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

Effect of flow-inducing devices on the generation of viscoelastic fluid droplets 诱导流装置对粘弹性液滴产生的影响

IF 2.8 2区工程技术 Q2 MECHANICS

Journal of Non-Newtonian Fluid Mechanics

Pub Date : 2026-03-01 Epub Date: 2026-03-02 DOI: 10.1016/j.jnnfm.2026.105571

Runze Duan , Qiannan Huang , Chenyang Wei , Liansheng Liu , Yuanhe Yue , Qingfei Fu

Droplet generation is a fundamental fluid dynamic process critical to numerous applications in biomedicine, inkjet printing, food processing, and microfluidic systems. Achieving precious control over this process is important for improving the performance and efficiency of such systems. Compared to Newtonian fluids, viscoelastic fluids exhibit complex rheological behaviors arising from polymer chain entanglement and relaxation effects, which profoundly alter the droplet generation and breakup dynamics. In this study, we introduce a passive control strategy by incorporating a drainage device inside the nozzle to construct a drainage-assisted dripping system. The results show that, within the investigated polymer system, increasing molecular weight is associated with longer filament lengths, larger primary droplet volumes, and extended droplet generation periods. The introduction of the drainage device effectively mitigates these elastic effects by modifying the flow redistribution and upstream boundary conditions prior to breakup, rather than through direct control of elongational stresses. As a result, the filament breakup length is reduced and the generation of satellite droplets is suppressed under the present experimental conditions. Furthermore, the dimensionless length (L_s/L₀) and diameter (D_s/D₀) of the drainage device are key governing parameters within the investigated parameter range. An increase in L_s/L₀ leads to a reduction in the primary droplet volume, filament breakup length, and droplet generation period. In contrast, an increase in D_s/D₀ yields a slight decrease in droplet volume and filament length but prolongs the generation period. Notably, polymer solutions with higher elasticity exhibit stronger sensitivity to the geometric parameters of the drainage device under the present conditions. These findings demonstrate that by optimizing the drainage device geometry, elastic control over droplet size and generation frequency can be achieved without altering the fluid viscosity within the investigated system. This work provides new insights into the passive regulation of viscoelastic droplet generation and may offer useful guidance for the design and optimization of microfluidic, inkjet printing, and multiphase flow systems.

液滴的产生是一个基本的流体动力学过程，对生物医学、喷墨打印、食品加工和微流体系统的许多应用至关重要。实现对该过程的宝贵控制对于提高此类系统的性能和效率非常重要。与牛顿流体相比，粘弹性流体由于聚合物链的缠结和松弛效应而表现出复杂的流变行为，这深刻地改变了液滴的产生和破碎动力学。在本研究中，我们引入了一种被动控制策略，通过在喷嘴内加入排水装置来构建排水辅助滴水系统。结果表明，在所研究的聚合物体系中，分子量的增加与长丝长度、初生液滴体积和液滴生成周期的延长有关。通过改变破裂前的流动再分配和上游边界条件，排水装置的引入有效地减轻了这些弹性效应，而不是通过直接控制伸长应力。实验结果表明，在本实验条件下，灯丝断裂长度减小，卫星液滴的产生受到抑制。此外，排水装置的无因次长度（Ls/L0）和直径（Ds/D0）是研究参数范围内的关键控制参数。Ls/L0的增加导致初级液滴体积减小，细丝破裂长度减小，液滴生成周期缩短。相比之下，Ds/D0的增加使液滴体积和灯丝长度略有减少，但延长了生成周期。值得注意的是，在当前条件下，具有较高弹性的聚合物溶液对排水装置几何参数表现出更强的敏感性。这些发现表明，通过优化排水装置的几何形状，可以在不改变所研究系统内流体粘度的情况下实现对液滴尺寸和产生频率的弹性控制。这项工作为粘弹性液滴生成的被动调控提供了新的见解，并可能为微流体、喷墨打印和多相流系统的设计和优化提供有用的指导。

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引用次数: 0

Swimming dynamics of microorganisms near a wall in viscoelastic fluids 粘弹性流体中微生物在壁面附近的游动动力学

IF 2.8 2区工程技术 Q2 MECHANICS

Journal of Non-Newtonian Fluid Mechanics

Pub Date : 2026-03-01 Epub Date: 2026-02-03 DOI: 10.1016/j.jnnfm.2026.105565

Runyang Qiu, Fangyuan Peng, Minkang Zhang, Dingyi Pan, Zhaosheng Yu, Zhaowu Lin

Microorganisms in natural environments often navigate through non-Newtonian fluids under confinement that critically influences their locomotion dynamics. A direct-forcing fictitious domain method, coupled with the squirmer model, is employed to systematically investigate the swimming behaviors of microswimmers near a wall in Giesekus viscoelastic fluids. Four distinct behavioral modes are identified: scattering, oscillating, crawling, and hovering. Near planar walls, squirmers with strong stresslets demonstrate wall-trapped tendencies, with pullers predominantly exhibiting crawling behaviors while pushers display sustained oscillatory motions. Notably, the polymeric viscoelastic stress generates a torque opposite to that in the Newtonian case, which hinders the microswimmer’s escape from the wall. Furthermore, concave wall geometries substantially modify these behaviors through curvature-dependent hydrodynamic interactions, revealing a critical relationship between behavioral modes and geometric topology.

自然环境中的微生物经常在非牛顿流体中导航，这严重影响了它们的运动动力学。采用直接强迫虚拟域方法，结合蠕动模型，系统地研究了微游泳者在Giesekus粘弹性流体中靠近壁面的游动行为。确定了四种不同的行为模式：散射、振荡、爬行和悬停。在平面壁面附近，具有强应力层的蠕动器表现出壁面捕获倾向，其中拉力主要表现出爬行行为，而推力则表现出持续的振荡运动。值得注意的是，聚合物粘弹性应力产生的扭矩与牛顿情况相反，这阻碍了微游泳者从壁上逃脱。此外，凹壁几何通过曲率相关的流体动力相互作用极大地改变了这些行为，揭示了行为模式与几何拓扑之间的关键关系。

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引用次数: 0

U = 0? U = 0？

IF 2.8 2区工程技术 Q2 MECHANICS

Journal of Non-Newtonian Fluid Mechanics

Pub Date : 2026-01-01 Epub Date: 2025-11-19 DOI: 10.1016/j.jnnfm.2025.105530

Ian Frigaard

Yield stress fluids have the ability to withstand a shear stress while at rest, i.e. below the yield stress. Consequently, the zero solution has a wider range of application than in Newtonian hydrostatics. Alternatively, one could say that with yield stress fluids a new branch of hydrostatics is possible. This paper shows how in general zero flows are intuitively described using the yield number. It gives the general definition of a critical yield number, above which flows are static. The critical yield number also frequently defines a parametric domain in which the flow is nonlinearly stable, as is demonstrated. The mathematical concepts are introduced from the perspective of a reader who wishes to use a new toolbox and the main ideas are illustrated with a wide range of application flows and examples.

屈服应力流体在静止时具有承受剪切应力的能力，即低于屈服应力。因此，零解比牛顿流体静力学具有更广泛的应用范围。或者，有人可能会说，屈服应力流体是流体静力学的一个新分支。本文展示了如何在一般情况下用屈服数直观地描述零流。它给出了临界产量的一般定义，高于此值的流动是静态的。临界屈服数也经常定义一个参数域，其中流动是非线性稳定的，如所示。从希望使用新工具箱的读者的角度介绍了数学概念，并通过广泛的应用流程和示例说明了主要思想。

引用次数: 0

Modeling Rayleigh–Taylor instability in viscoelastic liquid film flow 粘弹性液膜流动中的瑞利-泰勒不稳定性建模

IF 2.8 2区工程技术 Q2 MECHANICS

Journal of Non-Newtonian Fluid Mechanics

Pub Date : 2026-01-01 Epub Date: 2025-11-19 DOI: 10.1016/j.jnnfm.2025.105531

Minzun He, Weiyang Jiang, Zijing Ding

This study presents a first-order weighted-residual model for viscoelastic thin-film flow on inverted substrates, incorporating van der Waals interactions. The model is derived via systematic scaling analysis, boundary-layer approximations, and a Galerkin weighted-residual method based on the Oldroyd-B constitutive framework. It achieves a balance between computational efficiency and accurate representation of viscoelastic effects. A notable feature is the ability to independently adjust the Deborah number (

D e

) and the retardation ratio (

r

), addressing the limitation of Benney-type models that depend only on the combined parameter

M = (1 - r) D e

. The model remains accurate for large

D e

. Analysis of the principal dimensionless parameters (

D e

,

S

,

r

,

A

,

G a

) clarifies the stability behavior: increasing

D e

enhances elastic instability, whereas a larger

r

weakens viscoelastic effects. The cutoff wavenumber

k_{c}

depends on gravity (

G a

), surface tension (

S

), and van der Waals forces (

A

), but not on

D e

or

r

. Validation against linearized Navier–Stokes (LNS) solutions and direct numerical simulations (DNS) shows closer agreement than the Benney-type model, particularly at high

D e

. The model also reproduces ultrathin-film rupture via cusp formation induced by van der Waals forces and predicts the scaling law

h_{min} \propto {(t_{r} - t)}^{1 / 5}

near rupture.

本研究提出了一个考虑范德华相互作用的一阶粘弹性薄膜流动的加权残差模型。该模型通过系统的尺度分析、边界层近似和基于Oldroyd-B本构框架的Galerkin加权残差法得到。它在计算效率和粘弹性效应的准确表示之间取得了平衡。一个显著的特点是能够独立调节Deborah数（De）和延迟比(r)，解决了benney型模型仅依赖于组合参数M=(1−r)De的局限性。对主要无量纲参数（De， S, r， A, Ga）的分析澄清了稳定性行为：增加De会增强弹性不稳定性，而较大的r会减弱粘弹性效应。截止波数kc取决于重力（Ga）、表面张力(S)和范德华力(A)，但与De或r无关。对线性化Navier-Stokes （LNS）解和直接数值模拟（DNS）的验证表明，与benney型模型更接近，特别是在高De时。该模型还通过范德华力诱导的尖点形成再现了超薄膜破裂，并预测了破裂附近的标度律hmin∝(tr−t)1/5。

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引用次数: 0

Vortex dynamics in converging-diverging pipes for weakly and moderately elastic polymer solutions 弱弹性和中等弹性聚合物溶液中聚散管中的涡旋动力学

IF 2.8 2区工程技术 Q2 MECHANICS

Journal of Non-Newtonian Fluid Mechanics

Pub Date : 2026-01-01 Epub Date: 2025-11-11 DOI: 10.1016/j.jnnfm.2025.105529

Aidar I. Kadyirov

The importance of extensional rheology to the flow structure in single and double converging-diverging (Cnv-Dvr) pipes has been observed experimentally. The aqueous solutions of 0.1 % polyacrylamide and 0.155 % Xanthan gum with the same shear viscosity but different extensional behavior were chosen as moderately and weakly elastic polymer solutions. For single Cnv-Dvr pipes with conical restriction rate of 2:1:2 it was observed that in a wide range of Weissenberg, Deborah and Reynolds numbers a vortex is generated in converging or diverging sections only, which depends on the type of a polymer solution. Similar tendency was found for double Cnv-Dvr pipes, except that both fluids generate a smaller vortex in the middle section (diverging-converging section). For all runs related to the polymer solution flows and conducted in the present study, the elastic forces predominate over inertial ones. The vortex formation for moderately elastic polymer solutions observed in double Cnv-Dvr pipes like in a single one leads to the axial velocity oscillations with an increase in amplitude with the flow rate up until the critical value. The emerging smaller vortex in the middle section does not change this behavior and oscillates with the same frequency. The location of vortex formation for weakly elastic polymer solution in both pipes is similar to Newtonian fluid.

通过实验观察了拉伸流变对单管和双管内流动结构的重要性。选择剪切粘度相同但拉伸性能不同的0.1%聚丙烯酰胺和0.155%黄原胶水溶液作为中弹性和弱弹性聚合物溶液。对于锥形限制率为2:1:2的Cnv-Dvr单管，我们观察到在较宽的Weissenberg、Deborah和Reynolds数范围内，只在收敛段或发散段产生涡流，这取决于聚合物溶液的类型。双Cnv-Dvr管道也有类似的趋势，只是两种流体在中间段（发散-收敛段）产生较小的涡。在本研究中进行的所有与聚合物溶液流动有关的运行中，弹性力比惯性力更重要。中等弹性聚合物溶液在双Cnv-Dvr管道中形成的旋涡与在单管道中一样，导致轴向速度振荡，且随着流速的增加而振幅增加，直至达到临界值。中间部分出现的较小的涡没有改变这种行为，并且以相同的频率振荡。弱弹性聚合物溶液在两种管道中的涡旋形成位置与牛顿流体相似。

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引用次数: 0

Corrigendum to “Natural convection within a non-uniformly heated cavity partly filled with a shear-thinning nanofluid and partly with air” [Journal of Non-Newtonian Fluid Mechanics 289 (2021) 104490] “部分充满剪切变薄纳米流体和部分充满空气的非均匀加热腔内的自然对流”的勘误表[非牛顿流体力学杂志289 (2021)104490]

IF 2.8 2区工程技术 Q2 MECHANICS

Journal of Non-Newtonian Fluid Mechanics

Pub Date : 2026-01-01 Epub Date: 2025-11-07 DOI: 10.1016/j.jnnfm.2025.105516

Asma Ouahouah , Nabila Labsi , Xavier Chesneau , Youb Khaled Benkahla

引用次数: 0

Approach to a similarity solution of the lubrication flow of an Oldroyd-B fluid through a hyperbolic pipe oldyd - b流体通过双曲管润滑流动的相似解的探讨

IF 2.8 2区工程技术 Q2 MECHANICS

Journal of Non-Newtonian Fluid Mechanics

Pub Date : 2026-01-01 Epub Date: 2025-11-05 DOI: 10.1016/j.jnnfm.2025.105519

John Hinch

Sialmas & Housiadas (2025), found a similarity solution of the Oldroyd-B equations for viscoelastic flow through a slowly varying axisymmetric contraction with a hyperbolic shape. We study whether inlet stresses decay onto this similarity solution before the end of the pipe, finding they do so only when a strain-rate based Deborah number is sufficiently small,

D e_{e} ≲ 1

.

Sialmas & Housiadas（2025）发现了Oldroyd-B方程的相似解，该方程通过缓慢变化的双曲形状轴对称收缩进行粘弹性流动。我们研究了入口应力是否在管道结束前衰减到这个相似解上，发现只有当基于应变率的黛博拉数足够小，Dee > 1时，它们才会衰减。

引用次数: 0

Friction factor for pulsatile flow of viscoelastic fluids in circular tubes and concentric annuli using a dynamic slip model at the walls 基于管壁动态滑移模型的粘弹性流体在圆管和同心环空中脉动流动的摩擦系数

IF 2.8 2区工程技术 Q2 MECHANICS

Journal of Non-Newtonian Fluid Mechanics

Pub Date : 2026-01-01 Epub Date: 2025-11-01 DOI: 10.1016/j.jnnfm.2025.105515

G. Barrera , J. Arcos , F. Méndez , O. Bautista

This work theoretically analyzes the influence of the slippage condition on the pulsatile flow of a viscoelastic fluid, whose rheological behavior follows the Jeffreys model, through circular and concentric annular tubes. A pulsatile pressure gradient causes the flow and a dynamic slip model is assumed on the walls of the tube to depend on the past states of the local wall shear stress, similar to the concept of the viscoelastic fluid memory, where the local state of the stress depends on the past deformation history to which the fluid particles are subject Hatzikiriakos (2012). As part of the assumptions, a periodic flow condition is considered, which is defined as the stage when the transient stage has finished. The hydrodynamics is obtained by solving the momentum equation, which is derived from a suitable combination of the Cauchy and Jeffreys constitutive equations, subject to the slip boundary condition that depends on the Jeffreys rheological model. The mathematical model is nondimensionalized, arising parameters that characterize the flow: the Womersley number

Wo

, the Deborah numbers

De

of the fluid, the slip relaxation number De_s associated to the dynamic slip boundary condition; the parameter

Λ

that represents the ratio between the relaxation and retardation times of the fluid; a parameter

κ

representing the ratio between the inner and outer radii of the annular tube; the slip parameters

β_{1}

and

β_{2}

related to the slippage at the walls. We illustrate the influence of the dimensionless parameters involved in the analysis through phase portrait diagrams that depict the dynamics of the flow. Based on the hydrodynamic field, we determine the instantaneous volumetric flow rate and evaluate the Poiseuille number as a function of the slip relaxation number. Additionally, we develop an asymptotic solution for the hydrodynamic field in the limit where

Wo ≪ 1

, which aids in understanding the flow dynamics.

本文从理论上分析了滑移条件对粘弹性流体在圆形和同心环形管中脉动流动的影响，粘弹性流体的流变行为遵循Jeffreys模型。脉动压力梯度导致管道壁上的流动和动态滑移模型取决于局部壁面剪切应力的过去状态，类似于粘弹性流体记忆的概念，其中应力的局部状态取决于流体颗粒受到的过去变形历史（Hatzikiriakos, 2012）。作为假设的一部分，考虑了周期流动条件，它被定义为瞬态阶段结束的阶段。流体力学是通过求解动量方程得到的，动量方程是由Cauchy和Jeffreys本构方程的适当组合导出的，并受到依赖于Jeffreys流变模型的滑移边界条件的约束。数学模型是非量纲化的，产生表征流动的参数：流体的Womersley数Wo、Deborah数De、与动态滑移边界条件相关的滑移松弛数Des；参数Λ表示流体的松弛时间与延迟时间之比；参数κ表示环形管内外半径之比；滑移参数β1和β2与壁面滑移有关。我们通过描述流动动力学的相肖像图来说明分析中涉及的无量纲参数的影响。在水动力场的基础上，确定了瞬时体积流量，并计算了滑移松弛数与泊泽维尔数的关系。此外，我们还开发了极限Wo≪1处的水动力场的渐近解，这有助于了解流动动力学。

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引用次数: 0

Single bubble dynamics in temperature-sensitive gelled propellants flowing through corrugated channels 温度敏感凝胶推进剂流过波纹通道的单泡动力学

IF 2.8 2区工程技术 Q2 MECHANICS

Journal of Non-Newtonian Fluid Mechanics

Pub Date : 2026-01-01 Epub Date: 2025-10-20 DOI: 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.

胶状推进剂的高粘度引起的气泡滞留对推进系统的燃烧稳定性和性能提出了重大挑战。为了解决这个问题，本研究研究了剪切减薄凝胶推进剂中单个气泡流过波纹通道的动态行为。采用流体体积（VOF）方法进行了数值模拟，采用改进的carau - yasuda模型来表示非牛顿粘度特性。分析了通道几何形状、温度和入口速度对气泡动力学和表观粘度的影响。结果表明，在梯形通道中气泡速度最高，其次是正弦通道和光滑通道。增大波纹振幅可以提高气泡速度，而温度升高则会降低气泡速度。在低进口速度下，气泡保持其形状；在中等速度下，它变形并恢复；在高速下，它分裂。这些发现为研究凝胶推进剂中的气泡行为提供了有价值的见解，并有助于推进系统设计的优化。

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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 : 2026-01-01 Epub 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