Journal of Non-Newtonian Fluid Mechanics最新文献

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Rheology of a suspension of deformable spheres in a weakly viscoelastic fluid 弱粘弹性流体中可变形球体悬浮液的流变学
IF 2.7 2区 工程技术
Journal of Non-Newtonian Fluid Mechanics Pub Date : 2024-06-09 DOI: 10.1016/j.jnnfm.2024.105262
Liam J. Escott , Helen J. Wilson
{"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}
引用次数: 0
Turbulent impingement jet cleaning of thick viscoplastic layers 厚粘塑性层的湍流撞击射流清洗
IF 3.1 2区 工程技术
Journal of Non-Newtonian Fluid Mechanics Pub Date : 2024-06-05 DOI: 10.1016/j.jnnfm.2024.105264
H. Hassanzadeh , D.I. Wilson , I.A. Frigaard , S.M. Taghavi
{"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}
引用次数: 0
Optimizing die profiles using a hybrid optimization algorithm for the precise control of extrudate swell in polymer solutions 使用混合优化算法优化模具轮廓,精确控制聚合物溶液中的挤出膨胀
IF 3.1 2区 工程技术
Journal of Non-Newtonian Fluid Mechanics Pub Date : 2024-06-04 DOI: 10.1016/j.jnnfm.2024.105277
Alireza Maddah, Azadeh Jafari
{"title":"Optimizing die profiles using a hybrid optimization algorithm for the precise control of extrudate swell in polymer solutions","authors":"Alireza Maddah,&nbsp;Azadeh Jafari","doi":"10.1016/j.jnnfm.2024.105277","DOIUrl":"https://doi.org/10.1016/j.jnnfm.2024.105277","url":null,"abstract":"<div><p>In recent years, many researchers have focused on improving the die design process for polymer extrusion. This study proposes the development of an efficient and robust numerical approach to improve the die-designing process of polymer melts using the Giesekus model. The proposed technique uses a hybrid optimization algorithm to systematically minimize an objective function to achieve the desired extrudate shape. First, we examine the proposed objective function for the 2D axisymmetric test case using the Golden Section optimization algorithm to obtain a circular extrudate of high-density polyethylene (HDPE) with the desired radius at moderate Weissenberg numbers from 1 to 3.75. To provide more insights into the viscoelastic nature of the problem, the optimization was repeated for a viscoelastic fluid with a higher viscosity ratio and a lower mobility factor at very high Weissenberg numbers, specifically 45, 60, 75, and 90. The proposed approach performs quite well across a broad range of Weissenberg numbers. Subsequently, a hybrid optimization algorithm that combines Nelder-Mead and Bayesian optimization algorithms is employed to achieve the desired extrudate shape for various extrudate profiles in 3D cases, including rectangular and square cross-sections, at a Weissenberg number of one. To gain additional insights into the viscoelastic nature of the problem, optimization was conducted for the rectangular extrudate with a 2:1 aspect ratio at higher Weissenberg numbers, i.e. Weissenberg number from 1 to 2.6. The results of the three-dimensional case studies indicate that both the Nelder-Mead and Bayesian optimization algorithms are efficient and robust, converging relatively quickly in all cases studied. The Nelder-Mead algorithm appears to be more robust, exhibiting fewer oscillations when reaching the optimum point. On the other hand, the Bayesian optimization algorithm can reach the global optimum point at a computational cost comparable to Nelder-Mead, while achieving greater accuracy. In conclusion, these findings indicates that using this hybrid optimization algorithm in the polymer extrusion die-designing process can provide a high level of efficiency and robustness.</p></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"330 ","pages":"Article 105277"},"PeriodicalIF":3.1,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141308366","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}
引用次数: 0
ViscoelasticNet: A physics informed neural network framework for stress discovery and model selection ViscoelasticNet:用于应力发现和模型选择的物理信息神经网络框架
IF 3.1 2区 工程技术
Journal of Non-Newtonian Fluid Mechanics Pub Date : 2024-06-04 DOI: 10.1016/j.jnnfm.2024.105265
Sukirt Thakur , Maziar Raissi , Arezoo M. Ardekani
{"title":"ViscoelasticNet: A physics informed neural network framework for stress discovery and model selection","authors":"Sukirt Thakur ,&nbsp;Maziar Raissi ,&nbsp;Arezoo M. Ardekani","doi":"10.1016/j.jnnfm.2024.105265","DOIUrl":"https://doi.org/10.1016/j.jnnfm.2024.105265","url":null,"abstract":"<div><p>Viscoelastic fluids are a class of fluids that exhibit both viscous and elastic nature. Modeling such fluids requires constitutive equations for the stress, and choosing the most appropriate constitutive relationship can be difficult. We present viscoelasticNet, a physics-informed deep learning framework that uses the velocity flow field to select the constitutive model and learn the stress field. Our framework requires data only for the velocity field, initial &amp; boundary conditions for the stress tensor, and the boundary condition for the pressure field. Using this information, we learn the model parameters, the pressure field, and the stress tensor. This work considers three commonly used non-linear viscoelastic models: Oldroyd-B, Giesekus, and linear Phan-Tien-Tanner. We demonstrate that our framework works well with noisy and sparse data. Our framework can be combined with velocity fields acquired from experimental techniques like particle image velocimetry to get the pressure &amp; stress fields and model parameters for the constitutive equation. Once the model has been discovered using viscoelasticNet, the fluid can be simulated and modeled for further applications.</p></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"330 ","pages":"Article 105265"},"PeriodicalIF":3.1,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141424136","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}
引用次数: 0
Viscoelastic flows of a lid-driven cavity using spectral element methods 利用谱元法研究顶盖驱动空腔的粘弹性流动
IF 2.7 2区 工程技术
Journal of Non-Newtonian Fluid Mechanics Pub Date : 2024-05-31 DOI: 10.1016/j.jnnfm.2024.105263
D. Fenton , P.J. Bowen , E. De Angelis
{"title":"Viscoelastic flows of a lid-driven cavity using spectral element methods","authors":"D. Fenton ,&nbsp;P.J. Bowen ,&nbsp;E. De Angelis","doi":"10.1016/j.jnnfm.2024.105263","DOIUrl":"10.1016/j.jnnfm.2024.105263","url":null,"abstract":"<div><p>The performance of a spectral element method in the DEVSS-G formulation for the solution of non-Newtonian flows is assessed by means of a systematic analysis of the benchmark lid-driven cavity problem. It is first validated by comparison with the creeping Newtonian and Oldroyd-B flows, where in the latter case a lid velocity regularisation scheme must be employed to remove the singularity at the lid-wall interfaces. In both instances, excellent agreement is found with the literature for stable, time-independent flows, and in fact it is shown that higher Weissenberg numbers can be obtained using the present methodology for these types of flow. Some physical aspects of the solutions are also presented and discussed, however at increasing Weissenberg numbers, the methodology breaks down due to a lack of convergence in the BDF/FPI time advancement scheme. By systematically assessing the effects of the levels of <span><math><mrow><mi>h</mi><mi>p</mi></mrow></math></span>-refinement and temporal refinement on the flow fields, as well as the introduction of the extension-limiting Giesekus mobility parameter in the constitutive equations, it is demonstrated that in each instance the inability to accurately resolve the stress gradients leads to a compounding of errors in the BDF/FPI regime, ultimately causing it to diverge.</p></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"330 ","pages":"Article 105263"},"PeriodicalIF":2.7,"publicationDate":"2024-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S037702572400079X/pdfft?md5=f8142b7a8fdfcede95f12c74faddc167&pid=1-s2.0-S037702572400079X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141512995","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}
引用次数: 0
Long-wave instabilities of a power-law fluid flowing over a heated, uneven and porous incline: A two-sided model 幂律流体在受热、不均匀和多孔斜面上流动时的长波不稳定性:双面模型
IF 3.1 2区 工程技术
Journal of Non-Newtonian Fluid Mechanics Pub Date : 2024-05-18 DOI: 10.1016/j.jnnfm.2024.105260
Jean Paul Pascal , Andrea Vacca
{"title":"Long-wave instabilities of a power-law fluid flowing over a heated, uneven and porous incline: A two-sided model","authors":"Jean Paul Pascal ,&nbsp;Andrea Vacca","doi":"10.1016/j.jnnfm.2024.105260","DOIUrl":"https://doi.org/10.1016/j.jnnfm.2024.105260","url":null,"abstract":"<div><p>The stability conditions of a two-dimensional gravity-driven flow of a thin layer of a power-law fluid flowing over a heated, uneven, inclined porous surface are investigated. A two-sided model is employed to account for the bottom filtration in the porous layer. The governing equations are reduced under the long-wave approximation and the cross-stream dependence is eliminated by means of the Integral Boundary Layer technique. Floquet–Bloch theory is used to investigate at linear level how the porous bottom waviness influences the thermocapillarity stability of the flow in a shear-thinning fluid. Differently from the even case, the linear stability analysis suggests that for flow over sufficiently wavy undulations the thermocapillarity may stabilize the equilibrium flow, depending on the values of dimensionless governing numbers and parameters. This stabilizing phenomenon is enhanced by the shear-thinning rheology of the fluid while it is reduced by the permeability of the layer. Numerical simulations, performed solving the reduced nonlinear model through a second order Finite Volume scheme, confirm the results of the linear stability analysis.</p></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"329 ","pages":"Article 105260"},"PeriodicalIF":3.1,"publicationDate":"2024-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141097574","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}
引用次数: 0
Numerical investigation of drop–film interactions with a thixotropic liquid 滴膜与触变性液体相互作用的数值研究
IF 3.1 2区 工程技术
Journal of Non-Newtonian Fluid Mechanics Pub Date : 2024-05-17 DOI: 10.1016/j.jnnfm.2024.105259
Jonas Steigerwald, Matthias Ibach, Anne K. Geppert, Bernhard Weigand
{"title":"Numerical investigation of drop–film interactions with a thixotropic liquid","authors":"Jonas Steigerwald,&nbsp;Matthias Ibach,&nbsp;Anne K. Geppert,&nbsp;Bernhard Weigand","doi":"10.1016/j.jnnfm.2024.105259","DOIUrl":"10.1016/j.jnnfm.2024.105259","url":null,"abstract":"<div><p>We investigate numerically the influence of thixotropic effects on the impact of a drop onto a thin film, a fundamental process in many technical systems. Direct numerical simulations are performed with a Volume-of-Fluid (VOF) method based multiphase flow solver whose capabilities are expanded in order to enable simulations of a thixotropic liquid. The thixotropic behavior is modeled by a rate kinetic equation for the structural integrity of the assumed microstructure of the liquid. The corresponding structural parameter is described by an additional VOF-variable. After a validation of the implementations, we vary systematically the two parameters of the thixotropic model for a selected impact scenario in order to identify thixotropic effects during the impact and on the overall impact morphology. The two parameters are the mutation number <span><math><mrow><mi>M</mi><mi>u</mi><mo>=</mo><msub><mrow><mi>t</mi></mrow><mrow><mtext>exp</mtext></mrow></msub><mo>/</mo><msub><mrow><mi>t</mi></mrow><mrow><mi>θ</mi></mrow></msub></mrow></math></span> as the ratio of the experimental time scale to the time scale of the structural rebuilding and the parameter <span><math><mi>β</mi></math></span>, which describes the effectivity of the shear-induced structural disintegration. The parameter study leads to a regime map with three different regimes. For <span><math><mrow><mi>M</mi><mi>u</mi><mo>&gt;</mo><mn>10</mn></mrow></math></span>, the liquid behaves purely shear-thinning. High shear rates during the early stages of the impact lead to a low apparent viscosity at the crown base and to an enhanced crown growth. For <span><math><mrow><mi>M</mi><mi>u</mi><mo>&lt;</mo><mn>0</mn><mo>.</mo><mn>1</mn></mrow></math></span>, the liquid behaves irreversible thixotropic or rheodestructing, respectively. Structural rebuilding is negligible and every deformation leads to a further disintegration of the microstructure. In this regime, a thin region of disintegrated microstructure develops within the liquid, spanning from the location of high shear stresses at the bottom into the crown rim. In between these two regimes, purely thixotropic effects become significant. A complex microstructure develops during the impact, in which features of both regimes occur combined, leading to a pronounced viscosity gradient along the crown wall. A comparison of the resulting maximum crown heights reveals that various combinations of <span><math><mrow><mi>M</mi><mi>u</mi></mrow></math></span> and <span><math><mi>β</mi></math></span> values can lead to the same maximum crown height whereas the crown shapes prior to this point in time can be very different.</p></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"329 ","pages":"Article 105259"},"PeriodicalIF":3.1,"publicationDate":"2024-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0377025724000752/pdfft?md5=e67e8f3a6c5042fce5bfff6de47c67ce&pid=1-s2.0-S0377025724000752-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141058163","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}
引用次数: 0
On the use of sinusoidal vibrations for disaggregating clusters of non-settling inertial particles immersed in yield-stress fluids 利用正弦振动分解浸入屈服应力流体中的非沉降惯性微粒团块
IF 3.1 2区 工程技术
Journal of Non-Newtonian Fluid Mechanics Pub Date : 2024-05-17 DOI: 10.1016/j.jnnfm.2024.105261
N.P. Khabazi , T. Rezaee , M. Pourjafar-Chelikdani , S.M. Taghavi , K. Sadeghy
{"title":"On the use of sinusoidal vibrations for disaggregating clusters of non-settling inertial particles immersed in yield-stress fluids","authors":"N.P. Khabazi ,&nbsp;T. Rezaee ,&nbsp;M. Pourjafar-Chelikdani ,&nbsp;S.M. Taghavi ,&nbsp;K. Sadeghy","doi":"10.1016/j.jnnfm.2024.105261","DOIUrl":"10.1016/j.jnnfm.2024.105261","url":null,"abstract":"<div><p>The effect of sinusoidal vibration is numerically investigated on the dynamical behavior of a cluster of 50 identical non-Brownian circular solid particles randomly distributed in a circular envelope. The cluster is immersed in a finite vessel filled with an inelastic viscoplastic fluid obeying the Casson model. The solid particles are modeled using the improved smoothed-profile method (iSPM) whereas the flow of the continuous phase is modeled using the lattice Boltzmann method (LBM). An in-house LBM-iSPM code, modified for Casson fluid, is used to study the effect of sinusoidal vibration on disaggregating the cluster. We have deliberately ignored the gravitational term in the equations of motion so that the sole effect of vibration on the cluster response can better be investigated. Numerical results suggest that vibration can disaggregate the cluster with its efficiency depending on the fluid's yield stress. For any given yield stress, vibration can disperse the cluster provided the frequency and/or amplitude of the forced oscillation are larger than a threshold. The secondary flow formed in the channel during the transient phase is shown to be the main cause of the cluster's fluid-mediated dispersion. It is shown that the system reaches equilibrium when the secondary flow is vanished through dissipation. Vibration is predicted to become more effective in disaggregating clusters the larger the size of the particles or the smaller their number density.</p></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"329 ","pages":"Article 105261"},"PeriodicalIF":3.1,"publicationDate":"2024-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141038631","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}
引用次数: 0
Drag reduction assisted emulsification in a micro-channel 微通道中的减阻辅助乳化技术
IF 3.1 2区 工程技术
Journal of Non-Newtonian Fluid Mechanics Pub Date : 2024-05-14 DOI: 10.1016/j.jnnfm.2024.105247
Elia Missi , Agnès Montillet , Jérôme Bellettre , Teodor Burghelea
{"title":"Drag reduction assisted emulsification in a micro-channel","authors":"Elia Missi ,&nbsp;Agnès Montillet ,&nbsp;Jérôme Bellettre ,&nbsp;Teodor Burghelea","doi":"10.1016/j.jnnfm.2024.105247","DOIUrl":"10.1016/j.jnnfm.2024.105247","url":null,"abstract":"<div><p>An experimental study of the turbulent dynamics of emulsification in a cross-slot microfluidic device is presented. The continuous phase contains a minute amount of an inelastic polymer (xanthan). The Reynolds numbers are sufficiently large (up to 16000) so the drag reduction phenomenon is observed during the emulsification process. The statistics of droplet sizes in the resulting emulsions are measured ex-situ by means of digital microscopy in a wide range of Reynolds numbers and polymer concentrations in the continuous phase. Integral measurements of the statistics of the pressure drops in the micro-channel allow one to systematically map the drag reduction states. Corresponding to each state, the space–time dynamics of the emulsification process are assessed by means of in-situ high speed imaging of the interface between the two fluids which further allows one to extract the characteristic time and space scales associated to the dynamics of the interface. Various dynamic regimes of the microscopic emulsification process are mapped in terms of the Reynolds number and shear thinning rheology of the continuous phase.</p></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"329 ","pages":"Article 105247"},"PeriodicalIF":3.1,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141027679","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}
引用次数: 0
The rheological kolmogorov scales of viscoelastic Oldroyd-B fluids 粘弹性奥尔德罗伊德-B 流体的流变科尔莫戈罗夫尺度
IF 3.1 2区 工程技术
Journal of Non-Newtonian Fluid Mechanics Pub Date : 2024-05-11 DOI: 10.1016/j.jnnfm.2024.105257
H.R. Anbarlooei , F. Ramos , G.E.O. Celis , C. Mageski , D.O.A. Cruz
{"title":"The rheological kolmogorov scales of viscoelastic Oldroyd-B fluids","authors":"H.R. Anbarlooei ,&nbsp;F. Ramos ,&nbsp;G.E.O. Celis ,&nbsp;C. Mageski ,&nbsp;D.O.A. Cruz","doi":"10.1016/j.jnnfm.2024.105257","DOIUrl":"10.1016/j.jnnfm.2024.105257","url":null,"abstract":"<div><p>This article introduces a method to determine the Kolmogorov rheological scales for turbulent flow in Viscoelastic Oldroyd-B fluids. The findings reveal a noteworthy characteristic wherein the Kolmogorov rheological length is consistently smaller than that observed in Newtonian cases. Moreover, this length diminishes with an increase in the prominence of elastic effects. Leveraging these rheological scales, a detailed friction equation for turbulent flow in Oldroyd-B fluids is derived. The resultant friction relationship exhibits a high degree of agreement with existing theories. Notably, it delineates the Maximum Drag Reduction (MDR) scenario for the studied case (<span><math><mi>β</mi></math></span>=0.9). Additionally, the investigation delves into the onset of drag reduction effects, shedding light on the transitional phases in viscoelastic fluid flows.</p></div>","PeriodicalId":54782,"journal":{"name":"Journal of Non-Newtonian Fluid Mechanics","volume":"329 ","pages":"Article 105257"},"PeriodicalIF":3.1,"publicationDate":"2024-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141034035","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}
引用次数: 0
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