Journal of Non-Newtonian Fluid Mechanics最新文献

{"title":"Rheo-optics of giant micelles: SALS patterns of cetyltrimethylammonium tosylate solutions in presence of sodium bromide","authors":"Moisés Romero-Ureña , Luis Medina-Torres , Octavio Manero , J. Esteban López-Aguilar","doi":"10.1016/j.jnnfm.2024.105286","DOIUrl":"10.1016/j.jnnfm.2024.105286","url":null,"abstract":"<div><p>In this work, we present a systematic study based on Small-Angle Light Scattering (SALS) patterns of the simple shear flow response of semi-diluted solutions of cetyltrimethylammonium tosylate (CTAT; 5.5 <span><math><mrow><mi>w</mi><mi>t</mi><mo>.</mo><mtext>%</mtext></mrow></math></span> - 0.12 M) in the presence of sodium bromide (NaBr) at different <span><math><mrow><mrow><mo>[</mo><mi>N</mi><mi>a</mi><mi>B</mi><mi>r</mi><mo>]</mo></mrow><mo>=</mo><mrow><mo>{</mo><mn>0</mn><mo>,</mo><mn>0</mn><mo>.</mo><mn>12</mn><mo>,</mo><mn>0</mn><mo>.</mo><mn>19</mn><mo>,</mo><mn>0</mn><mo>.</mo><mn>25</mn><mo>,</mo><mn>0</mn><mo>.</mo><mn>3</mn><mo>}</mo></mrow></mrow></math></span> M concentrations. We evidence a relationship between rheological and light scattering data that reveals a transition into a fast-breaking regime in the dynamics of wormlike micelles formed by the CTAT/NaBr system (Macías et al., 2011; Fierro et al., 2021). This transition into a micellar fast-breaking regime with salt addition (<span><math><mrow><mrow><mo>[</mo><mi>N</mi><mi>a</mi><mi>B</mi><mi>r</mi><mo>]</mo></mrow><mo>≥</mo><mn>0</mn></mrow></math></span>) appears marked by the following features: (i) a decrease in the relaxation time of the material <span><math><msub><mrow><mi>λ</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span>, accompanied by (ii) a decrease of the viscosity level at low shear rates <span><math><msub><mrow><mi>η</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span> (Macías et al., 2011; Fierro et al., 2021; Schubert et al., 2003; Alkschbirs et al., 2015; Bandyopadhyay et al., 2003). With these, (iii) the formation of butterfly-like patterns is recorded originating from concentration fluctuations, evolution that is accompanied by: (iv) shear banding in the form of non-monotonic flow curves and (v) slow oscillatory transient responses in start-up flow tests captured theoretically with the Bautista–Manero–Puig (BMP) model. In addition, the Cox–Merz rule is fulfilled at molar salt-to-surfactant ratios of <span><math><mrow><mi>R</mi><mo>≥</mo><mn>1</mn><mo>.</mo><mn>5</mn></mrow></math></span>. This results in shorter structure-recovery time-scales than the characteristic-time of the flow (Macías et al., 2011; Fierro et al., 2021; Manero et al., 2002). In the case of the elastic modulus <span><math><msub><mrow><mi>G</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span>, the variation was small, which suggests a transition from an entangled to a multiconnected network, as suggested by Kadoma & van Egmond (1997), Kadoma et al. (1997) and Fierro et al. (2021). <em>From a theoretical perspective</em>, we provide predictions for the shear–stress and the first normal-stress growth coefficients in transient start-up simple shear flow using the BMP model. Here, banding <span><math><mi>R</mi></math></span>=1.5 solutions display overshot responses at relatively high shear rates (<span><math><mrow><mover><mrow><mi>γ</mi></mrow><mrow><mo>̇</mo></mrow","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"331 ","pages":"Article 105286"},"PeriodicalIF":2.7,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141784724","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 fiber orientation through a finite element approach to solve the Fokker–Planck equation","authors":"Nazih Assaad Al Ayoubi ,&nbsp;Hugues Digonnet ,&nbsp;Luisa Silva ,&nbsp;Christophe Binetruy ,&nbsp;Thierry Renault ,&nbsp;Sebastien Comas-Cardona","doi":"10.1016/j.jnnfm.2024.105284","DOIUrl":"10.1016/j.jnnfm.2024.105284","url":null,"abstract":"<div><p>This work aims to introduce a groundbreaking approach by directly computing the Fokker–Planck equation, providing a mesoscopic scale orientation indicator based on the 2D-probability density function (PDF) of the fibers’ orientation state. Unlike conventional methods that rely on pre-averaged quantities and closure approximations, our method offers enhanced accuracy and information preservation. The model’s enhanced accuracy can be served as a foundational tool for future studies, enabling the development of comprehensive models describing the fluid-flow coupling problem with precision. Consequently, this advancement facilitates the simulation of real-case scenarios, such as the dynamic motion of fibers during the injection phase of molten thermoplastics within a mold cavity. The novelty of this work lies in its application of the Streamline-Upwind/Petrov–Galerkin (SUPG) finite element method, on both orientation and physical spaces. Our model shows the potential to improve the understanding and prediction of fiber behavior in industrial applications, offering valuable insights into process optimization and design. Implemented within a finite element framework, a comprehensive investigation is conducted into the effects of mesh refinement, time scheme, and time stepping on the computational modeling of the PDF evolution, aiming to strike an optimal balance between model precision and computational efficiency. The validation tests were conducted for the case of simple shear flow to examine the influence of the interaction coefficient <span><math><msub><mrow><mi>C</mi></mrow><mrow><mi>I</mi></mrow></msub></math></span> and the fiber shape factor <span><math><mi>λ</mi></math></span> on the resolution of the probability distribution function. The numerical results demonstrate the evolution of fiber orientation over time under Poiseuille flow conditions.</p></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"331 ","pages":"Article 105284"},"PeriodicalIF":2.7,"publicationDate":"2024-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0377025724001009/pdfft?md5=850e214e156a14bfa4e6229f1726263d&pid=1-s2.0-S0377025724001009-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141689187","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":"Ken Walters: Reflections","authors":"H A Barnes ,&nbsp;I A Frigaard ,&nbsp;G H McKinley ,&nbsp;T N Phillips ,&nbsp;R J Poole ,&nbsp;R I Tanner","doi":"10.1016/j.jnnfm.2024.105285","DOIUrl":"10.1016/j.jnnfm.2024.105285","url":null,"abstract":"<div><p>In this short Editorial to support the Commemorative Special Issue in honour of our founding Editor, Professor Ken Walters FRS, we draw together a series of informal “reflections” from current (and previous) Editors of the Journal, together with a number of his key collaborators.</p></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"331 ","pages":"Article 105285"},"PeriodicalIF":2.7,"publicationDate":"2024-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141708135","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":"Elastically modulated wavy vortex flow","authors":"T. Boulafentis ,&nbsp;T. Lacassagne ,&nbsp;N. Cagney ,&nbsp;S. Balabani","doi":"10.1016/j.jnnfm.2024.105283","DOIUrl":"10.1016/j.jnnfm.2024.105283","url":null,"abstract":"<div><p>We investigate the transition pathway of low elasticity fluids (<span><math><mrow><mi>E</mi><mi>l</mi><mo>=</mo><mn>0.003</mn><mo>−</mo><mn>0.008</mn></mrow></math></span>) in a Taylor-Couette configuration using low-molecular-weight polyacrylamide (PAAM) and visualisation experiments in the Reynolds range from 0 to 300. We report here for the first time an elastically modified wavy vortex flow state with altered spectral and structural characteristics, that precedes the onset of the traditional (inelastic) Newtonian wavy instability. This new wavy regime is characterised by oscillations of both the inflow and outflow boundaries, associated with a weakening of the outflow regions due to low hoop stresses. The modification of the boundaries persists at higher Reynolds numbers, where the spectral characteristics are unaltered compared to the inelastic, Newtonian case. In addition, a hysteretic behaviour is observed for increasing elasticity, as instabilities are shifted towards lower critical Reynolds numbers, confirming the importance of even vanishing elasticity on the stability of Taylor-Couette flows. At higher fluid elasticity (<span><math><mrow><mi>E</mi><mi>l</mi><mo>=</mo><mn>0.06</mn></mrow></math></span>), the amplitude of inflows/outflows oscillations increases, and momentum is transferred axially between adjacent vortices, which may contribute to the emergence of Rotating Standing Waves.</p></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"330 ","pages":"Article 105283"},"PeriodicalIF":2.7,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0377025724000995/pdfft?md5=71d74694e92f73786e7c85ce0d4743af&pid=1-s2.0-S0377025724000995-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141637281","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":"Effects of kinematic hardening of mucus polymers in an airway closure model","authors":"Bartu Fazla ,&nbsp;Oguzhan Erken ,&nbsp;Daulet Izbassarov ,&nbsp;Francesco Romanò ,&nbsp;James B. Grotberg ,&nbsp;Metin Muradoglu","doi":"10.1016/j.jnnfm.2024.105281","DOIUrl":"https://doi.org/10.1016/j.jnnfm.2024.105281","url":null,"abstract":"<div><p>The formation of a liquid plug inside a human airway, known as airway closure, is computationally studied by considering the elastoviscoplastic (EVP) properties of the pulmonary mucus covering the airway walls for a range of liquid film thicknesses and Laplace numbers. The airway is modeled as a rigid tube lined with a single layer of an EVP liquid. The Saramito–Herschel–Bulkley (Saramito-HB) model is coupled with an Isotropic Kinematic Hardening model (Saramito-HB-IKH) to allow energy dissipation at low strain rates. The rheological model is fitted to the experimental data under healthy and cystic fibrosis (CF) conditions. Yielded/unyielded regions and stresses on the airway wall are examined throughout the closure process. Yielding is found to begin near the closure in the Saramito-HB model, whereas it occurs noticeably earlier in the Saramito-HB-IKH model. The kinematic hardening is seen to have a notable effect on the closure time, especially for the CF case, with the effect being more pronounced at low Laplace numbers and initial film thicknesses. Finally, standalone effects of rheological properties on wall stresses are examined considering their physiological values as baseline.</p></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"330 ","pages":"Article 105281"},"PeriodicalIF":2.7,"publicationDate":"2024-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141482008","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":"Drag reduction and degradation of binary polymer solutions","authors":"Peng-fei Shi ,&nbsp;Hai-bao Hu ,&nbsp;Jun Wen ,&nbsp;Luo Xie","doi":"10.1016/j.jnnfm.2024.105279","DOIUrl":"https://doi.org/10.1016/j.jnnfm.2024.105279","url":null,"abstract":"<div><p>Polymer-induced drag reduction has yielded great potential benefits for industrial processes after more than 70 years of research. However, the limitation of low shear stability has hindered further applications. This study investigates the rheology, drag reduction rate (DR), and degradation of binary polymer mixtures comprising a rigid polymer (diutan gum, DG) and a flexible polymer (polyethylene oxide, PEO). The solutions all exhibited shear-thinning behavior, and the mixed solution was less viscous than the pure PEO or DG solutions at the total concentration of 100 ppm. When fixing the PEO concentration at 50 ppm, the mixed solution viscosity significantly increased with the DG concentration. The drag reduction performance of the pure PEO solution, pure DG solution, and various proportions of binary polymer mixtures was analyzed using an in-house rotor device. The DRs of the solutions increased with the Reynolds number (Re), and decreased with shearing time. The binary solution significantly improved the shear stability of the solution without loss of DR compared to the pure PEO solution. The theoretical model for molecular degradation in turbulent flow excellently fitted the experimental data of relative drag reduction with time. Furthermore, the synergistic interaction parameter was calculated, and it was positive for most cases in the mixtures. Additionally, when Re was fixed, the synergistic interaction parameter, related to the composition of binary polymer mixtures, initially decreased and then increased with time.</p></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"330 ","pages":"Article 105279"},"PeriodicalIF":2.7,"publicationDate":"2024-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141486408","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":"Numerical simulation of vortex rings in non-Newtonian fluids","authors":"F. Pimenta ,&nbsp;M.A. Alves ,&nbsp;F.T. Pinho","doi":"10.1016/j.jnnfm.2024.105280","DOIUrl":"10.1016/j.jnnfm.2024.105280","url":null,"abstract":"<div><p>The impulsive viscous flow through an orifice produces vortex rings that self-propagate until total dissipation of the vorticity. This work aims to study numerically such vortex rings for different types of non-Newtonian fluids, including the power-law, Carreau and simplified Phan-Thien-Tanner (PTT) rheological models, with particular focus on the post-formation phase. The simulations were carried out with the finite-volume method, considering small stroke ratios (<em>L</em>/<em>D</em> ≤ 4) and laminar flow conditions (<em>Re</em>_G ≤ 10³), while parametrically varying shear-thinning, inertia and elasticity. The vortex rings generated in power-law fluids revealed some peculiar features compared to Newtonian fluids, such as a faster decay of the total circulation, a reduction of the axial reach and a faster radial expansion. The behavior in Carreau fluids was found to be bounded between that of power-law and Newtonian fluids, with the dimensionless Carreau number controlling the distance to each of these two limits. The vortex rings in PTT fluids showed the most disruptive behavior compared to Newtonian fluids, which resulted from a combined effect between inertia, elasticity and viscous dissipation. Depending on the Reynolds and Deborah numbers, the dye patterns of the vortex rings can either move continuously forward or unwind and invert their trajectory at some point. Elasticity resists the self-induced motion of the vortex rings, lowering the axial reach and creating disperse patterns of vorticity. Overall, this work shows that the particular non-Newtonian rheology of a fluid can modify the vortex ring behavior typically observed in Newtonian fluids, confirming qualitatively some experimental observations.</p></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"330 ","pages":"Article 105280"},"PeriodicalIF":2.7,"publicationDate":"2024-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S037702572400096X/pdfft?md5=032117adbbe5313520e959d0c3eac6ac&pid=1-s2.0-S037702572400096X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141400836","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":"A mesh-free framework for high-order simulations of viscoelastic flows in complex geometries","authors":"J.R.C. King ,&nbsp;S.J. Lind","doi":"10.1016/j.jnnfm.2024.105278","DOIUrl":"https://doi.org/10.1016/j.jnnfm.2024.105278","url":null,"abstract":"<div><p>The accurate and stable simulation of viscoelastic flows remains a significant computational challenge, exacerbated for flows in non-trivial and practical geometries. Here we present a new high-order meshless approach with variable resolution for the solution of viscoelastic flows across a range of Weissenberg numbers. Based on the Local Anisotropic Basis Function Method (LABFM) of King et al. (2020), highly accurate viscoelastic flow solutions are found using Oldroyd B and PPT models for a range of two dimensional problems — including Kolmogorov flow, planar Poiseulle flow, and flow in a representative porous media geometry. Convergence rates up to 9th order are shown. Three treatments for the conformation tensor evolution are investigated for use in this new high-order meshless context (direct integration, Cholesky decomposition, and log-conformation), with log-conformation providing consistently stable solutions across test cases, and direct integration yielding better accuracy for simpler unidirectional flows. The final test considers symmetry breaking in the porous media flow at moderate Weissenberg number, as a precursor to a future study of fully 3D high-fidelity simulations of elastic flow instabilities in complex geometries. The results herein demonstrate the potential of a viscoelastic flow solver that is both high-order (for accuracy) and meshless (for straightforward discretisation of non-trivial geometries including variable resolution). In the near-term, extension of this approach to three dimensional solutions promises to yield important insights into a range of viscoelastic flow problems, and especially the fundamental challenge of understanding elastic instabilities in practical settings.</p></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"330 ","pages":"Article 105278"},"PeriodicalIF":2.7,"publicationDate":"2024-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0377025724000946/pdfft?md5=0fe12ae733559952cd09ad60ef9e20a2&pid=1-s2.0-S0377025724000946-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141482009","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":"Rheology of a suspension of deformable spheres in a weakly viscoelastic fluid","authors":"Liam J. Escott ,&nbsp;Helen J. Wilson","doi":"10.1016/j.jnnfm.2024.105262","DOIUrl":"10.1016/j.jnnfm.2024.105262","url":null,"abstract":"<div><p>In this work, we consider a suspension of weakly deformable solid particles within a weakly viscoelastic fluid. The fluid phase is modelled as a second-order fluid, and particles within the suspended phase are assumed linearly elastic and relatively dilute. We apply a cell model as a proxy for mean field flow, and solve analytically within a cellular fluid layer and its enclosed particle. We use an ensemble averaging process to derive analytical results for the bulk stress in suspension, and evaluate the macroscopic properties in both shear and extensional flow. Our viscometric functions align with existing literature over a surprisingly broad range of fluid and solid elasticities.</p><p>The suspension behaves macroscopically as a second-order fluid, and we give simple formulae by which the reader can calculate the parameters of this effective fluid, for use in more complex simulations. We additionally calculate the particle shape and orientation, and in simple shear flow show that the leading-order modifications to the angle of inclination <span><math><mi>ζ</mi></math></span> act to align the particle towards the flow direction, giving <span><math><mrow><mi>ζ</mi><mo>=</mo><mi>π</mi><mo>/</mo><mn>4</mn><mo>−</mo><mn>3</mn><msub><mrow><mi>C</mi><mspace></mspace><mi>a</mi></mrow><mrow><mi>e</mi></mrow></msub><mo>/</mo><mn>4</mn><mo>+</mo><msub><mrow><mi>α</mi></mrow><mrow><mn>0</mn></mrow></msub><mi>W</mi><mspace></mspace><mi>i</mi><mo>/</mo><mn>2</mn><msub><mrow><mi>α</mi></mrow><mrow><mn>1</mn></mrow></msub></mrow></math></span> where <span><math><msub><mrow><mi>C</mi><mspace></mspace><mi>a</mi></mrow><mrow><mi>e</mi></mrow></msub></math></span> is the elastic capillary number, <span><math><mrow><mi>W</mi><mspace></mspace><mi>i</mi></mrow></math></span> is the Weissenberg number, and <span><math><msub><mrow><mi>α</mi></mrow><mrow><mi>i</mi></mrow></msub></math></span> are material properties of the suspending second-order fluid, for which the ratio <span><math><mrow><msub><mrow><mi>α</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>/</mo><msub><mrow><mi>α</mi></mrow><mrow><mn>1</mn></mrow></msub></mrow></math></span> is negative.</p></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"330 ","pages":"Article 105262"},"PeriodicalIF":2.7,"publicationDate":"2024-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0377025724000788/pdfft?md5=fc0e8bd261134e77275e69416fda66ba&pid=1-s2.0-S0377025724000788-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141409022","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":"Turbulent impingement jet cleaning of thick viscoplastic layers","authors":"H. Hassanzadeh ,&nbsp;D.I. Wilson ,&nbsp;I.A. Frigaard ,&nbsp;S.M. Taghavi","doi":"10.1016/j.jnnfm.2024.105264","DOIUrl":"https://doi.org/10.1016/j.jnnfm.2024.105264","url":null,"abstract":"<div><p>An experimental study is conducted on the use of a normally impinging turbulent water jet (with the Reynolds number of <span><math><mrow><mi>R</mi><mi>e</mi><mo>≈</mo><mn>11</mn><mspace></mspace><mn>800</mn></mrow></math></span>), for cleaning thick layers of a Newtonian fluid and two viscoplastic fluids (<em>i.e.</em>, transparent Carbopol solutions). The layer thickness is larger than the jet radius. Non-intrusive techniques are used to track the geometrical features of the cleaning process in real time. The effects of layer thickness and fluid yield stress on removal behavior, including cleaning radius, cavity radius, and angle, are investigated. A yield stress promotes the initial formation of a blister rather than a cavity, and the rate of removal decreases with increasing layer thickness and yield stress. A relation is presented for the growth of the cavity radius, which fits our experimental observations well. A comparative analysis of submerged and impinging jets reveals, for the first time, the role of air entrainment in the process, with bubble characteristics such as trajectory, size distribution (diameter), and velocity being determined by the yield stress.</p></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"330 ","pages":"Article 105264"},"PeriodicalIF":3.1,"publicationDate":"2024-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0377025724000806/pdfft?md5=decfde8779c5cef63436fc6606e36882&pid=1-s2.0-S0377025724000806-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141308367","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}