Journal of Non-Newtonian Fluid Mechanics最新文献

{"title":"Equilibrium position and rotational behaviours of spheroid in an inertial rectangular microchannel flow of Oldroyd-B viscoelastic fluid","authors":"Xiao Hu ,&nbsp;Jianzhong Lin ,&nbsp;Zhaosheng Yu ,&nbsp;Zhaowu Lin ,&nbsp;Jingyu Cui ,&nbsp;Yan Xia","doi":"10.1016/j.jnnfm.2025.105431","DOIUrl":"10.1016/j.jnnfm.2025.105431","url":null,"abstract":"<div><div>Equilibrium position and rotational behaviours of spheroid in an inertial rectangular microchannel flow of Oldroyd-B viscoelastic fluid is studied by the direct forcing/fictitious domain method. The results show that there are five kinds of equilibrium positions and four (three) kinds of rotational behaviours for the elasto-inertial migration of prolate (oblate) spheroids in an inertial rectangular channel flow. The spheroids gradually change to the corner (CO), channel centreline (CC), near corner (NCO), near channel centre (NCC) and bisector of the long wall (BLW) equilibrium positions as the elastic number decreases, the NCO and NCC equilibrium positions are newly found in the present works. When the fluid elasticity is large, only the large sphere displays the anomalous off-centreline NCC equilibrium position. With increasing the fluid inertia, the induced lateral migration velocity near the particle is enhanced, and the induced streamlines push all particles away from the CC equilibrium position. Spherical particles exhibit the highest induced velocity, then followed by the oblate spheroids, while prolate spheroids induce the lowest lateral migration velocity and consistently exhibit the closest distance to the channel centre. The particles are closer to the channel centre with decreasing the particle size, and with increasing the fluid elasticity. Those results are useful for designing a microfluidic chip with high separation efficiency.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"341 ","pages":"Article 105431"},"PeriodicalIF":2.7,"publicationDate":"2025-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143923750","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Control of viscoplastic fluid dynamics in superhydrophobic channels with asymmetric groove configurations","authors":"A. Joulaei ,&nbsp;H. Rahmani ,&nbsp;S.M. Taghavi","doi":"10.1016/j.jnnfm.2025.105420","DOIUrl":"10.1016/j.jnnfm.2025.105420","url":null,"abstract":"<div><div>We study the plane Poiseuille flow of viscoplastic fluids in channels with asymmetric superhydrophobic (SH) walls featuring transverse groove configurations in the thin channel limit. We use OpenFOAM simulations and the Papanastasiou regularization method to approximate the Bingham model. Focusing on variations in the upper SH wall’s characteristics, we explore the effects of slip number (<span><math><msub><mrow><mi>b</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>), groove periodicity length (<span><math><msub><mrow><mi>ℓ</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>), slip area fraction (<span><math><msub><mrow><mi>φ</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>), and Bingham number (<span><math><mi>B</mi></math></span>) on flow dynamics, flow metrics and unyielded center plug morphology. We find that increasing <span><math><msub><mrow><mi>b</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>, <span><math><msub><mrow><mi>φ</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>, and <span><math><msub><mrow><mi>ℓ</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> enhances slip velocity on the upper SH wall and reduces the normalized plug area (<span><math><mrow><mi>A</mi><mo>/</mo><msub><mrow><mi>A</mi></mrow><mrow><mn>0</mn></mrow></msub></mrow></math></span>) up to <span><math><mrow><msub><mrow><mi>φ</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>=</mo><mn>0</mn><mo>.</mo><mn>5</mn></mrow></math></span>, while higher <span><math><mi>B</mi></math></span> amplifies flow asymmetry, shifting and breaking center plugs. By introducing the concept of <em>slippery equivalent systems</em>, we demonstrate that varying groove configurations can yield identical effective slip lengths (<span><math><msub><mrow><mi>χ</mi></mrow><mrow><mi>T</mi></mrow></msub></math></span>) with distinct plug morphologies, enabling precise control of viscoplastic fluid dynamics. We derive a simplified model to predict <span><math><msub><mrow><mi>χ</mi></mrow><mrow><mi>T</mi></mrow></msub></math></span> and <span><math><mrow><mi>A</mi><mo>/</mo><msub><mrow><mi>A</mi></mrow><mrow><mn>0</mn></mrow></msub></mrow></math></span>, identifying a critical threshold at <span><math><mrow><mi>A</mi><mo>/</mo><msub><mrow><mi>A</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>≈</mo><mn>0</mn><mo>.</mo><mn>68</mn></mrow></math></span> for regime transitions between unbroken (Regime I) and broken (Regime II) center plugs, leading to a six-dimensional manifold equation for classifying these regimes across parameter space.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"341 ","pages":"Article 105420"},"PeriodicalIF":2.7,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143869095","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Flow of a two-dimensional liquid foam: Impact of surfactant type and boundary conditions","authors":"Farshad Nazari ,&nbsp;Andrei Potanin ,&nbsp;Hadi Mohammadigoushki","doi":"10.1016/j.jnnfm.2025.105417","DOIUrl":"10.1016/j.jnnfm.2025.105417","url":null,"abstract":"<div><div>In this study, we experimentally investigate the rheological and flow behavior of two-dimensional (2D) monodisperse aqueous foams, sheared between parallel plates using a custom-made rheo-optical apparatus with smooth and roughened walls. The foams were prepared using two commercially available detergents — Foam 1 and Foam 2 — while maintaining similar bubble sizes and liquid fractions. The linear viscoelastic results reveal that the Foam 1 consistently exhibits higher elastic and loss moduli than the Foam 2, regardless of boundary conditions, with roughened walls further enhancing these moduli in both foams. Additionally, the Foam 1 shows a lower viscoelastic relaxation frequency compared to the Foam 2, indicating a less mobile interface for the Foam 1. In the non-linear regime, significant differences were observed. Under smooth boundary conditions, Foam 2 exhibits yield stress behavior, whereas Foam 1 does not, despite having higher viscous stresses. The viscous stress in the Foam 1 scales with the capillary number as <span><math><mrow><msub><mrow><mi>τ</mi></mrow><mrow><mi>w</mi></mrow></msub><mo>∝</mo></mrow></math></span> Ca<span><math><msup><mrow></mrow><mrow><mn>0</mn><mo>.</mo><mn>5</mn></mrow></msup></math></span>, while for the Foam 2, the scaling depends on the boundary conditions: <span><math><mrow><msub><mrow><mi>τ</mi></mrow><mrow><mi>w</mi></mrow></msub><mo>∝</mo></mrow></math></span> Ca<span><math><msup><mrow></mrow><mrow><mn>0</mn><mo>.</mo><mn>85</mn></mrow></msup></math></span> for smooth walls and <span><math><mrow><msub><mrow><mi>τ</mi></mrow><mrow><mi>w</mi></mrow></msub><mo>∝</mo></mrow></math></span> Ca<span><math><msup><mrow></mrow><mrow><mn>0</mn><mo>.</mo><mn>65</mn></mrow></msup></math></span> for roughened walls. These variations in rheological behavior are attributed to differences in surfactant chemistry, leading to different interface mobilities, with the Foam 1 having a less mobile interface compared to the Foam 2.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"339 ","pages":"Article 105417"},"PeriodicalIF":2.7,"publicationDate":"2025-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143823802","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unusual rheological behavior of a moderately entangled telechelic polymer and hollow glass microsphere suspension via hydrogen bonding interactions","authors":"Praveen Sreenivasan ,&nbsp;Srikanth Billa ,&nbsp;Sangram Kesari Rath ,&nbsp;Debdatta Ratna ,&nbsp;Santanu Chattopadhyay","doi":"10.1016/j.jnnfm.2025.105419","DOIUrl":"10.1016/j.jnnfm.2025.105419","url":null,"abstract":"<div><div>The understanding of rheological behavior of non-Brownian hard sphere suspensions is of importance from both the fundamental and applied perspectives. This is owing to their ubiquitous use in industry for many applications. However, most of the studies reported in literature pertain to non-colloidal hard sphere suspensions in a Newtonian matrix. In the present work, we report the rheological response of hollow glass microspheres (HGMs) suspended in a moderately entangled telechelic polymer of hydroxyl terminated polybutadiene (HTPB) across a wide concentration range i.e., volume fraction, <em>ɸ</em> varying from 0.07 to 0.6. Steady state and small amplitude oscillatory rheology (SAOR) measurements of the suspensions revealed a significant departure of the rheological response from that of non-Brownian hard sphere suspensions. The salient findings of the study are (a) pronounced shear thinning (b) increased storage and loss moduli with increased HGM content (c) low frequency storage moduli plateau across concentrations (d) percolation at <em>ɸ =</em>0.49–0.51 of HGM (e) significant difference in the high frequency dynamic modulus between HTPB and suspensions at <em>ɸ &gt;</em> 0.5. Some of these rheological features resemble that of colloidal or Brownian suspensions and are suggestive of formation of network or gel-like structure. We invoke the role of HTPB-HGM interaction (FTIR spectroscopy), morphology of the suspensions (optical microscopy), plausible immobilization of telechelic chains on surface of HGM, entangled state of the telechelic as the mechanistic origins of the observed unusual rheological behavior of the studied suspensions. We posit that the present study is an important addition to experimental investigations in the field of hard sphere dispersions.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"339 ","pages":"Article 105419"},"PeriodicalIF":2.7,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143843176","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Simulation of the extensional deformation of a drop with an elastoviscoplastic interface","authors":"M.A. Carrozza ,&nbsp;M. Hütter ,&nbsp;L.G.B. Bremer ,&nbsp;P.D. Anderson ,&nbsp;M.A. Hulsen","doi":"10.1016/j.jnnfm.2025.105408","DOIUrl":"10.1016/j.jnnfm.2025.105408","url":null,"abstract":"<div><div>A numerical implementation of two-phase flows of Newtonian fluids with a non-linear viscoelastic interface is validated and applied to the case of uniaxial extension of a drop in a matrix fluid. Second-order convergence in space and time is obtained with a Lagrangian-based interface tracking finite element method. The flow problem is analysed using dimensionless groups based on the relative magnitudes of the viscoelastic interfacial extra stress, the interfacial tension and the viscous stress of the bulk fluids. After fitting the intrinsic viscoelastic stress–strain behaviour of interfaces in shear to experimental results from the literature, the influence of interfacial rheology on the drop shape and interfacial stress is investigated. The drop shape is not significantly influenced by the viscoelastic properties of the interface if the interfacial viscoelastic stress, interfacial tension and bulk viscous stress are of the same order of magnitude. However, the interface develops distinct stress profiles for varying interfacial viscoelastic properties. For relatively large viscoelastic interface stress compared to interfacial tension and bulk viscous stress, simulations become unstable. Eventually, the interfacial viscoelastic stress exceeds the interfacial tension and bulk viscous stress, and possibly buckling of the interface occurs, caused by compressive stresses at the drop tip.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"339 ","pages":"Article 105408"},"PeriodicalIF":2.7,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143783703","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bingham flow development in annular tubes in the presence of wall slip","authors":"Evgenios Gryparis ,&nbsp;Alexandros Syrakos ,&nbsp;Georgios C. Georgiou","doi":"10.1016/j.jnnfm.2025.105418","DOIUrl":"10.1016/j.jnnfm.2025.105418","url":null,"abstract":"<div><div>The development of Bingham flow in concentric annular tubes in the presence of wall slip is investigated. It is assumed that slip occurs along both cylinders, following Navier's law, which states that the slip velocity is proportional to the wall shear stress. The open-source finite element software FEniCS is used for the numerical simulations along with the Papanastasiou regularization for the constitutive equation. To correctly determine the entrance region, various definitions of the development length are considered. In addition to the standard definition, which is based on the maximum velocity development, and the global development length, alternative definitions based on the development of the wall shear stresses and of the velocity at the two yield radii are considered. The combined effects of slip, yield stress and inertia on the different development lengths are systematically investigated. The yielded and unyielded zones are also determined using the von Mises criterion. The numerical results show that the standard development length fails to accurately capture the entrance region, even in the case of Newtonian flow with no-slip, and that the inner wall shear stress and yield lengths are also inadequate. The global and the outer wall shear stress and yield development lengths, which can be up to four times bigger than the standard development length, are more reliable. In agreement with previous studies, the development lengths are monotonically increasing with the Reynolds and Bingham numbers. As wall slip becomes stronger these reliable development lengths increase only initially reaching a maximum and then they are abruptly reduced to zero as the slip number approaches the critical value corresponding to sliding (unyielded) motion.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"339 ","pages":"Article 105418"},"PeriodicalIF":2.7,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143760470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermo-hydraulic perspectives of non-Newtonian channel flow with active flow modulation: A CFD study","authors":"Fahim Tanfeez Mahmood ,&nbsp;Arpita Das ,&nbsp;Taspia Shawkat Chowdhury ,&nbsp;Mohammad Nasim Hasan","doi":"10.1016/j.jnnfm.2025.105416","DOIUrl":"10.1016/j.jnnfm.2025.105416","url":null,"abstract":"<div><div>This study aims to numerically explore the influence of active flow modulators on thermo-hydraulic characteristics of channel flow with non-Newtonian power-law fluid, also known as Generalized Newtonian Fluid (GNF). The upper and lower walls of the channel under consideration are heated isothermally, while at the inlet a channel flow with Poiseuille fluid flow profile is imposed, influenced by an active flow modulator, namely an oscillating blade positioned along the channel centreline. Within the Arbitrary Lagrangian-Eulerian framework, the associated flow and thermal fields are solved using the Galerkin finite element method. The channel's hydrodynamic state is assessed in relation to the Reynolds number variation (50 ≤ <em>Re</em> ≤ 150), for various non-Newtonian fluids as represented by the power-law index variation (0.6 ≤ <em>n</em> ≤ 1.2). Furthermore, the corresponding dimensionless oscillating frequency (<em>N*</em>) and channel blockage ratio (<em>B</em>) are changed in order to investigate the impact of the flow modulator. The evolution of temperature and flow fields as well as heat transfer performance metrics, such as local, spatially and time averaged Nusselt numbers, have all been taken into consideration while evaluating the characteristics of the system. The obtained results indicate that the Reynolds number and associated flow obstruction have a significant impact on the flow modulator's efficacy. For pseudoplastic fluids (<em>n</em> = 0.6), thermal oscillations can be observed, which are brought on by the oscillating modulator's periodic shedding of vortices. While pseudoplastic fluid might improve heat transfer, especially at greater blockage ratios, the situation is reversed when the associated pressure drop is taken into account.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"339 ","pages":"Article 105416"},"PeriodicalIF":2.7,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143799596","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}

{"title":"Viscoelasticity-contrast driven electrohydrodynamic behaviour of a droplet-suspended-in-a-confined-liquid configuration","authors":"Pulak Gupta ,&nbsp;Purbarun Dhar ,&nbsp;Devranjan Samanta","doi":"10.1016/j.jnnfm.2025.105406","DOIUrl":"10.1016/j.jnnfm.2025.105406","url":null,"abstract":"<div><div>We present an approximate analytical model (without compromise on the physics) of the electrohydrodynamics (EHD) of a confined leaky dielectric, non-Newtonian viscoelastic droplet suspended in a surrounding medium of similar characteristics. The analysis considers the Stokes flow regime through a small deformation formulation. The viscoelastic behaviour is realized by coupling the Cauchy momentum equation with the upper convected Maxwell (UCM) model. Since the study is limited to low electric field intensities, the governing Weissenberg number (Wi) <span><math><mo>≤</mo></math></span> 1. We consider various combinations of the droplet and the surrounding, viz. NN-N, N-NN, and NN-NN cases. A thorough comparison with the N-N case is conducted. Here, ‘N’ represents Newtonian and ‘NN’ represents non-Newtonian. The solution put forward is validated with experimental observations in literature and works successfully in the regime of low electric field strength. We show that, for an unconfined domain, the deformation is maximum for the N-N case and least for the N-NN case, thus establishing the role of viscoelasticity-contrast. For the confined domain, we have also observed shape reversal in N-NN and NN-NN cases at higher confinement (<span><math><mi>α</mi></math></span>) and lower electro-rheological parameter (<span><math><mi>δ</mi></math></span>). For NN-N, the deformation is greater compared to the N-N case beyond a critical <span><math><mi>α</mi></math></span>. We also report the streamline patterns within the droplet and in the surrounding medium for various cases and for different confinement. The findings reveal shape reversal phenomena in confined viscoelastic cases, and provide insights into the EHD with fluidic confinement, offering potential avenues for the design and functionality of microfluidic devices.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"338 ","pages":"Article 105406"},"PeriodicalIF":2.7,"publicationDate":"2025-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143680337","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}

{"title":"Features and limitations of recent elastoviscoplastic constitutive models under Large Amplitude Oscillatory Shear (LAOS)","authors":"Rishav Agrawal ,&nbsp;Esther García-Tuñón ,&nbsp;Robert J. Poole ,&nbsp;Cláudio P. Fonte","doi":"10.1016/j.jnnfm.2025.105407","DOIUrl":"10.1016/j.jnnfm.2025.105407","url":null,"abstract":"<div><div>Elastoviscoplastic (EVP) models are becoming more widely adopted to investigate the deformation and flow of yield stress materials for various applications. In this work, we investigate EVP models, primarily the Saramito model but also the recently developed Kamani–Donley–Rogers (KDR) model, under Large Amplitude Oscillatory Shear (LAOS) tests using Fourier Transform (FT) rheology, dissipation ratio (<span><math><mi>ϕ</mi></math></span>) analysis and the Sequence of Physical Processes (SPP) framework. A detailed parametric study has been conducted for the Saramito model for a wide range of values of the relevant non-dimensional parameters – Bingham, Weissenberg and Deborah numbers. We also compare the Saramito and KDR models for a particular set of conditions and compare them with experimental data for Pluronic F127 hydrogel, a yield stress fluid commonly used in 3D printing. The parametric study of the Saramito model reveals a universal scaling for the onset of purely elastic behaviour, which shows dependence on <em>both</em> Bingham and Weissenberg numbers. Moreover, we demonstrate that although both EVP models can predict the ‘yielding’ process, the KDR model provides a better agreement with rheological data for Pluronic F127. The KDR also performs better in predicting associated EVP behaviour compared to the Saramito model, e.g. gradual change in the storage and loss moduli and the <span><math><mi>ϕ</mi></math></span> values near the onset of yielding. However, neither model could fully capture higher harmonics, shapes of the Lissajous-Bowditch curves and the intra-cycle rheological transitions when compared to experimental data. In addition to the LAOS measurements, further tests under different flow conditions of the recently-developed KDR model against experimental data for yield stress fluids are required to assess its capabilities in capturing the full spectrum of EVP behaviours.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"338 ","pages":"Article 105407"},"PeriodicalIF":2.7,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143680338","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Atomizing high-viscosity non-Newtonian fluids with the ACLR nozzle: Correlation between internal flow and external spray instabilities","authors":"Miguel Ángel Ballesteros Martínez,&nbsp;Prithika Roy,&nbsp;Juan Nicolás Solano Alarcón,&nbsp;Volker Gaukel","doi":"10.1016/j.jnnfm.2025.105405","DOIUrl":"10.1016/j.jnnfm.2025.105405","url":null,"abstract":"<div><div>Spray drying is a widely used method for producing food powders in large quantities, but it also has a high energy demand. To address this, one can increase the solid content of liquid feeds, although this, in turn, poses the challenge of atomizing high-viscosity liquids into fine droplets. The Air-Core-Liquid-Ring (ACLR) nozzle offers a potential solution for the atomization by inducing air and creating an annular flow inside the nozzle. Nevertheless, a challenge of this design is that it tends to present internal instabilities. This study investigates how feed viscosities up to 3 Pa·s, and feed dry-matter contents up to 57 % wt., influence the internal flow conditions and the resulting spray performance, i.e., the droplet size distribution and the spray angle. The results show that, while internal instabilities increment with increasing viscosities, the ACLR can seemingly achieve atomization with viscosities as high as 3 Pa·s, even at, compared to pressure swirl nozzles, low pressures (7 bar) and low air-to-liquid mass ratios (0.8). Nonetheless, a fraction of droplets over 500 µm remains, which needs to be addressed through higher ALRs or a geometrical optimization of the nozzle, before the nozzle can be considered for industrial applications. Additionally, we showed that the internal flow and the external spray instabilities can be correlated with each other. This confirms that any future studies attempting to increase the spray stability of the ACLR nozzle can focus on only one of these factors, and reasonably expect that the others will also improve.</div></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"338 ","pages":"Article 105405"},"PeriodicalIF":2.7,"publicationDate":"2025-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143580629","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}