Pub Date : 2026-01-29DOI: 10.1016/j.jnnfm.2026.105560
C. Calvo , A. Tamburrino , C. Falcón
We present an experimental study of viscous effects in transient non-linear long wave propagation in two Newtonian fluids and one shear thinning fluid in the laminar flow regime. Using optical measuring techniques (Fourier Transform Profilometry), we show that the wave phase speed decreases in both glycerin and carboxymethylcellulose (CMC) solutions with respect to that in water. A decrease in wave phase speed is observed, and a dispersion relation is obtained for surface waves through dimensional analysis from five dimensionless groups: the dimensionless wave celerity, the shallowness parameter, dimensionless amplitude, Reynolds number and the flow index. To complete the picture on wave propagation, an empirical dependence between the wave attenuation and the last four dimensionless groups mentioned above is found for non-linear long surface waves in our working fluids. We conclude quantitatively about viscosity effects in non-linear long wave propagation.
{"title":"Experimental study of shear thinning effects on solitary wave propagation: A Newtonian fluid comparison","authors":"C. Calvo , A. Tamburrino , C. Falcón","doi":"10.1016/j.jnnfm.2026.105560","DOIUrl":"10.1016/j.jnnfm.2026.105560","url":null,"abstract":"<div><div>We present an experimental study of viscous effects in transient non-linear long wave propagation in two Newtonian fluids and one shear thinning fluid in the laminar flow regime. Using optical measuring techniques (Fourier Transform Profilometry), we show that the wave phase speed decreases in both glycerin and carboxymethylcellulose (CMC) solutions with respect to that in water. A decrease in wave phase speed is observed, and a dispersion relation is obtained for surface waves through dimensional analysis from five dimensionless groups: the dimensionless wave celerity, the shallowness parameter, dimensionless amplitude, Reynolds number and the flow index. To complete the picture on wave propagation, an empirical dependence between the wave attenuation and the last four dimensionless groups mentioned above is found for non-linear long surface waves in our working fluids. We conclude quantitatively about viscosity effects in non-linear long wave propagation.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"348 ","pages":"Article 105560"},"PeriodicalIF":2.8,"publicationDate":"2026-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146077775","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 : 2026-01-02DOI: 10.1016/j.jnnfm.2025.105559
Joseph V. Giliberto, Olivier Desjardins
Viscoelastic constitutive equations often model the elastic stress field through the use of an elastic dumbbell model that utilizes a conformation tensor to represent the average polymer configuration in the flow field. In a liquid–gas flow environment, the conformation tensor is a discontinuous quantity that only exists in the liquid phase. This discontinuity often presents numerical challenges that can be tackled through the use of very fine meshes at the interface to ensure the stress profile is accurately captured. In contrast, this work presents a hybrid advection scheme for the discontinuous conformation tensor field that uses a semi-Lagrangian geometric flux-based scheme in the direct vicinity of the liquid–gas interface and a MUSCL scheme in the bulk of the liquid, away from the interface. This hybrid method is found to be exactly conservative and bounded, and prevents any leakage of data across the liquid–gas interface. Verification and validation of this approach is done using the case of a gas bubble rising in a viscoelastic liquid. Results of the convergence study show that the hybrid scheme is able to converge to experimental results with 32 cells across the initial diameter of the bubble, which is one-third the resolution used in other computational studies comparing against experiments. The hybrid advection scheme is then applied to the case of a viscoelastic droplet deforming in homogeneous isotropic turbulence to investigate the influence of elastic stresses on droplet morphology. Results indicate that increasing viscoelastic stresses within the droplet significantly alters its deformation dynamics. At the moderate elastic stress levels tested, the droplet forms elongated liquid filaments delaying break-up for a longer duration. As viscoelasticity is further increased, deformation is progressively suppressed, ultimately stabilizing the droplet’s shape and preventing fragmentation.
{"title":"A sharp computational method for simulating multiphase viscoelastic flows","authors":"Joseph V. Giliberto, Olivier Desjardins","doi":"10.1016/j.jnnfm.2025.105559","DOIUrl":"10.1016/j.jnnfm.2025.105559","url":null,"abstract":"<div><div>Viscoelastic constitutive equations often model the elastic stress field through the use of an elastic dumbbell model that utilizes a conformation tensor to represent the average polymer configuration in the flow field. In a liquid–gas flow environment, the conformation tensor is a discontinuous quantity that only exists in the liquid phase. This discontinuity often presents numerical challenges that can be tackled through the use of very fine meshes at the interface to ensure the stress profile is accurately captured. In contrast, this work presents a hybrid advection scheme for the discontinuous conformation tensor field that uses a semi-Lagrangian geometric flux-based scheme in the direct vicinity of the liquid–gas interface and a MUSCL scheme in the bulk of the liquid, away from the interface. This hybrid method is found to be exactly conservative and bounded, and prevents any leakage of data across the liquid–gas interface. Verification and validation of this approach is done using the case of a gas bubble rising in a viscoelastic liquid. Results of the convergence study show that the hybrid scheme is able to converge to experimental results with 32 cells across the initial diameter of the bubble, which is one-third the resolution used in other computational studies comparing against experiments. The hybrid advection scheme is then applied to the case of a viscoelastic droplet deforming in homogeneous isotropic turbulence to investigate the influence of elastic stresses on droplet morphology. Results indicate that increasing viscoelastic stresses within the droplet significantly alters its deformation dynamics. At the moderate elastic stress levels tested, the droplet forms elongated liquid filaments delaying break-up for a longer duration. As viscoelasticity is further increased, deformation is progressively suppressed, ultimately stabilizing the droplet’s shape and preventing fragmentation.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"348 ","pages":"Article 105559"},"PeriodicalIF":2.8,"publicationDate":"2026-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145925955","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 : 2025-12-31DOI: 10.1016/j.jnnfm.2025.105558
Ayrton Cavallini Zotelle , Vinicius Gustavo Poletto , Felipe Barboza Pereira , Fernando Cesar De Lai , Renato do Nascimento Siqueira , Silvio Luiz de Mello Junqueira
This study employs a coupled Computational Fluid Dynamics–Discrete Element Method (CFD-DEM) to investigate the dynamic filtration behavior of non-Newtonian fluids in highly permeable porous media. The research explores the influence of rheological parameters, specifically the plasticity number () and power-law index (), over filter cake shape, filtered mass, and flow rate through the porous medium. Simulations consider Newtonian, shear-thinning, and viscoplastic fluids flowing through a porous matrix composed of a staggered array of cylindrical obstacles. The study also explores the impact of mesh resolution and regularization parameters on simulation stability. Results indicate that higher plasticity enhances sealing performance by avoiding settling and building evenly thickened particulate layers. Meanwhile, shear-thinning behavior increases local viscosity in low-shear zones, reducing the local flow rate and, therefore, mass retention. The combination of low and high yields the most effective filtration, minimizing fluid loss and retained mass. Findings highlight the critical role of fluid rheology in optimizing dynamic filtration and suggest that tailoring and can significantly improve the process.
{"title":"CFD-DEM simulation of dynamic filtration in heterogeneous porous media with viscoplastic and shear-thinning fluids","authors":"Ayrton Cavallini Zotelle , Vinicius Gustavo Poletto , Felipe Barboza Pereira , Fernando Cesar De Lai , Renato do Nascimento Siqueira , Silvio Luiz de Mello Junqueira","doi":"10.1016/j.jnnfm.2025.105558","DOIUrl":"10.1016/j.jnnfm.2025.105558","url":null,"abstract":"<div><div>This study employs a coupled Computational Fluid Dynamics–Discrete Element Method (CFD-DEM) to investigate the dynamic filtration behavior of non-Newtonian fluids in highly permeable porous media. The research explores the influence of rheological parameters, specifically the plasticity number (<span><math><mrow><mi>P</mi><mi>l</mi></mrow></math></span>) and power-law index (<span><math><mi>n</mi></math></span>), over filter cake shape, filtered mass, and flow rate through the porous medium. Simulations consider Newtonian, shear-thinning, and viscoplastic fluids flowing through a porous matrix composed of a staggered array of cylindrical obstacles. The study also explores the impact of mesh resolution and regularization parameters on simulation stability. Results indicate that higher plasticity enhances sealing performance by avoiding settling and building evenly thickened particulate layers. Meanwhile, shear-thinning behavior increases local viscosity in low-shear zones, reducing the local flow rate and, therefore, mass retention. The combination of low <span><math><mi>n</mi></math></span> and high <span><math><mrow><mi>P</mi><mi>l</mi></mrow></math></span> yields the most effective filtration, minimizing fluid loss and retained mass. Findings highlight the critical role of fluid rheology in optimizing dynamic filtration and suggest that tailoring <span><math><mrow><mi>P</mi><mi>l</mi></mrow></math></span> and <span><math><mi>n</mi></math></span> can significantly improve the process.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"348 ","pages":"Article 105558"},"PeriodicalIF":2.8,"publicationDate":"2025-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145925954","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 : 2025-12-31DOI: 10.1016/j.jnnfm.2025.105548
Pierre Saramito
In a few lines, the Oldroyd-B, FENE-P, Giesekus and FENE-CR models are shown as satisfying the second principle of thermodynamics. In addition, entropy estimates (a priori bounds) are easily obtained, together with explicit expressions for the dissipation. For the Giesekus and FENE-CR models, these estimates are new, while for the Oldroyd-B and FENE-P, there were already established. In all cases, they are obtained her e in a clear an concise manner, instead of long derivations. This approach could also be applied to the development of new constitutive equations, and some preliminary explorations are provided. The conformation tensor is identified in a purely kinematic context, in terms of the Cauchy–Green tensor. Consequently, the formulation in terms of the logarithm of conformation tensor is reinterpreted in terms of Hencky strain and its logarithmic corotational derivative. While useful for numerical computations, this also leads to much more concise and understandable formulations, but above all, it opens up new avenues for theoretical developments. This paper presents new developments of a work initiated by the author in a recent book (Springer, 2024), which is also reviewed here in a concise manner. We briefly recall how the standard generalized materials framework extends to large-strains kinematics in Eulerian frame.
{"title":"Yet another thermodynamic environment","authors":"Pierre Saramito","doi":"10.1016/j.jnnfm.2025.105548","DOIUrl":"10.1016/j.jnnfm.2025.105548","url":null,"abstract":"<div><div>In a few lines, the Oldroyd-B, FENE-P, Giesekus and FENE-CR models are shown as satisfying the second principle of thermodynamics. In addition, entropy estimates (<em>a priori</em> bounds) are easily obtained, together with explicit expressions for the dissipation. For the Giesekus and FENE-CR models, these estimates are new, while for the Oldroyd-B and FENE-P, there were already established. In all cases, they are obtained her e in a clear an concise manner, instead of long derivations. This approach could also be applied to the development of new constitutive equations, and some preliminary explorations are provided. The conformation tensor is identified in a purely kinematic context, in terms of the Cauchy–Green tensor. Consequently, the formulation in terms of the logarithm of conformation tensor is reinterpreted in terms of Hencky strain and its logarithmic corotational derivative. While useful for numerical computations, this also leads to much more concise and understandable formulations, but above all, it opens up new avenues for theoretical developments. This paper presents new developments of a work initiated by the author in a recent book (Springer, 2024), which is also reviewed here in a concise manner. We briefly recall how the standard generalized materials framework extends to large-strains kinematics in Eulerian frame.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"348 ","pages":"Article 105548"},"PeriodicalIF":2.8,"publicationDate":"2025-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145977791","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 : 2025-12-19DOI: 10.1016/j.jnnfm.2025.105544
Davide Amoroso, Massimiliano M. Villone
Understanding the role of elasticity in the stretching and relaxation processes of freestanding liquid films is a key step in the study of two-phase systems such as foams and emulsions. This work employs numerical simulations based on the finite element method to investigate the dynamics of viscoelastic films underoging biaxial extensional deformation followed by relaxation. Two constitutive equations (Oldroyd-B and Giesekus) are employed to capture the effects of elasticity, viscosity, and capillarity. A parametric study is performed to assess the effects of Weissenberg-number-variations on elastic energy accumulation and film thickness evolution. Distinct behaviors are found for the two rheological models: the relaxation of Oldroyd-B films is characterized by an increase in thickness at the center, referred to as ‘elastic leveling’; in contrast, Giesekus films exhibit a decrease in thickness that we define ‘elastic anti-leveling’. Our results highlight the critical role of viscoelastic effects in governing the transient behavior of freestanding films beyond classical capillary-driven flow.
{"title":"Numerical simulations of the stretching and relaxation dynamics of viscoelastic freestanding liquid films","authors":"Davide Amoroso, Massimiliano M. Villone","doi":"10.1016/j.jnnfm.2025.105544","DOIUrl":"10.1016/j.jnnfm.2025.105544","url":null,"abstract":"<div><div>Understanding the role of elasticity in the stretching and relaxation processes of freestanding liquid films is a key step in the study of two-phase systems such as foams and emulsions. This work employs numerical simulations based on the finite element method to investigate the dynamics of viscoelastic films underoging biaxial extensional deformation followed by relaxation. Two constitutive equations (Oldroyd-B and Giesekus) are employed to capture the effects of elasticity, viscosity, and capillarity. A parametric study is performed to assess the effects of Weissenberg-number-variations on elastic energy accumulation and film thickness evolution. Distinct behaviors are found for the two rheological models: the relaxation of Oldroyd-B films is characterized by an increase in thickness at the center, referred to as ‘elastic leveling’; in contrast, Giesekus films exhibit a decrease in thickness that we define ‘elastic anti-leveling’. Our results highlight the critical role of viscoelastic effects in governing the transient behavior of freestanding films beyond classical capillary-driven flow.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"348 ","pages":"Article 105544"},"PeriodicalIF":2.8,"publicationDate":"2025-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145841286","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 : 2025-12-13DOI: 10.1016/j.jnnfm.2025.105547
Chyan-Deng Jan, Le-Trang Nguyen
<div><div>Debris flows, which mobilize large volumes of water, sediment, and woody debris, pose significant risks to human communities and infrastructure. In wildfire-affected forested areas, the accumulation of woody debris in drainage channels is exacerbated, thereby increasing the potential for more hazardous debris flows. To examine the influence of woody debris on debris flow dynamics, an inclined channel test, allowing the observation of woody debris flow in an inclined channel and its deposition in a horizontal tank, was conducted with highly concentrated woody-debris suspensions composed of clay, silt, woody debris, and water. This study explores how variations in fine-sediment fraction (<span><math><msub><mi>C</mi><mrow><mi>v</mi><mi>f</mi></mrow></msub></math></span>), woody debris proportion (<span><math><msub><mi>C</mi><mrow><mi>v</mi><mi>g</mi></mrow></msub></math></span>), and woody debris size (<span><math><msub><mi>S</mi><mi>w</mi></msub></math></span>) impact flow behavior, including the entry speed (<span><math><msub><mi>V</mi><mn>0</mn></msub></math></span>) into the horizontal tank, and deposition characteristics such as runout distance (<span><math><msub><mi>L</mi><mi>R</mi></msub></math></span>), deposit width (<span><math><msub><mi>W</mi><mi>R</mi></msub></math></span>), deposit thickness (<span><math><msub><mi>H</mi><mi>R</mi></msub></math></span>), and final profiles on a <span><math><mrow><mn>2</mn><msup><mrow><mn>0</mn></mrow><mi>o</mi></msup></mrow></math></span> channel slope. To examine the influence of proportions and sizes of woody debris on the entry speed, an empirical equation is presented relating <span><math><msub><mi>V</mi><mn>0</mn></msub></math></span> to <span><math><msub><mi>C</mi><mrow><mi>v</mi><mi>f</mi></mrow></msub></math></span>, <span><math><msub><mi>C</mi><mrow><mi>v</mi><mi>g</mi></mrow></msub></math></span>, and <span><math><msub><mi>S</mi><mi>w</mi></msub></math></span> using multiple linear regression analysis. The results indicate that a higher <span><math><msub><mi>C</mi><mrow><mi>v</mi><mi>f</mi></mrow></msub></math></span> and <span><math><msub><mi>C</mi><mrow><mi>v</mi><mi>g</mi></mrow></msub></math></span> yields smaller entry speeds, leading to shorter runout distances, thicker deposits, and wider deposit extents. The tests of larger <span><math><msub><mi>S</mi><mi>w</mi></msub></math></span> generate larger entry speeds, resulting in longer runout distances while producing thinner and narrower deposits. Empirical equations relating <span><math><msub><mi>V</mi><mn>0</mn></msub></math></span> to <span><math><msub><mi>L</mi><mi>R</mi></msub></math></span> and <span><math><msub><mi>W</mi><mi>R</mi></msub></math></span> are also provided to further demonstrate the influence of entry speeds on the deposit characteristics. Additionally, a strong correlation was found between inclined channel test parameters (e.g., entry speed, runout distance, and maximum deposit width) and rheological parame
{"title":"Experimental investigation of movement and deposition of woody-debris suspensions in inclined channel tests","authors":"Chyan-Deng Jan, Le-Trang Nguyen","doi":"10.1016/j.jnnfm.2025.105547","DOIUrl":"10.1016/j.jnnfm.2025.105547","url":null,"abstract":"<div><div>Debris flows, which mobilize large volumes of water, sediment, and woody debris, pose significant risks to human communities and infrastructure. In wildfire-affected forested areas, the accumulation of woody debris in drainage channels is exacerbated, thereby increasing the potential for more hazardous debris flows. To examine the influence of woody debris on debris flow dynamics, an inclined channel test, allowing the observation of woody debris flow in an inclined channel and its deposition in a horizontal tank, was conducted with highly concentrated woody-debris suspensions composed of clay, silt, woody debris, and water. This study explores how variations in fine-sediment fraction (<span><math><msub><mi>C</mi><mrow><mi>v</mi><mi>f</mi></mrow></msub></math></span>), woody debris proportion (<span><math><msub><mi>C</mi><mrow><mi>v</mi><mi>g</mi></mrow></msub></math></span>), and woody debris size (<span><math><msub><mi>S</mi><mi>w</mi></msub></math></span>) impact flow behavior, including the entry speed (<span><math><msub><mi>V</mi><mn>0</mn></msub></math></span>) into the horizontal tank, and deposition characteristics such as runout distance (<span><math><msub><mi>L</mi><mi>R</mi></msub></math></span>), deposit width (<span><math><msub><mi>W</mi><mi>R</mi></msub></math></span>), deposit thickness (<span><math><msub><mi>H</mi><mi>R</mi></msub></math></span>), and final profiles on a <span><math><mrow><mn>2</mn><msup><mrow><mn>0</mn></mrow><mi>o</mi></msup></mrow></math></span> channel slope. To examine the influence of proportions and sizes of woody debris on the entry speed, an empirical equation is presented relating <span><math><msub><mi>V</mi><mn>0</mn></msub></math></span> to <span><math><msub><mi>C</mi><mrow><mi>v</mi><mi>f</mi></mrow></msub></math></span>, <span><math><msub><mi>C</mi><mrow><mi>v</mi><mi>g</mi></mrow></msub></math></span>, and <span><math><msub><mi>S</mi><mi>w</mi></msub></math></span> using multiple linear regression analysis. The results indicate that a higher <span><math><msub><mi>C</mi><mrow><mi>v</mi><mi>f</mi></mrow></msub></math></span> and <span><math><msub><mi>C</mi><mrow><mi>v</mi><mi>g</mi></mrow></msub></math></span> yields smaller entry speeds, leading to shorter runout distances, thicker deposits, and wider deposit extents. The tests of larger <span><math><msub><mi>S</mi><mi>w</mi></msub></math></span> generate larger entry speeds, resulting in longer runout distances while producing thinner and narrower deposits. Empirical equations relating <span><math><msub><mi>V</mi><mn>0</mn></msub></math></span> to <span><math><msub><mi>L</mi><mi>R</mi></msub></math></span> and <span><math><msub><mi>W</mi><mi>R</mi></msub></math></span> are also provided to further demonstrate the influence of entry speeds on the deposit characteristics. Additionally, a strong correlation was found between inclined channel test parameters (e.g., entry speed, runout distance, and maximum deposit width) and rheological parame","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"348 ","pages":"Article 105547"},"PeriodicalIF":2.8,"publicationDate":"2025-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145791262","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 : 2025-12-13DOI: 10.1016/j.jnnfm.2025.105546
Fatemeh Karami , Pavlos S. Stephanou
Since its introduction, the Giesekus model has received increased attention, particularly due to its ability to provide a non-vanishing second normal stress difference in simple shear. However, its derivation was based on a postulate regarding the linearity between the mobility tensor and the conformation tensor. In this work, we elaborate on the implications of this linearity and examine how its predictions are altered when the second-order and third-order corrections are considered. The predictions of the non-linear versions of the Giesekus model are found to be partially in better agreement with experimental and simulation data than those of the original Giesekus model in the case of uniaxial elongational flow.
{"title":"The Giesekus model revisited","authors":"Fatemeh Karami , Pavlos S. Stephanou","doi":"10.1016/j.jnnfm.2025.105546","DOIUrl":"10.1016/j.jnnfm.2025.105546","url":null,"abstract":"<div><div>Since its introduction, the Giesekus model has received increased attention, particularly due to its ability to provide a non-vanishing second normal stress difference in simple shear. However, its derivation was based on a postulate regarding the linearity between the mobility tensor and the conformation tensor. In this work, we elaborate on the implications of this linearity and examine how its predictions are altered when the second-order and third-order corrections are considered. The predictions of the non-linear versions of the Giesekus model are found to be partially in better agreement with experimental and simulation data than those of the original Giesekus model in the case of uniaxial elongational flow.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"348 ","pages":"Article 105546"},"PeriodicalIF":2.8,"publicationDate":"2025-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145791260","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}
In recent years, ion-selective membranes and membrane-based separation technologies have garnered significant attention due to their increasing integration in various industries, including energy storage and electrolyzer applications, which enable chemical extraction and/or separation via relevant phenomena such as electrodialysis, desalination, flow electrodes, capacitive deionization, and redox-flow battery systems. The interaction between the membrane surface and the electro-rheological (ER) properties of fluid modulates the inherent ion transport dynamics. The induced electric current subsequently alters the flow field, thereby either enhancing or inhibiting the overall separation efficiency, depending on the applied electric field strength. Additionally, given the non-uniform ionic concentration distribution near the membrane surface, electro-convective currents ultimately lead to a net over-limiting current, followed by a relative suppression of advective ion transport. Such irregular loading and unloading cycles may lead to excessive ion accumulation on electrode surfaces, accelerating dendrite formation, which in turn degrades electrode performance and compromises membrane integrity. Therefore, the present study investigates the role of shear-thinning electrolytes in mitigating electroconvection near ion-selective membranes. A computational model is employed to solve the coupled Poisson-Nernst–Planck equation and the momentum equations, which leads to the evolution of ion distribution profiles and electrokinetic flow instabilities. The extensive numerical simulations yielded the flow attributes in terms of instantaneous velocity, concentration contours, streamlines, ionic current density, and average kinetic energy. In contrast, prolonged chaotic convection facilitates a more uniform distribution of ions within the electrolyte. The enhanced shear thinning effect sharpens both velocity and ionic concentration gradients adjacent to the membrane surface, thereby increasing ionic flux. In general, shear-thinning electrolytes present a promising strategy for mitigating dendrite formation, ultimately improving the operational stability and longevity of electrochemical devices.
{"title":"Influence of shear-thinning rheology on electroconvection around ion-selective membrane","authors":"Saurabh Maurya , Mohit Trivedi , Neelkanth Nirmalkar","doi":"10.1016/j.jnnfm.2025.105545","DOIUrl":"10.1016/j.jnnfm.2025.105545","url":null,"abstract":"<div><div>In recent years, ion-selective membranes and membrane-based separation technologies have garnered significant attention due to their increasing integration in various industries, including energy storage and electrolyzer applications, which enable chemical extraction and/or separation via relevant phenomena such as electrodialysis, desalination, flow electrodes, capacitive deionization, and redox-flow battery systems. The interaction between the membrane surface and the electro-rheological (ER) properties of fluid modulates the inherent ion transport dynamics. The induced electric current subsequently alters the flow field, thereby either enhancing or inhibiting the overall separation efficiency, depending on the applied electric field strength. Additionally, given the non-uniform ionic concentration distribution near the membrane surface, electro-convective currents ultimately lead to a net over-limiting current, followed by a relative suppression of advective ion transport. Such irregular loading and unloading cycles may lead to excessive ion accumulation on electrode surfaces, accelerating dendrite formation, which in turn degrades electrode performance and compromises membrane integrity. Therefore, the present study investigates the role of shear-thinning electrolytes in mitigating electroconvection near ion-selective membranes. A computational model is employed to solve the coupled Poisson-Nernst–Planck equation and the momentum equations, which leads to the evolution of ion distribution profiles and electrokinetic flow instabilities. The extensive numerical simulations yielded the flow attributes in terms of instantaneous velocity, concentration contours, streamlines, ionic current density, and average kinetic energy. In contrast, prolonged chaotic convection facilitates a more uniform distribution of ions within the electrolyte. The enhanced shear thinning effect sharpens both velocity and ionic concentration gradients adjacent to the membrane surface, thereby increasing ionic flux. In general, shear-thinning electrolytes present a promising strategy for mitigating dendrite formation, ultimately improving the operational stability and longevity of electrochemical devices.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"348 ","pages":"Article 105545"},"PeriodicalIF":2.8,"publicationDate":"2025-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145791259","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 : 2025-12-04DOI: 10.1016/j.jnnfm.2025.105534
Rishi Kumar , K. Muralidhar , Indranil Saha Dalal
This study investigates the effects of geometric model reduction on blood flow simulations in the patient-specific descending aorta, followed by speed-accuracy trade-off analysis using 3D simulations. We demonstrate how wall shear stresses (WSS) can be reliably estimated for such realistic arteries using significantly faster simulations of highly idealized equivalent geometries, for any blood rheology model. CFD simulations (3D) are performed at two levels of geometry reduction employing realistic pulsatile inflow and pressure outlet boundary conditions and utilizing both Newtonian and non-Newtonian blood rheology models, including the one developed recently by Apostolidis and Beris. The first level of reduction does not retain effects due to local asymmetry but can approximate various flow parameters and patterns, while showing a significant computational speedup. However, further simplification to an idealized smooth geometry loses all information about the vortex structures and flow circulation. The non-Newtonian models retain more accuracy than the Newtonian models in geometry reductions, as quantified by correlations defined in this study. The idealized smooth geometry, combined with area correction, yields WSS estimates that closely approximate those of the actual artery. This study is expected to be applicable in geometric reductions (and speed enhancements) for more complex patient-specific 3D simulations while maintaining accuracy.
{"title":"Effects of geometric modeling and blood rheology in patient-specific arterial blood flow simulations with speed-accuracy trade-off analysis","authors":"Rishi Kumar , K. Muralidhar , Indranil Saha Dalal","doi":"10.1016/j.jnnfm.2025.105534","DOIUrl":"10.1016/j.jnnfm.2025.105534","url":null,"abstract":"<div><div>This study investigates the effects of geometric model reduction on blood flow simulations in the patient-specific descending aorta, followed by speed-accuracy trade-off analysis using 3D simulations. We demonstrate how wall shear stresses (WSS) can be reliably estimated for such realistic arteries using significantly faster simulations of highly idealized equivalent geometries, for any blood rheology model. CFD simulations (3D) are performed at two levels of geometry reduction employing realistic pulsatile inflow and pressure outlet boundary conditions and utilizing both Newtonian and non-Newtonian blood rheology models, including the one developed recently by Apostolidis and Beris. The first level of reduction does not retain effects due to local asymmetry but can approximate various flow parameters and patterns, while showing a significant computational speedup. However, further simplification to an idealized smooth geometry loses all information about the vortex structures and flow circulation. The non-Newtonian models retain more accuracy than the Newtonian models in geometry reductions, as quantified by correlations defined in this study. The idealized smooth geometry, combined with area correction, yields WSS estimates that closely approximate those of the actual artery. This study is expected to be applicable in geometric reductions (and speed enhancements) for more complex patient-specific 3D simulations while maintaining accuracy.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"348 ","pages":"Article 105534"},"PeriodicalIF":2.8,"publicationDate":"2025-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145665694","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 : 2025-11-21DOI: 10.1016/j.jnnfm.2025.105533
Soham Jariwala , Norman J. Wagner, Antony N. Beris
Aggregating suspensions can be found in many materials, such as food products, biological fluids, printer inks, paints, and slurries. These suspensions display unique viscoelastic and thixotropic behavior due to the way the agglomerates formed by interparticle attraction undergo elastic deformation, aggregation, and breakage. In this work we show how it is possible to describe inhomogeneities induced by stress-induced migration by using a population balance-based constitutive model [Mwasame et al. AIChE J. 63 (2017) 517-531]. An important advantage of this model over phenomenological constitutive models, such as structure kinetics models, is that it can describe both the kinetics of aggregation and breakage as well as the migration fluxes in terms of the local microscopic structural descriptors, such as the volume fraction of primary particles, the fractal dimension, and the moments of the agglomerate size distribution.
In the present work, we adapt this mesoscale structural description to resolve the flow-induced migration behavior exhibited in pipe flows by coupling with a modified diffusive flux model proposed by Phillips et al. [Phys. Fluids 4 (1992) 30-40]. Our study focuses on fully-developed, pressure-driven (Poiseuille) flows in a tube, both steady and transient. We use numerical simulations based on Chebyshev orthogonal polynomial approximations of the variables along the radial directions within an efficient Galerkin weighted residuals methodology. The development of concentration inhomogeneities is investigated along with their effects on the stress that arises from thixotropy and viscoelasticity in both steady state and transient flows. Additionally, we use wall slip to appropriately model the particle-free layer than forms near the tube wall. Of potential significance to applications is the observation that the superposition of an oscillatory pressure gradient to a steady one can lead to a reduction in the power dissipation for a given average flow rate.
{"title":"Flow-induced migration of aggregating suspensions in pipe flow","authors":"Soham Jariwala , Norman J. Wagner, Antony N. Beris","doi":"10.1016/j.jnnfm.2025.105533","DOIUrl":"10.1016/j.jnnfm.2025.105533","url":null,"abstract":"<div><div>Aggregating suspensions can be found in many materials, such as food products, biological fluids, printer inks, paints, and slurries. These suspensions display unique viscoelastic and thixotropic behavior due to the way the agglomerates formed by interparticle attraction undergo elastic deformation, aggregation, and breakage. In this work we show how it is possible to describe inhomogeneities induced by stress-induced migration by using a population balance-based constitutive model [Mwasame et al. AIChE J. 63 (2017) 517-531]. An important advantage of this model over phenomenological constitutive models, such as structure kinetics models, is that it can describe both the kinetics of aggregation and breakage as well as the migration fluxes in terms of the local microscopic structural descriptors, such as the volume fraction of primary particles, the fractal dimension, and the moments of the agglomerate size distribution.</div><div>In the present work, we adapt this mesoscale structural description to resolve the flow-induced migration behavior exhibited in pipe flows by coupling with a modified diffusive flux model proposed by Phillips et al. [Phys. Fluids 4 (1992) 30-40]. Our study focuses on fully-developed, pressure-driven (Poiseuille) flows in a tube, both steady and transient. We use numerical simulations based on Chebyshev orthogonal polynomial approximations of the variables along the radial directions within an efficient Galerkin weighted residuals methodology. The development of concentration inhomogeneities is investigated along with their effects on the stress that arises from thixotropy and viscoelasticity in both steady state and transient flows. Additionally, we use wall slip to appropriately model the particle-free layer than forms near the tube wall. Of potential significance to applications is the observation that the superposition of an oscillatory pressure gradient to a steady one can lead to a reduction in the power dissipation for a given average flow rate.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"348 ","pages":"Article 105533"},"PeriodicalIF":2.8,"publicationDate":"2025-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145791261","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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