><mo>.</mo><mn>65</mn></mrow></msup></math></span> for roughened walls. These variations in rheological behavior are attributed to differences in surfactant chemistry, leading to different interface mobilities, with the Foam 1 having a less mobile interface compared to the Foam 2.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"339 ","pages":"Article 105417"},"PeriodicalIF":2.7,"publicationDate":"2025-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143823802","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}
The understanding of rheological behavior of non-Brownian hard sphere suspensions is of importance from both the fundamental and applied perspectives. This is owing to their ubiquitous use in industry for many applications. However, most of the studies reported in literature pertain to non-colloidal hard sphere suspensions in a Newtonian matrix. In the present work, we report the rheological response of hollow glass microspheres (HGMs) suspended in a moderately entangled telechelic polymer of hydroxyl terminated polybutadiene (HTPB) across a wide concentration range i.e., volume fraction, ɸ varying from 0.07 to 0.6. Steady state and small amplitude oscillatory rheology (SAOR) measurements of the suspensions revealed a significant departure of the rheological response from that of non-Brownian hard sphere suspensions. The salient findings of the study are (a) pronounced shear thinning (b) increased storage and loss moduli with increased HGM content (c) low frequency storage moduli plateau across concentrations (d) percolation at ɸ =0.49–0.51 of HGM (e) significant difference in the high frequency dynamic modulus between HTPB and suspensions at ɸ > 0.5. Some of these rheological features resemble that of colloidal or Brownian suspensions and are suggestive of formation of network or gel-like structure. We invoke the role of HTPB-HGM interaction (FTIR spectroscopy), morphology of the suspensions (optical microscopy), plausible immobilization of telechelic chains on surface of HGM, entangled state of the telechelic as the mechanistic origins of the observed unusual rheological behavior of the studied suspensions. We posit that the present study is an important addition to experimental investigations in the field of hard sphere dispersions.
{"title":"Unusual rheological behavior of a moderately entangled telechelic polymer and hollow glass microsphere suspension via hydrogen bonding interactions","authors":"Praveen Sreenivasan , Srikanth Billa , Sangram Kesari Rath , Debdatta Ratna , Santanu Chattopadhyay","doi":"10.1016/j.jnnfm.2025.105419","DOIUrl":"10.1016/j.jnnfm.2025.105419","url":null,"abstract":"<div><div>The understanding of rheological behavior of non-Brownian hard sphere suspensions is of importance from both the fundamental and applied perspectives. This is owing to their ubiquitous use in industry for many applications. However, most of the studies reported in literature pertain to non-colloidal hard sphere suspensions in a Newtonian matrix. In the present work, we report the rheological response of hollow glass microspheres (HGMs) suspended in a moderately entangled telechelic polymer of hydroxyl terminated polybutadiene (HTPB) across a wide concentration range i.e., volume fraction, <em>ɸ</em> varying from 0.07 to 0.6. Steady state and small amplitude oscillatory rheology (SAOR) measurements of the suspensions revealed a significant departure of the rheological response from that of non-Brownian hard sphere suspensions. The salient findings of the study are (a) pronounced shear thinning (b) increased storage and loss moduli with increased HGM content (c) low frequency storage moduli plateau across concentrations (d) percolation at <em>ɸ =</em>0.49–0.51 of HGM (e) significant difference in the high frequency dynamic modulus between HTPB and suspensions at <em>ɸ ></em> 0.5. Some of these rheological features resemble that of colloidal or Brownian suspensions and are suggestive of formation of network or gel-like structure. We invoke the role of HTPB-HGM interaction (FTIR spectroscopy), morphology of the suspensions (optical microscopy), plausible immobilization of telechelic chains on surface of HGM, entangled state of the telechelic as the mechanistic origins of the observed unusual rheological behavior of the studied suspensions. We posit that the present study is an important addition to experimental investigations in the field of hard sphere dispersions.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"339 ","pages":"Article 105419"},"PeriodicalIF":2.7,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143843176","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}
Pub Date : 2025-04-01DOI: 10.1016/j.jnnfm.2025.105408
M.A. Carrozza , M. Hütter , L.G.B. Bremer , P.D. Anderson , M.A. Hulsen
A numerical implementation of two-phase flows of Newtonian fluids with a non-linear viscoelastic interface is validated and applied to the case of uniaxial extension of a drop in a matrix fluid. Second-order convergence in space and time is obtained with a Lagrangian-based interface tracking finite element method. The flow problem is analysed using dimensionless groups based on the relative magnitudes of the viscoelastic interfacial extra stress, the interfacial tension and the viscous stress of the bulk fluids. After fitting the intrinsic viscoelastic stress–strain behaviour of interfaces in shear to experimental results from the literature, the influence of interfacial rheology on the drop shape and interfacial stress is investigated. The drop shape is not significantly influenced by the viscoelastic properties of the interface if the interfacial viscoelastic stress, interfacial tension and bulk viscous stress are of the same order of magnitude. However, the interface develops distinct stress profiles for varying interfacial viscoelastic properties. For relatively large viscoelastic interface stress compared to interfacial tension and bulk viscous stress, simulations become unstable. Eventually, the interfacial viscoelastic stress exceeds the interfacial tension and bulk viscous stress, and possibly buckling of the interface occurs, caused by compressive stresses at the drop tip.
{"title":"Simulation of the extensional deformation of a drop with an elastoviscoplastic interface","authors":"M.A. Carrozza , M. Hütter , L.G.B. Bremer , P.D. Anderson , M.A. Hulsen","doi":"10.1016/j.jnnfm.2025.105408","DOIUrl":"10.1016/j.jnnfm.2025.105408","url":null,"abstract":"<div><div>A numerical implementation of two-phase flows of Newtonian fluids with a non-linear viscoelastic interface is validated and applied to the case of uniaxial extension of a drop in a matrix fluid. Second-order convergence in space and time is obtained with a Lagrangian-based interface tracking finite element method. The flow problem is analysed using dimensionless groups based on the relative magnitudes of the viscoelastic interfacial extra stress, the interfacial tension and the viscous stress of the bulk fluids. After fitting the intrinsic viscoelastic stress–strain behaviour of interfaces in shear to experimental results from the literature, the influence of interfacial rheology on the drop shape and interfacial stress is investigated. The drop shape is not significantly influenced by the viscoelastic properties of the interface if the interfacial viscoelastic stress, interfacial tension and bulk viscous stress are of the same order of magnitude. However, the interface develops distinct stress profiles for varying interfacial viscoelastic properties. For relatively large viscoelastic interface stress compared to interfacial tension and bulk viscous stress, simulations become unstable. Eventually, the interfacial viscoelastic stress exceeds the interfacial tension and bulk viscous stress, and possibly buckling of the interface occurs, caused by compressive stresses at the drop tip.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"339 ","pages":"Article 105408"},"PeriodicalIF":2.7,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143783703","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}
Pub Date : 2025-03-27DOI: 10.1016/j.jnnfm.2025.105418
Evgenios Gryparis , Alexandros Syrakos , Georgios C. Georgiou
The development of Bingham flow in concentric annular tubes in the presence of wall slip is investigated. It is assumed that slip occurs along both cylinders, following Navier's law, which states that the slip velocity is proportional to the wall shear stress. The open-source finite element software FEniCS is used for the numerical simulations along with the Papanastasiou regularization for the constitutive equation. To correctly determine the entrance region, various definitions of the development length are considered. In addition to the standard definition, which is based on the maximum velocity development, and the global development length, alternative definitions based on the development of the wall shear stresses and of the velocity at the two yield radii are considered. The combined effects of slip, yield stress and inertia on the different development lengths are systematically investigated. The yielded and unyielded zones are also determined using the von Mises criterion. The numerical results show that the standard development length fails to accurately capture the entrance region, even in the case of Newtonian flow with no-slip, and that the inner wall shear stress and yield lengths are also inadequate. The global and the outer wall shear stress and yield development lengths, which can be up to four times bigger than the standard development length, are more reliable. In agreement with previous studies, the development lengths are monotonically increasing with the Reynolds and Bingham numbers. As wall slip becomes stronger these reliable development lengths increase only initially reaching a maximum and then they are abruptly reduced to zero as the slip number approaches the critical value corresponding to sliding (unyielded) motion.
{"title":"Bingham flow development in annular tubes in the presence of wall slip","authors":"Evgenios Gryparis , Alexandros Syrakos , Georgios C. Georgiou","doi":"10.1016/j.jnnfm.2025.105418","DOIUrl":"10.1016/j.jnnfm.2025.105418","url":null,"abstract":"<div><div>The development of Bingham flow in concentric annular tubes in the presence of wall slip is investigated. It is assumed that slip occurs along both cylinders, following Navier's law, which states that the slip velocity is proportional to the wall shear stress. The open-source finite element software FEniCS is used for the numerical simulations along with the Papanastasiou regularization for the constitutive equation. To correctly determine the entrance region, various definitions of the development length are considered. In addition to the standard definition, which is based on the maximum velocity development, and the global development length, alternative definitions based on the development of the wall shear stresses and of the velocity at the two yield radii are considered. The combined effects of slip, yield stress and inertia on the different development lengths are systematically investigated. The yielded and unyielded zones are also determined using the von Mises criterion. The numerical results show that the standard development length fails to accurately capture the entrance region, even in the case of Newtonian flow with no-slip, and that the inner wall shear stress and yield lengths are also inadequate. The global and the outer wall shear stress and yield development lengths, which can be up to four times bigger than the standard development length, are more reliable. In agreement with previous studies, the development lengths are monotonically increasing with the Reynolds and Bingham numbers. As wall slip becomes stronger these reliable development lengths increase only initially reaching a maximum and then they are abruptly reduced to zero as the slip number approaches the critical value corresponding to sliding (unyielded) motion.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"339 ","pages":"Article 105418"},"PeriodicalIF":2.7,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143760470","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}
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