Article
Multidisciplinary Sciences
Salah Latreche, Mohamed R. Sari, Mohamed Kezzar, Mohamed R. Eid
Summary: The main aim of this research is to establish an analytical solution for viscoelastic fluids flow obeying the PTT and FENE-P models under fully developed conditions. The study explores the effects of pressure gradient on velocity profile, shear stress, shear rate, and shear viscosity, as well as the effects of pressure gradient and Weissenberg number on normal stress.
ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING
(2021)
Article
Mechanics
M. Mcdermott, T. A. E. Riou, P. R. Resende, M. C. T. Wilson, A. M. Afonso, G. de Boer
Summary: A novel open-source anisotropic k-epsilon-v(2)-f model is proposed for turbulent viscoelastic duct flow with dilute polymeric solutions. The model incorporates polymeric terms into the governing equations of the turbulence model for channel and square duct flow of Newtonian fluids. The performance of the model is validated by simple closure models and direct numerical simulation data, and it demonstrates good capability in capturing drag reduction features under a wide range of rheological parameters.
Article
Chemistry, Multidisciplinary
Arsalan Nikdoost, Pouya Rezai
Summary: This paper investigates the migration and focusing behavior of microparticles in curved microchannels with viscoelastic fluids. The effects of flow velocity, fluid viscoelasticity, and particle size are studied. It is found that the introduction of fluid viscoelasticity enhances microparticle focusing, but the dominance of Dean drag force disrupts focusing at high velocities. The particle behavior is categorized using a non-dimensional analysis. The research findings can contribute to the design of future particle sorting and washing devices.
NEW JOURNAL OF CHEMISTRY
(2023)
Article
Mechanics
Mengqi Zhang
Summary: This study investigates the dynamics of linear non-modal waves in viscoelastic pipe flows of FENE-P fluids using transient growth and resolvent analyses. The research shows that the helical mode experiences greater energy growth than the axisymmetric mode, and when the elastic effect is stronger, the optimal conformation tensor in the pipe centre region becomes greater from a non-modal perspective.
JOURNAL OF NON-NEWTONIAN FLUID MECHANICS
(2021)
Article
Thermodynamics
Kyoungyoun Kim
Summary: This study investigated the reduction of heat transfer in drag-reduced turbulent flows of dilute polymer solutions. The results showed that the turbulent transport of momentum and heat were analogous in drag-reduced flows, similar to Newtonian flows. However, the Colburn analogy was not applicable. The spectral density distribution of the turbulent heat flux was similar to that of the Reynolds shear stress. The study indicated that the flow structures associated with turbulent transport of momentum and heat were approximately identical in drag-reduced and Newtonian flows.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Mechanics
Laison Junio da Silva Furlan, Marcio Teixeira de Mendonca, Matheus Tozo de Araujo, Leandro Franco de Souza
Summary: This work presents a practical methodology to verify the validity of Squire's theorem for viscoelastic fluid flow stability analysis. The validity of the theorem is accessed for different models, showing that it is valid for some isotropic models but not for anisotropic models. This finding is important for understanding the stability of disturbances in fluid flow.
JOURNAL OF NON-NEWTONIAN FLUID MECHANICS
(2022)
Article
Engineering, Chemical
Shihuan Zhang, Mingjun Pang, Zhiying Zheng
Summary: In this study, the behavior of a single bubble in shear-thinning viscoelastic liquids was investigated using a combined Carreau and FENE-CR models based on a volume of fluid method. The effects of Weissenberg number (Wi), polymer stretching parameter (L), Eo & BULL;tvo & BULL;s number (Eo), and rheological index (n) on bubble shape and flow field characteristics were investigated. The results showed that under the influence of elastic stress, the bubble tail became pointed and lengthened along the longitudinal direction with a decrease in Wi. The magnitude of n affected the shape of the bubble, with larger n resulting in an ellipsoidal shape with a cusp and smaller n resulting in a disc shape with the disappearance of the bubble tail tip. Wi influenced the magnitude and range of elastic tensile stress, with an increase in Wi expanding the action range of elastic tensile stress below the bubble tail. The appearance of a negative wake was not directly related to bubble shape but rather to the relaxation of elastic stress.
CHEMICAL ENGINEERING SCIENCE
(2023)
Article
Mechanics
Di Li, Xiangchun Xuan
Summary: This study investigates particle migration in microfluidic manipulation, showing that particles migrate towards the centerline and corners in a viscoelastic flow. The migration is influenced by polymer length.
Article
Mathematics, Applied
Kai Tian, Shujuan An, Zhaodong Ding
Summary: This study investigates the unsteady electro-osmotic flow of fractional viscoelastic fluids in micro-parallel channels, taking into account the velocity slip effect on the walls. An analytical solution is obtained by solving the Cauchy momentum equation, linearized Poisson-Boltzmann equation, and fractional Maxwell constitutive equation. The effects of normalized electrokinetic width K, Deborah number De, slip length L, and fractional derivative alpha on velocity and volume flow rate are discussed. The results show that the dimensionless parameters L, De, and K promote the electro-osmotic flow and resonance behavior of fractional Maxwell fluids, while the microstructure weakens the resonance behavior compared to classical Maxwell fluids.
MATHEMATICAL METHODS IN THE APPLIED SCIENCES
(2023)
Article
Chemistry, Analytical
Jiaxuan Zheng, Jialu Wang, Yongjun Jian
Summary: In this article, the performance of electro-osmotic thrusters filled with non-Newtonian power-law fluids in a microchannel was theoretically investigated. Results show that the performance curves depend strongly on the flow behavior index and the electrokinetic width. It is found that non-Newtonian pseudoplastic fluids are the most suitable propellant solvents in micro electro-osmotic thrusters.
Article
Mechanics
Zhaodong Ding, Yongjun Jian
Summary: The study explores the electrokinetic transports of viscoelastic fluids in various channel geometries and introduces a universal Deborah number to analyze resonances. It is found that the annular geometry is optimal for achieving maximum energy conversion efficiency compared to cylindrical geometry, with a 20% increase in efficiency.
Article
Materials Science, Multidisciplinary
Haifa A. Alyousef, Humaira Yasmin, Rasool Shah, Nehad Ali Shah, Lamiaa S. El-Sherif, Samir A. El-Tantawy
Summary: The fabrication of large osteoarticular implants in vitro is of great interest due to the limited regenerative ability of these tissues. However, growing such cells in vitro is difficult, especially as the extracellular matrix fills the initial porous network. Electro-osmotic pumps are commonly used to achieve proper fluid flow in microfluidic systems. This study analyzed the variations of a two-fluid electro-osmotic flow through a viscoelastic fluid and found that the pumping characteristics were viable using the Ellis model's parameters.
Article
Mathematics, Applied
Stefan Wittschieber, Ajay Rangarajan, Georg May, Marek Behr
Summary: In this study, we explored the application of adaptive meshing techniques for solving viscoelastic flow problems. The results showed that using an anisotropic refinement strategy can reduce the number of mesh elements and produce optimal meshes even in the presence of a singularity in the solution.
COMPUTERS & MATHEMATICS WITH APPLICATIONS
(2023)
Article
Mechanics
Abhilash Reddy Malipeddi, Anik Tarafder, Kausik Sarkar
Summary: The dynamics of a viscoelastic drop suspended in a Newtonian matrix were simulated in two time-periodic extensional flows, an oscillating extensional flow and a rotating extensional flow at finite inertia. The drop deforms alternately in response to the flows, showing similarities despite their different natures. Viscoelasticity has a non-monotonic effect on drop deformation and response, with a resonance response observed due to finite inertia.
JOURNAL OF NON-NEWTONIAN FLUID MECHANICS
(2023)
Article
Mechanics
Yuqi Wei, Yi Chen, Jun Xu, Jie Li
Summary: This study presents a micromixer based on induced charge electro-osmosis with a conductive barrier plate, and investigates the effects of the installation of the conductive plate, the concentration of the polymer, and the shape of the conductive plate on the mixing efficiency. The results demonstrate that the use of a conductive plate significantly improves the mixing efficiency.
Review
Mechanics
M. A. Alves, P. J. Oliveira, F. T. Pinho
Summary: Complex fluids are engineered for specific applications by adding macromolecules to a solvent, imparting viscoelasticity which affects flow instabilities and fluid dynamics. Recent research focuses on numerical methods for simulating viscoelastic fluid flows, particularly the finite-volume method used to assess performance with benchmark flows. Issues in numerical methods and novel applications of viscoelastic fluids requiring further development are also discussed.
ANNUAL REVIEW OF FLUID MECHANICS, VOL 53
(2021)
Article
Thermodynamics
M. McDermott, P. R. Resende, M. C. T. Wilson, A. M. Afonso, D. Harbottle, G. de Boer
Summary: An improved k - omega turbulence model has been developed to predict turbulent flows, with the ability to accurately predict various drag reduction scenarios. The model simplifies predictions of flow features without considering friction velocity dependence.
INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW
(2021)
Article
Polymer Science
Antonio Castelo, Alexandre M. Afonso, Wesley De Souza Bezerra
Summary: Tree-based grids offer the advantages of fast Cartesian discretizations and local mesh refinement, with the main challenge being how to adapt the discretization stencil near interfaces between grid elements of different sizes, usually by utilizing local high-order geometrical interpolations. The implementation of a moving least squares meshless interpolation technique allows for more complex mesh configurations while maintaining overall accuracy, demonstrated through numerical tests and simulations of various fluid flows.
Article
Energy & Fuels
Pedro R. Resende, Leandro C. Morais, Carlos Pinho, Alexandre M. Afonso
Summary: This study numerically investigates microcombustion in an undulate microchannel using premixed hydrogen and air. The results show stable flame structure regardless of the inlet velocity and a reduction in heat flux losses, allowing for the design of simpler systems.
Article
Chemistry, Multidisciplinary
Juliana Bertoco, Rosalia T. Leiva, Luis L. Ferras, Alexandre M. Afonso, Antonio Castelo
Summary: This study presents a numerical investigation on the development length of pressure-driven viscoelastic fluid flow between parallel plates modelled by the gPTT constitutive equation. The results show a non-monotonic behavior of development length with varying model parameters and Weissenberg number. The study also considers the influence of elasticity number.
APPLIED SCIENCES-BASEL
(2021)
Article
Energy & Fuels
Mohsen Ayoobi, Pedro R. Resende, Alexandre M. Afonso
Article
Mechanics
Konstantinos Zografos, Alexandre M. Afonso, Robert J. Poole
Summary: In this paper, the characterisitics of the Adaptive Length Scale Model (ALS-C) in capturing pressure-drop in contraction flows of viscoelastic fluids are investigated. A new method for evaluating the instantaneous change in the adaptive length scale is demonstrated, and a modified approach for the evolution equation of actual extensibility is considered for efficient use in complex numerical simulations. The model parameters can produce behaviors that are found experimentally in viscoelastic fluids and pressure-drop enhancements in flows within 4:1 contractions are achievable.
JOURNAL OF NON-NEWTONIAN FLUID MECHANICS
(2022)
Article
Mechanics
Mateus C. Guimaraes, Fernando T. Pinho, Carlos B. da Silva
Summary: This study employs the FENE-P model to conduct direct numerical simulations and investigate the far-field region of turbulent wakes of viscoelastic fluids. The results show new scaling laws for various parameters and are well supported by the numerical simulations. When the Weissenberg and Deborah numbers are sufficiently large, turbulent viscoelastic wakes exhibit distinctive behavior compared to Newtonian wakes.
JOURNAL OF FLUID MECHANICS
(2022)
Editorial Material
Polymer Science
Celio Fernandes, Salah A. Faroughi, Luis L. Ferras, Alexandre M. Afonso
Article
Chemistry, Physical
P. R. Resende, L. L. Ferras, A. M. Afonso
Summary: The present study numerically investigates stable and pulsatory flame burst in an undulating geometry using premixed hydrogen and air. By considering a linear temperature profile along the wall, the flow dynamics can be analyzed without fixing the flame location. The interaction between the flow dynamics and the combustion reaction provides insights into the physics of more general flows.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2023)
Editorial Material
Chemistry, Multidisciplinary
Luis L. Ferras, Alexandre M. Afonso
APPLIED SCIENCES-BASEL
(2023)
Article
Chemistry, Multidisciplinary
Celio Fernandes, Luis L. Ferras, Alexandre Afonso
Summary: This study evaluates the use of the computational fluid dynamics-discrete element method (CFD-DEM) numerical approach to analyze the behavior of polymer-filled suspensions in a parallel-plate rheometer. The open-source CFD-DEM solver is utilized to model these suspensions under different particle volume fractions and fluid rheologies. The numerical results show good agreement with analytical expressions and experimental measurements, demonstrating a yield stress phenomenon as the particle volume fraction increases.
APPLIED SCIENCES-BASEL
(2023)
Article
Mechanics
Simon J. Haward, Francisco Pimenta, Stylianos Varchanis, Daniel W. Carlson, Kazumi Toda-Peters, Manuel A. Alves, Amy Q. Q. Shen
Summary: Numerical optimization of a six-arm cross-slot device generates three-dimensional fluidic channel shapes that approximate ideal uniaxial (biaxial) stagnation point extensional flow. One of the designed geometries is suitable for microfabrication and achieves optimal flow fields for both Newtonian and viscoelastic fluids. The geometry is called OUBER and is fabricated with high precision by laser-induced etching. Microtomographic-particle image velocimetry measurements confirm accurate imposition of desired flows in a wide region around the stagnation point. In Part II of the paper, pressure drop measurements in the OUBER geometry are used to evaluate extensional rheometry of dilute polymeric solutions compared to planar extension measurements using OSCER.
JOURNAL OF RHEOLOGY
(2023)
Article
Mechanics
Simon J. Haward, Stylianos Varchanis, Gareth H. McKinley, Manuel A. Alves, Amy Q. Shen
Summary: Part I presents a microfluidic device for generating near-homogeneous uniaxial and biaxial elongational flows. In Part II, this device is used to examine the extensional rheology of dilute polymer solutions compared to measurements made under planar extension. The extension rate and tensile stress difference generated in the fluid are measured using micro-particle image velocimetry and excess pressure drop measurements. The results show that at higher polymer concentrations, the experimental measurements deviate from the model predictions due to intermolecular interactions as the polymer chains unravel in the extensional flows.
JOURNAL OF RHEOLOGY
(2023)
Article
Physics, Fluids & Plasmas
German Ferreira, Artur Sucena, Luis L. Ferras, Fernando T. Pinho, Alexandre M. Afonso
Summary: This work presents a detailed numerical investigation on the required development length in laminar Newtonian fluid flow in microchannels with rectangular cross section and different aspect ratios. Accurate estimations of the development length at low Reynolds numbers are important for microsystem design, as inertial forces are less dominant than viscous forces in such flow conditions. A judicious choice of mesh refinement and numerical methods allowed obtaining accurate results and a general correlation for estimating the development length, valid in a wide range of Reynolds numbers and aspect ratios.
Article
Mechanics
Mateus C. Guimaraes, Fernando T. Pinho, Carlos B. da Silva
Summary: A new theory is proposed to describe the conformation state of polymer chains in free turbulent shear flows of viscoelastic fluids. The theory shows the existence of minimum and maximum solvent dissipation reduction asymptotes and four different polymer deformation regimes, based on self-similarity arguments and new scaling relations for the turbulent flux of conformation tensor. In addition, analytical solutions for the self-similar transverse profiles of the conformation tensor components are obtained. The theory is validated through excellent agreement with direct numerical simulations employing the FENE-P rheological model.
JOURNAL OF NON-NEWTONIAN FLUID MECHANICS
(2024)