Journal of Non-Newtonian Fluid Mechanics最新文献_第3页

Inferring viscoplastic models from velocity fields: A physics-informed neural network approach 从速度场推断粘塑性模型：一种物理信息神经网络方法

IF 2.8 2区工程技术 Q2 MECHANICS

Journal of Non-Newtonian Fluid Mechanics

Pub Date : 2025-10-18 DOI: 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.

流体状物质无处不在，从活的生物组织到地质构造，从微米到公里的尺度都有。推断它们的流变特性仍然是一个主要的挑战，特别是当传统的流变学无法捕捉它们复杂的、三维的、通常是异质的行为时。系统尺寸、边界条件和其他材料特定的物理、化学或热约束加剧了这一困难。在这项工作中，我们探讨流变规律是否可以直接从流动观察推断。我们提出了一个物理信息神经网络（PINN）框架，旨在仅从速度场数据学习本构粘塑性规律。该方法采用神经网络插值速度场，通过自动微分计算速度梯度。这些梯度被用来估计控制守恒定律的残差，这隐含地依赖于未知的流变。我们通过最小化物理残差和观测数据的差异，共同优化本构模型和速度场表示。我们用Herschel-Bulkley、Carreau和Papanastasiou模型在不同流动条件下的数值模拟生成的合成速度场验证了我们的方法。即使在存在明显噪声的情况下，该算法也能可靠地推断流变参数。我们分析了推理性能对流动几何形状和采样的依赖，强调了数据集中剪切率分布的重要性。最后，我们探索了通过嵌入式模型选择进行模型不可知推理的初步策略，展示了pin在从候选模型中识别最合适的流变规律方面的潜力。这项研究说明了机器学习，特别是pinn，如何提高我们仅使用速度场数据来探测复杂流体流变学的能力，为计算流变学和材料表征的新方法铺平了道路。

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引用次数: 0

Transitional shear flow of elastic chains: A theoretical study based on molecular rheology 弹性链的过渡剪切流动：基于分子流变学的理论研究

IF 2.8 2区工程技术 Q2 MECHANICS

Journal of Non-Newtonian Fluid Mechanics

Pub Date : 2025-10-15 DOI: 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.

本研究考察了FENE-P和Rouse模型作为代表的粗粒度弹性链的时间依赖性能。该分析是在两种常规流变剪切流中进行的：在“开始”和“启动”阶段都考虑的阻力Couette流，以及压力驱动的Poiseuille流。本研究的主要目的是研究与剪切应力增长、第一正应力差、速度发展和结构演变有关的流变行为，包括端到端均方距离、旋转半径和弹性链的取向函数。为了实现这些分子模型，采用了类似connffessit的方法。首先，通过将结果与现有数据进行全面比较，验证了该方法的有效性，随后将其应用于不同的条件下，包括不同的剪切速率、链段数和链的可扩展性。该研究揭示了FENE-P链和Rouse链流变行为的根本区别，前者在流动下具有有限的可扩展性，而后者可以无限延伸。尽管圆管内的启动流动可能看起来很简单，但通过微观宏观框架应用这些模型可以获得新的结果，从而展示了该方法的多功能性。

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引用次数: 0

Experimental investigation of yield stress fluid flow in an abrupt 4:1 planar contraction using laser Doppler velocimetry: Effects of inertia and geometry 用激光多普勒测速法研究屈服应力流体在4:1突然平面收缩中的流动：惯性和几何的影响

IF 2.8 2区工程技术 Q2 MECHANICS

Journal of Non-Newtonian Fluid Mechanics

Pub Date : 2025-10-14 DOI: 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.

本文进行了屈服应力流体在宽高比为4:1的含突然收缩矩形通道内流动的实验研究。流动动力学分析是基于激光多普勒测速（LDV），它可以实现速度的局部表征。在收缩的上游、处和下游测量纵向和横向速度分量，以评估这种几何变化和惯性对流动的影响。纵向速度分量u的剖面突出表明，在收缩的角落存在一个死区，在那里可以识别出一条滑移线，并与收缩位于同一位置。确定了下游水流的建立长度，并提出了线性相关关系。在不同的流量和位置条件下，在通道中心观察到一个以恒定速度为特征的堵塞区域。横向速度分量，v，在整个区域保持接近零，除了在收缩区域，伸长效应变得明显。沿中轴线的速度分布分析显示，收缩的下游立即出现速度峰值，特别是在低流速时。伸长率在收缩时达到最大值，且该最大值与流量呈线性相关。还提出了一种描述壁面滑移速度的关系式。最后，通过建立摩擦系数f、欧拉数和雷诺数之间的相关性来完成研究，并在收缩的上游和下游区域进行评估。

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引用次数: 0

Investigating hemodynamic effects of consecutive arterial stenoses using an Eulerian granular two-phase model 用欧拉颗粒两相模型研究连续动脉狭窄的血流动力学影响

IF 2.8 2区工程技术 Q2 MECHANICS

Journal of Non-Newtonian Fluid Mechanics

Pub Date : 2025-10-10 DOI: 10.1016/j.jnnfm.2025.105508

Siddhartha Sankar Das, Dasari Abhiram, Swarup Kumar Mahapatra

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.

了解狭窄间长度（或间距）对双狭窄血管血流动力学的影响对于提高我们对心血管疾病及其治疗的认识至关重要。本研究采用两相欧拉颗粒模型，结合动力学理论来捕捉红细胞（RBC）颗粒力学，研究75%狭窄度（DOS）双狭窄动脉血管的血流动力学。为了验证我们的方法，我们将其与Yeleswarapu等人（1998）报道的体外实验速度曲线进行了基准比较。与其他测试方法（包括单相（牛顿）和两相（欧拉-欧拉双流体）模型）相比，当前模型的最大偏差为7.24%，具有更好的一致性。我们的研究结果表明，较短的狭窄间距导致速度梯度升高，加剧了局部惯性效应。相反，更长的间距可以使流体恢复更多的距离并重新分层，从而稳定速度剖面。狭窄的存在明显破坏了典型的被血浆包围的中央红细胞核心。具体来说，在狭窄间的短长度处，来自第一个狭窄的受干扰的血流缺乏足够的距离来重新建立剪切梯度驱动的RBC迁移。这抑制了明确的核心红细胞压积的形成，导致红细胞分布更加分散或偏斜。此外，短的狭缝长度促进了更强的流动相互作用和下游区域持续螺旋涡的产生。较大的狭窄段长度有利于部分再层压化和涡消散，导致下游螺旋度降低，向更有组织的流动过渡。面积平均壁剪应力（AWSS）随狭窄段长度的减小而增大，特别是在狭窄的喉部。值得注意的是，该研究还表明，与我们的两相方法相比，单相牛顿模型更能预测流动分离和再循环。总的来说，这项研究强调了两相欧拉颗粒模型在精确模拟狭窄动脉内复杂血流动力学方面的能力，为研究其他复杂生物系统的血流动力学提供了潜在的扩展。

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引用次数: 0

Mitigating degradation-induced artifacts in rheological modeling of biopolymers using time-resolved rheology 使用时间分辨的流变学减轻生物聚合物流变建模中降解诱导的伪影

IF 2.8 2区工程技术 Q2 MECHANICS

Journal of Non-Newtonian Fluid Mechanics

Pub Date : 2025-10-10 DOI: 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.

可生物降解聚合物的流变分析通常因测试过程中的结构突变和热降解而变得复杂，导致数据不准确和建模不可靠。这些影响在常规的小振幅振荡剪切（SAOS）实验中尤为明显，因为这些实验需要长时间暴露在高温下。在本研究中，介绍了一种基于时间分辨流变学（TRR）的替代方法，以最大限度地减少降解的影响并分离固有的流变行为。通过捕获不同时间尺度的数据，该方法将降解动力学与流变响应解耦，从而能够构建更精确的流动曲线和材料函数。通过将该方法与几种聚羟基烷酸盐的传统SAOS协议进行比较，验证了该方法的有效性。我们的研究结果表明，基于trr的测量结果可以更可靠地预测粘弹性特性，包括松弛模量和启动剪切粘度。数据质量的提高使得本构方程建模的拟合效果更好。该方法为流变学测试提供了一种更有效和抗降解的策略，对优化生物可降解聚合物的加工和性能具有重要意义。

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引用次数: 0

Modelling viscoplastic interfacial flows inclusive of curvature effects 包含曲率效应的粘塑性界面流动建模

IF 2.8 2区工程技术 Q2 MECHANICS

Journal of Non-Newtonian Fluid Mechanics

Pub Date : 2025-09-27 DOI: 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.

本文对氧化液态金属在没有惯性效应的浅环形通道中的界面流动进行了理论和数值研究。第一次，由氧化引起的粘塑性表面行为在一个框架内使用双粘度定律进行建模，该框架也考虑了由Young-Laplace方程控制的界面曲率。通过求解一个体-面耦合流动系统，量化了表面流变性、接触角和无因次毛管长度对表面速度和表面剪切速率的影响。结果强调了疏水性和粘塑性对表面和体积流动特性的竞争影响，并表明此类系统的准确建模需要包括曲率和非牛顿表面效应。在适当的范围内，我们的数值结果对半解析解进行了验证。我们的发现提供了与金属铸造应用相关的见解。

引用次数: 0

Wrinkling of a viscoplastic plate on a viscous substrate 粘塑性板在粘性基材上起皱

IF 2.8 2区工程技术 Q2 MECHANICS

Journal of Non-Newtonian Fluid Mechanics

Pub Date : 2025-09-27 DOI: 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.

我们研究了夹紧粘塑性板上的薄粘性基材，这是水平压缩皱褶的形成。当板为纯粘性时，板内的压缩力是恒定的，由速度边界条件确定。出现皱纹的波长取决于两层的厚度和粘度的比例。随着畴长相对于特征波长的减小，空间轮廓和增长率开始严重依赖于畴长和施加的箝位边界条件。由于要求板在整个区域内屈服，向板引入屈服应力最初会增加与宾汉姆数成正比的压缩力。当板中的弯矩增加时，压缩力被解除，并且在板开始通过弯曲而不是压缩屈服的地方发生转变。在这一转变过程中，板块主要由堵塞的、未屈服的区域主导，导致局部化和直边褶皱的形成。

引用次数: 0

Note on the theoretical analysis of the energy equation for viscoelastic flows under non-isothermal material properties 非等温材料特性下粘弹性流动能量方程的理论分析注记

IF 2.8 2区工程技术 Q2 MECHANICS

Journal of Non-Newtonian Fluid Mechanics

Pub Date : 2025-09-24 DOI: 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。

引用次数: 0

Turbulence characteristic evolution in jets interacting with viscoplastic fluids 射流与粘塑性流体相互作用的湍流特性演化

IF 2.8 2区工程技术 Q2 MECHANICS

Journal of Non-Newtonian Fluid Mechanics

Pub Date : 2025-09-13 DOI: 10.1016/j.jnnfm.2025.105494

H. Hassanzadeh , M.H. Moosavi , I.A. Frigaard , S.M. Taghavi

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.

实验研究了将牛顿流体注入粘塑性环境流体（Carbopol凝胶）的水平射流动力学，以模拟油气井封堵和弃井作业中的射流清洗。利用高速成像、平面激光诱导荧光和时间分辨层析粒子图像测速技术对射流进行分析，以获得高时空分辨率的浓度场和速度场。通过改变雷诺数和宾厄姆数，我们分析了最近发现的三种流动形式，即混合流、蘑菇流和指指流，重点研究了它们的混合指数、速度场、波动强度、半半径、涡度、雷诺应力、概率密度函数和统计矩（偏度和峰度）。在混合状态下，速度和涡度对称、轴对称混合和主导轴向雷诺应力与牛顿经验相关。蘑菇模式表现出轻微的不对称，屈服应力抑制湍流导致的混合减少，湍流适度，而指法模式则表现出明显的不对称、不稳定波动和粘塑性阻力导致的速度抑制。速度、浓度和雷诺应力分布的自相似分析证实了混合状态下的强结垢，蘑菇状态下的部分结垢，指法状态下的偏差，粘塑性效应破坏了射流结构和湍流。

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引用次数: 0

Erratum to “A theory of die-swell revisited” 《重新审视死亡膨胀理论》的勘误

IF 2.8 2区工程技术 Q2 MECHANICS

Journal of Non-Newtonian Fluid Mechanics

Pub Date : 2025-09-09 DOI: 10.1016/j.jnnfm.2025.105495

Randy H. Ewoldt

引用次数: 0