Pub Date : 2025-10-20DOI: 10.1016/j.jnnfm.2025.105513
Shuen He , Qiang Li , Hao Zhou , Meng-Ge Li , Yubai Li , Yong He , Wei-Tao Wu , Yue Hua
Bubble retention caused by the high viscosity of gelled propellants poses a significant challenge to combustion stability and performance in propulsion systems. To address this, the present study investigates the dynamic behavior of a single bubble in shear-thinning gelled propellants flowing through corrugated channels. Numerical simulations are conducted employing the Volume of Fluid (VOF) approach, with a modified Carreau–Yasuda model applied to represent the non-Newtonian viscosity characteristics. The effects of channel geometry, temperature, and inlet velocity on bubble dynamics and apparent viscosity are analyzed. The results indicate that bubble velocity is highest in trapezoidal channels, followed by sinusoidal and smooth channels. Increasing the corrugation amplitude enhances bubble speed, while higher temperatures reduce it. At low inlet velocities, the bubble maintains its shape; at moderate velocities, it deforms and recovers; and at high velocities, it splits. These findings provide valuable insights into bubble behavior in gelled propellants and contribute to the optimization of propulsion system design.
{"title":"Single bubble dynamics in temperature-sensitive gelled propellants flowing through corrugated channels","authors":"Shuen He , Qiang Li , Hao Zhou , Meng-Ge Li , Yubai Li , Yong He , Wei-Tao Wu , Yue Hua","doi":"10.1016/j.jnnfm.2025.105513","DOIUrl":"10.1016/j.jnnfm.2025.105513","url":null,"abstract":"<div><div>Bubble retention caused by the high viscosity of gelled propellants poses a significant challenge to combustion stability and performance in propulsion systems. To address this, the present study investigates the dynamic behavior of a single bubble in shear-thinning gelled propellants flowing through corrugated channels. Numerical simulations are conducted employing the Volume of Fluid (VOF) approach, with a modified Carreau–Yasuda model applied to represent the non-Newtonian viscosity characteristics. The effects of channel geometry, temperature, and inlet velocity on bubble dynamics and apparent viscosity are analyzed. The results indicate that bubble velocity is highest in trapezoidal channels, followed by sinusoidal and smooth channels. Increasing the corrugation amplitude enhances bubble speed, while higher temperatures reduce it. At low inlet velocities, the bubble maintains its shape; at moderate velocities, it deforms and recovers; and at high velocities, it splits. These findings provide valuable insights into bubble behavior in gelled propellants and contribute to the optimization of propulsion system design.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"347 ","pages":"Article 105513"},"PeriodicalIF":2.8,"publicationDate":"2025-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145419947","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 : 2025-10-18DOI: 10.1016/j.jnnfm.2025.105512
Martin Lardy , Sham Tlili , Simon Gsell
Fluid-like materials are ubiquitous, spanning from living biological tissues to geological formations, and across scales ranging from micrometers to kilometers. Inferring their rheological properties remains a major challenge, particularly when traditional rheometry fails to capture their complex, three-dimensional, and often heterogeneous behavior. This difficulty is exacerbated by system size, boundary conditions, and other material-specific physical, chemical, or thermal constraints. In this work, we explore whether rheological laws can be inferred directly from flow observations. We propose a physics-informed neural network (PINN) framework designed to learn constitutive viscoplastic laws from velocity field data alone. Our method uses a neural network to interpolate the velocity field, enabling the computation of velocity gradients via automatic differentiation. These gradients are used to estimate the residuals of the governing conservation laws, which implicitly depend on the unknown rheology. We jointly optimize both the constitutive model and the velocity field representation by minimizing the physical residuals and discrepancies from observed data. We validate our approach on synthetic velocity fields generated from numerical simulations using Herschel–Bulkley, Carreau and Papanastasiou models under various flow conditions. The algorithm reliably infers rheological parameters, even in the presence of significant noise. We analyze the dependence of inference performance on flow geometry and sampling, highlighting the importance of shear rate distribution in the dataset. Finally, we explore preliminary strategies for model-agnostic inference via embedded model selection, demonstrating the potential of PINNs for identifying the most suitable rheological law from candidate models. This study illustrates how machine learning, and PINNs in particular, can enhance our ability to probe the rheology of complex fluids using velocity field data alone—paving the way for new approaches in computational rheology and material characterization.
{"title":"Inferring viscoplastic models from velocity fields: A physics-informed neural network approach","authors":"Martin Lardy , Sham Tlili , Simon Gsell","doi":"10.1016/j.jnnfm.2025.105512","DOIUrl":"10.1016/j.jnnfm.2025.105512","url":null,"abstract":"<div><div>Fluid-like materials are ubiquitous, spanning from living biological tissues to geological formations, and across scales ranging from micrometers to kilometers. Inferring their rheological properties remains a major challenge, particularly when traditional rheometry fails to capture their complex, three-dimensional, and often heterogeneous behavior. This difficulty is exacerbated by system size, boundary conditions, and other material-specific physical, chemical, or thermal constraints. In this work, we explore whether rheological laws can be inferred directly from flow observations. We propose a physics-informed neural network (PINN) framework designed to learn constitutive viscoplastic laws from velocity field data alone. Our method uses a neural network to interpolate the velocity field, enabling the computation of velocity gradients via automatic differentiation. These gradients are used to estimate the residuals of the governing conservation laws, which implicitly depend on the unknown rheology. We jointly optimize both the constitutive model and the velocity field representation by minimizing the physical residuals and discrepancies from observed data. We validate our approach on synthetic velocity fields generated from numerical simulations using Herschel–Bulkley, Carreau and Papanastasiou models under various flow conditions. The algorithm reliably infers rheological parameters, even in the presence of significant noise. We analyze the dependence of inference performance on flow geometry and sampling, highlighting the importance of shear rate distribution in the dataset. Finally, we explore preliminary strategies for model-agnostic inference via embedded model selection, demonstrating the potential of PINNs for identifying the most suitable rheological law from candidate models. This study illustrates how machine learning, and PINNs in particular, can enhance our ability to probe the rheology of complex fluids using velocity field data alone—paving the way for new approaches in computational rheology and material characterization.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"346 ","pages":"Article 105512"},"PeriodicalIF":2.8,"publicationDate":"2025-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145363533","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 : 2025-10-15DOI: 10.1016/j.jnnfm.2025.105511
Abbas Sheikh
This study investigates the time-dependent performance of the FENE-P and Rouse models as representative coarse-grained elastic chains. The analysis is conducted within two conventional rheometric shear flows: drag Couette flow, considered during both the “inception” and “start-up” phases, and pressure-driven Poiseuille flow. The primary objective of this research is to examine the rheological behavior with respect to the growth of shear stress, first normal stress difference, velocity development, and structural evolution, which includes the mean-square end-to-end distance, radius of gyration, and orientation functions of the elastic chains. To implement these molecular models, a CONNFFESSIT-like methodology was employed. Initially, the procedure was validated through a thorough comparison of the results with existing data, and subsequently applied under diverse conditions, including varying shear rates, chain segment numbers, and degrees of chain extensibility. The study revealed a fundamental distinction in the rheological behavior of the FENE-P chain, which has limited extensibility under flow, and the Rouse chain, which can extend indefinitely. Although start-up flow in a circular tube may appear straightforward, the application of these models through the micro–macro framework makes it possible to obtain new results, thereby demonstrating the versatility of the methodology.
{"title":"Transitional shear flow of elastic chains: A theoretical study based on molecular rheology","authors":"Abbas Sheikh","doi":"10.1016/j.jnnfm.2025.105511","DOIUrl":"10.1016/j.jnnfm.2025.105511","url":null,"abstract":"<div><div>This study investigates the time-dependent performance of the FENE-P and Rouse models as representative coarse-grained elastic chains. The analysis is conducted within two conventional rheometric shear flows: drag Couette flow, considered during both the “inception” and “start-up” phases, and pressure-driven Poiseuille flow. The primary objective of this research is to examine the rheological behavior with respect to the growth of shear stress, first normal stress difference, velocity development, and structural evolution, which includes the mean-square end-to-end distance, radius of gyration, and orientation functions of the elastic chains. To implement these molecular models, a CONNFFESSIT-like methodology was employed. Initially, the procedure was validated through a thorough comparison of the results with existing data, and subsequently applied under diverse conditions, including varying shear rates, chain segment numbers, and degrees of chain extensibility. The study revealed a fundamental distinction in the rheological behavior of the FENE-P chain, which has limited extensibility under flow, and the Rouse chain, which can extend indefinitely. Although start-up flow in a circular tube may appear straightforward, the application of these models through the micro–macro framework makes it possible to obtain new results, thereby demonstrating the versatility of the methodology.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"347 ","pages":"Article 105511"},"PeriodicalIF":2.8,"publicationDate":"2025-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145366212","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 : 2025-10-14DOI: 10.1016/j.jnnfm.2025.105510
Belaid Hadj Arab , Zineeddine Louna , Mohamed Mahfoud , Paulo R de Souza Mendes , Yamid J. Garcia-Blanco , Admilson T Franco
This paper presents an experimental study of yield stress fluid flow in a rectangular channel containing an abrupt contraction with an aspect ratio of 4:1. The flow dynamics analysis is based on Laser Doppler Velocimetry (LDV), which enables the local characterization of velocities. The longitudinal and transversal velocity components are measured upstream, at, and downstream of the contraction to assess the effect of this geometric change and inertia on the flow. Profiles of the longitudinal velocity component, u, highlight the existence of a dead zone at the corners of the contraction, where a slip line is identified and located at the same position as the contraction. The establishment length of the downstream flow is also determined, and a linear correlation is proposed. A plug zone, characterized by a constant velocity at the center of the channel, is observed for different flow rates and position conditions. The transversal velocity component, v, remains nearly zero throughout the domain, except in the contraction region, where elongation effects become significant. Analysis of velocity distribution along the central axis reveals velocity peaks immediately downstream of the contraction, particularly at low flow rates. The elongation rate reaches a maximum at the contraction, and a linear correlation is established between this maximum value and the flow rate. A correlation describing the slip velocity at the wall is also proposed. Finally, the study is completed by establishing correlations between the friction factor, f, the Euler number, and the Reynolds number, which are evaluated at the upstream and downstream regions of the contraction.
{"title":"Experimental investigation of yield stress fluid flow in an abrupt 4:1 planar contraction using laser Doppler velocimetry: Effects of inertia and geometry","authors":"Belaid Hadj Arab , Zineeddine Louna , Mohamed Mahfoud , Paulo R de Souza Mendes , Yamid J. Garcia-Blanco , Admilson T Franco","doi":"10.1016/j.jnnfm.2025.105510","DOIUrl":"10.1016/j.jnnfm.2025.105510","url":null,"abstract":"<div><div>This paper presents an experimental study of yield stress fluid flow in a rectangular channel containing an abrupt contraction with an aspect ratio of 4:1. The flow dynamics analysis is based on Laser Doppler Velocimetry (LDV), which enables the local characterization of velocities. The longitudinal and transversal velocity components are measured upstream, at, and downstream of the contraction to assess the effect of this geometric change and inertia on the flow. Profiles of the longitudinal velocity component, <em>u,</em> highlight the existence of a dead zone at the corners of the contraction, where a slip line is identified and located at the same position as the contraction. The establishment length of the downstream flow is also determined, and a linear correlation is proposed. A plug zone, characterized by a constant velocity at the center of the channel, is observed for different flow rates and position conditions. The transversal velocity component, <em>v</em>, remains nearly zero throughout the domain, except in the contraction region, where elongation effects become significant. Analysis of velocity distribution along the central axis reveals velocity peaks immediately downstream of the contraction, particularly at low flow rates. The elongation rate reaches a maximum at the contraction, and a linear correlation is established between this maximum value and the flow rate. A correlation describing the slip velocity at the wall is also proposed. Finally, the study is completed by establishing correlations between the friction factor, <em>f,</em> the Euler number, and the Reynolds number, which are evaluated at the upstream and downstream regions of the contraction.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"346 ","pages":"Article 105510"},"PeriodicalIF":2.8,"publicationDate":"2025-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145363612","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}
Understanding the influence of inter-stenosis length (or spacing) on hemodynamics in dually stenosed blood vessels is critical for advancing our knowledge of cardiovascular diseases and their treatment. This study employs a two-phase Eulerian-granular model, incorporating kinetic theory to capture red blood cell (RBC) particle mechanics, to investigate hemodynamics in a dual-stenosed arterial vessel with a 75% degree of stenosis (DOS). To validate our approach, we benchmarked it against in vitro experimental velocity profiles reported by Yeleswarapu et al. (1998). With a maximum deviation of 7.24%, the current model shows improved agreement compared to other tested approaches, including both single-phase (Newtonian) and two-phase (Euler–Euler two-fluid) models. Our findings reveal that shorter inter-stenotic spacings lead to elevated velocity gradients, intensifying local inertial effects. Conversely, a longer spacing allows the flow more distance to recover and re-laminarize, stabilizing the velocity profile. The presence of stenosis significantly disrupts the typical central RBC core surrounded by plasma. Specifically, at short inter-stenotic lengths, the disturbed flow from the first stenosis lacks sufficient distance to re-establish shear gradient-driven RBC migration. This inhibits the formation of a well-defined core hematocrit, resulting in a more dispersed or skewed RBC distribution. Furthermore, short inter-stenotic lengths promote stronger flow interaction and the generation of persistent helical vortices in the downstream region. A greater inter-stenotic length facilitates partial re-laminarization and vortex dissipation, leading to a reduction in downstream helicity and a transition toward more organized flow. Area-averaged wall shear stress (AWSS) increases with decreasing inter-stenotic length, particularly at the stenosis throat. Notably, this study also demonstrates that the single-phase Newtonian model over predicts flow separation and recirculation compared to our two-phase approach. Overall, this study highlights the capabilities of the two-phase Euler–granular model in accurately simulating complex blood flow dynamics within stenosed arteries, offering potential extensions for investigating the hemodynamics of other complex biological systems.
{"title":"Investigating hemodynamic effects of consecutive arterial stenoses using an Eulerian granular two-phase model","authors":"Siddhartha Sankar Das, Dasari Abhiram, Swarup Kumar Mahapatra","doi":"10.1016/j.jnnfm.2025.105508","DOIUrl":"10.1016/j.jnnfm.2025.105508","url":null,"abstract":"<div><div>Understanding the influence of inter-stenosis length (or spacing) on hemodynamics in dually stenosed blood vessels is critical for advancing our knowledge of cardiovascular diseases and their treatment. This study employs a two-phase Eulerian-granular model, incorporating kinetic theory to capture red blood cell (RBC) particle mechanics, to investigate hemodynamics in a dual-stenosed arterial vessel with a 75% degree of stenosis (DOS). To validate our approach, we benchmarked it against in vitro experimental velocity profiles reported by Yeleswarapu et al. (1998). With a maximum deviation of 7.24%, the current model shows improved agreement compared to other tested approaches, including both single-phase (Newtonian) and two-phase (Euler–Euler two-fluid) models. Our findings reveal that shorter inter-stenotic spacings lead to elevated velocity gradients, intensifying local inertial effects. Conversely, a longer spacing allows the flow more distance to recover and re-laminarize, stabilizing the velocity profile. The presence of stenosis significantly disrupts the typical central RBC core surrounded by plasma. Specifically, at short inter-stenotic lengths, the disturbed flow from the first stenosis lacks sufficient distance to re-establish shear gradient-driven RBC migration. This inhibits the formation of a well-defined core hematocrit, resulting in a more dispersed or skewed RBC distribution. Furthermore, short inter-stenotic lengths promote stronger flow interaction and the generation of persistent helical vortices in the downstream region. A greater inter-stenotic length facilitates partial re-laminarization and vortex dissipation, leading to a reduction in downstream helicity and a transition toward more organized flow. Area-averaged wall shear stress (AWSS) increases with decreasing inter-stenotic length, particularly at the stenosis throat. Notably, this study also demonstrates that the single-phase Newtonian model over predicts flow separation and recirculation compared to our two-phase approach. Overall, this study highlights the capabilities of the two-phase Euler–granular model in accurately simulating complex blood flow dynamics within stenosed arteries, offering potential extensions for investigating the hemodynamics of other complex biological systems.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"346 ","pages":"Article 105508"},"PeriodicalIF":2.8,"publicationDate":"2025-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145321353","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 : 2025-10-10DOI: 10.1016/j.jnnfm.2025.105509
Hadis Torabi , Hadis Zarrin , Ehsan Behzadfar
Rheological analysis of biodegradable polymers is often complicated by structural mutations and thermal degradation during testing, leading to inaccurate data and unreliable modeling. These effects are particularly pronounced in conventional small-amplitude oscillatory shear (SAOS) experiments, which require extended exposure to elevated temperatures. In this study, an alternative approach is introduced based on time-resolved rheometry (TRR) to minimize the impact of degradation and isolate intrinsic rheological behavior. By capturing data across different timescales, this method decouples degradation kinetics from rheological responses, enabling the construction of more accurate flow curves and material functions. The effectiveness of this approach was validated by comparing it to conventional SAOS protocols across several polyhydroxyalkanoates. Our results show that TRR-based measurements yield more reliable predictions of viscoelastic properties, including relaxation moduli and startup shear viscosities. The improved data quality leads to superior fits in constitutive equation modeling. This methodology offers a more efficient and degradation-resistant strategy for rheological testing, with significant implications for optimizing the processing and performance of biodegradable polymers.
{"title":"Mitigating degradation-induced artifacts in rheological modeling of biopolymers using time-resolved rheology","authors":"Hadis Torabi , Hadis Zarrin , Ehsan Behzadfar","doi":"10.1016/j.jnnfm.2025.105509","DOIUrl":"10.1016/j.jnnfm.2025.105509","url":null,"abstract":"<div><div>Rheological analysis of biodegradable polymers is often complicated by structural mutations and thermal degradation during testing, leading to inaccurate data and unreliable modeling. These effects are particularly pronounced in conventional small-amplitude oscillatory shear (SAOS) experiments, which require extended exposure to elevated temperatures. In this study, an alternative approach is introduced based on time-resolved rheometry (TRR) to minimize the impact of degradation and isolate intrinsic rheological behavior. By capturing data across different timescales, this method decouples degradation kinetics from rheological responses, enabling the construction of more accurate flow curves and material functions. The effectiveness of this approach was validated by comparing it to conventional SAOS protocols across several polyhydroxyalkanoates. Our results show that TRR-based measurements yield more reliable predictions of viscoelastic properties, including relaxation moduli and startup shear viscosities. The improved data quality leads to superior fits in constitutive equation modeling. This methodology offers a more efficient and degradation-resistant strategy for rheological testing, with significant implications for optimizing the processing and performance of biodegradable polymers.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"346 ","pages":"Article 105509"},"PeriodicalIF":2.8,"publicationDate":"2025-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145321354","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 : 2025-09-27DOI: 10.1016/j.jnnfm.2025.105498
P.T. Griffiths , D. Xu , L. Davoust
This study presents a theoretical and numerical investigation of interfacial flows of oxidised liquid metals in a shallow annular channel in the absence of inertial effects. For the first time, viscoplastic surface behaviour induced by oxidation is modelled using a bi-viscosity law within a framework that also accounts for interfacial curvature governed by the Young–Laplace equation. By solving a coupled bulk-surface flow system, the effects of surface rheology, contact angle, and dimensionless capillary length on surface velocity and surface shear rate profiles are quantified. Results highlight the competing influences of hydrophobicity and viscoplasticity on surface and bulk flow characteristics and demonstrate that accurate modelling of such systems necessitates inclusion of both curvature and non-Newtonian surface effects. In appropriate limits, our numerical results are validated against semi-analytical solutions. Our findings offer insights relevant to metal casting applications.
{"title":"Modelling viscoplastic interfacial flows inclusive of curvature effects","authors":"P.T. Griffiths , D. Xu , L. Davoust","doi":"10.1016/j.jnnfm.2025.105498","DOIUrl":"10.1016/j.jnnfm.2025.105498","url":null,"abstract":"<div><div>This study presents a theoretical and numerical investigation of interfacial flows of oxidised liquid metals in a shallow annular channel in the absence of inertial effects. For the first time, viscoplastic surface behaviour induced by oxidation is modelled using a bi-viscosity law within a framework that also accounts for interfacial curvature governed by the Young–Laplace equation. By solving a coupled bulk-surface flow system, the effects of surface rheology, contact angle, and dimensionless capillary length on surface velocity and surface shear rate profiles are quantified. Results highlight the competing influences of hydrophobicity and viscoplasticity on surface and bulk flow characteristics and demonstrate that accurate modelling of such systems necessitates inclusion of both curvature and non-Newtonian surface effects. In appropriate limits, our numerical results are validated against semi-analytical solutions. Our findings offer insights relevant to metal casting applications.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"346 ","pages":"Article 105498"},"PeriodicalIF":2.8,"publicationDate":"2025-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145222681","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 : 2025-09-27DOI: 10.1016/j.jnnfm.2025.105496
Thomasina V. Ball , A.F. Bonfils , Jerome A. Neufeld
We study the formation of wrinkles in a clamped viscoplastic plate overlying a thin viscous substrate, which is compressed horizontally. When the plate is purely viscous, the compressive force in the plate is constant and is set by the velocity boundary conditions. The wavelength of the emergent wrinkles depends on the thicknesses of the two layers and the ratio of the viscosities. As the domain length is reduced relative to the characteristic wavelength, the spatial profile and growth rate start to depend heavily on the domain length and imposed clamped boundary conditions. Introducing a yield stress to the plate initially increases the compressive force, proportional to the Bingham number, due to the requirement for the plate to be yielded throughout the domain. As the bending moments increase in the plate, the compressive force is relieved and a transition occurs where the plate begins to yield through bending rather than compression. During this transition, the plate is dominated by plugged, unyielded regions leading to localisation and the formation of straight-sided wrinkles.
{"title":"Wrinkling of a viscoplastic plate on a viscous substrate","authors":"Thomasina V. Ball , A.F. Bonfils , Jerome A. Neufeld","doi":"10.1016/j.jnnfm.2025.105496","DOIUrl":"10.1016/j.jnnfm.2025.105496","url":null,"abstract":"<div><div>We study the formation of wrinkles in a clamped viscoplastic plate overlying a thin viscous substrate, which is compressed horizontally. When the plate is purely viscous, the compressive force in the plate is constant and is set by the velocity boundary conditions. The wavelength of the emergent wrinkles depends on the thicknesses of the two layers and the ratio of the viscosities. As the domain length is reduced relative to the characteristic wavelength, the spatial profile and growth rate start to depend heavily on the domain length and imposed clamped boundary conditions. Introducing a yield stress to the plate initially increases the compressive force, proportional to the Bingham number, due to the requirement for the plate to be yielded throughout the domain. As the bending moments increase in the plate, the compressive force is relieved and a transition occurs where the plate begins to yield through bending rather than compression. During this transition, the plate is dominated by plugged, unyielded regions leading to localisation and the formation of straight-sided wrinkles.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"346 ","pages":"Article 105496"},"PeriodicalIF":2.8,"publicationDate":"2025-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145222682","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 : 2025-09-24DOI: 10.1016/j.jnnfm.2025.105497
Carlos Veiga Rodrigues , Francisco Vide , Alexandre M. Afonso , Fernando T. Pinho
A theoretical analysis of the energy equation for viscoelastic flows is performed, following the work of Peters and Baaijens [Peters GWM, Baaijens FPT, 1997 J. Non-Newt. Fluid Mech., 68:205–224], and aimed at extending it to deal with fluids having temperature-dependent and time-dependent fluid properties, which give rise to new terms in the transport equation that are not present in the original Peters and Baaijens work. Lastly, an application of the extended energy equation is carried out using the PTT network model.
根据Peters和Baaijens的工作，对粘弹性流动的能量方程进行了理论分析[Peters GWM， Baaijens FPT, 1997 J. Non-Newt.]流体机械。[j]，旨在将其扩展到处理具有温度依赖和时间依赖流体性质的流体，这在彼得斯和Baaijens的原始工作中没有出现的输运方程中产生了新的项。最后，利用PTT网络模型对扩展后的能量方程进行了应用。
{"title":"Note on the theoretical analysis of the energy equation for viscoelastic flows under non-isothermal material properties","authors":"Carlos Veiga Rodrigues , Francisco Vide , Alexandre M. Afonso , Fernando T. Pinho","doi":"10.1016/j.jnnfm.2025.105497","DOIUrl":"10.1016/j.jnnfm.2025.105497","url":null,"abstract":"<div><div>A theoretical analysis of the energy equation for viscoelastic flows is performed, following the work of Peters and Baaijens [Peters GWM, Baaijens FPT, 1997 J. Non-Newt. Fluid Mech., 68:205–224], and aimed at extending it to deal with fluids having temperature-dependent and time-dependent fluid properties, which give rise to new terms in the transport equation that are not present in the original Peters and Baaijens work. Lastly, an application of the extended energy equation is carried out using the PTT network model.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"346 ","pages":"Article 105497"},"PeriodicalIF":2.8,"publicationDate":"2025-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145222683","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}
We experimentally study the dynamics of a horizontal jet of a Newtonian fluid injected into a viscoplastic ambient fluid (Carbopol gel) to simulate jet cleaning in plug and abandonment operations of oil and gas wells. The jet flow is analyzed using high-speed imaging, planar laser induced fluorescence, and time-resolved tomographic particle image velocimetry techniques to capture concentration and velocity fields with high spatial and temporal resolution. By varying the Reynolds and Bingham numbers, we analyze three recently identified flow regimes, i.e., mixing, mushroom, and fingering, focusing on their mixing index, velocity fields, fluctuation intensity, half-radius, vorticity, Reynolds stresses, probability density functions, and statistical moments (skewness and kurtosis). In the mixing regime, velocity and vorticity symmetry, axisymmetric mixing, and dominant axial Reynolds stresses align with Newtonian empirical correlations. The mushroom regime shows slight asymmetry, reduced mixing from turbulence suppression by yield stress, and moderate turbulence, while the fingering regime features pronounced asymmetry, erratic fluctuations, and suppressed velocity due to viscoplastic resistance. Self-similarity analysis of velocity, concentration, and Reynolds stress profiles confirms strong scaling in the mixing regime, partial scaling in the mushroom regime, and deviations in the fingering regime, where viscoplastic effects disrupt jet structure and turbulence.
{"title":"Turbulence characteristic evolution in jets interacting with viscoplastic fluids","authors":"H. Hassanzadeh , M.H. Moosavi , I.A. Frigaard , S.M. Taghavi","doi":"10.1016/j.jnnfm.2025.105494","DOIUrl":"10.1016/j.jnnfm.2025.105494","url":null,"abstract":"<div><div>We experimentally study the dynamics of a horizontal jet of a Newtonian fluid injected into a viscoplastic ambient fluid (Carbopol gel) to simulate jet cleaning in plug and abandonment operations of oil and gas wells. The jet flow is analyzed using high-speed imaging, planar laser induced fluorescence, and time-resolved tomographic particle image velocimetry techniques to capture concentration and velocity fields with high spatial and temporal resolution. By varying the Reynolds and Bingham numbers, we analyze three recently identified flow regimes, i.e., mixing, mushroom, and fingering, focusing on their mixing index, velocity fields, fluctuation intensity, half-radius, vorticity, Reynolds stresses, probability density functions, and statistical moments (skewness and kurtosis). In the mixing regime, velocity and vorticity symmetry, axisymmetric mixing, and dominant axial Reynolds stresses align with Newtonian empirical correlations. The mushroom regime shows slight asymmetry, reduced mixing from turbulence suppression by yield stress, and moderate turbulence, while the fingering regime features pronounced asymmetry, erratic fluctuations, and suppressed velocity due to viscoplastic resistance. Self-similarity analysis of velocity, concentration, and Reynolds stress profiles confirms strong scaling in the mixing regime, partial scaling in the mushroom regime, and deviations in the fingering regime, where viscoplastic effects disrupt jet structure and turbulence.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"346 ","pages":"Article 105494"},"PeriodicalIF":2.8,"publicationDate":"2025-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145107993","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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