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Initiation of motion for an isolated finite size particle in a rotating tank flow Fluid Dyn. Res. (IF 1.5) Pub Date : 2024-02-19 Marie Rastello, Jean-Louis Marié, S Karan Venayagamoorthy
The initiation of motion of an isolated finite size particle within a rotating fluid in a tank is investigated experimentally. The study leverages on the absence of slip velocity to explore the impact rotation has on the initiation of the motion of a particle. Results show that the motion, when it occurs, is purely radial. It is initiated when the centrifugal force acting on the particle overcomes
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Roles of chain stretch and concentration gradients in capillary thinning of polymer solutions Fluid Dyn. Res. (IF 1.5) Pub Date : 2024-02-15 Dylan Chase, Michael Cromer
Polymers inhibit the breakup of a liquid filament thinning under surface tension. The coupling of elasticity, capillarity and inertia leads to the well-known beads-on-a-string (BOAS) formation. Additionally, under different conditions, smaller satellite drops can form along the liquid bridge between the main beads. The development of BOAS and satellite drops is controlled by the rheology of the polymer
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Motion characteristics of squirmers in linear shear flow Fluid Dyn. Res. (IF 1.5) Pub Date : 2024-02-13 Geng Guan, Yuxiang Ying, Jianzhong Lin, Jue Zhu
In this study, the two-dimensional lattice Boltzmann method was employed to simulate the motions and distributions of a circular squirmer in a linear shear flow. The objective was to systematically investigate the dynamics of microorganisms or engineered squirmers in a flowing environment. We conducted multiple simulations across a range of self-propelled strengths (0.08 ⩽ α ⩽ 0.8) and squirmer type
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Transient slow motion of a porous sphere Fluid Dyn. Res. (IF 1.5) Pub Date : 2024-02-06 Chan W Yu, Huan J Keh
The start-up creeping motion of a porous spherical particle, which models a permeable polymer coil or floc of nanoparticles, in an incompressible Newtonian fluid generated by the sudden application of a body force is investigated for the first time. The transient Stokes and Brinkman equations governing the fluid velocities outside and inside the porous sphere, respectively, are solved by using the
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Decay of Taylor–Green flow type initial conditions in a two-dimensional domain Fluid Dyn. Res. (IF 1.5) Pub Date : 2024-01-30 Shivakumar Kandre, Dhiraj V Patil
Geophysical flows are often two-dimensional (2D) in nature. The decay dynamics of the canonical, symmetric initial conditions defined by the Taylor–Green (TG) flow is simulated in a 2D domain. The standard lattice Boltzmann equation method with the Bhatnagar–Gross–Krook collision model is employed. The vortex dynamics is investigated for bounded and unbounded flows with various sets of Gaussian vortices
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Direct numerical simulations on oscillating flow past surface-mounted finite-height circular cylinder Fluid Dyn. Res. (IF 1.5) Pub Date : 2024-01-19 Abhishek Kumar, Prashant Kumar, Shaligram Tiwari
In this work, a surface-mounted circular cylinder with a fixed aspect ratio (ratio of height of the cylinder to its diameter) of 5 is subjected to a non-zero mean oscillating flow with a range of frequencies and amplitudes. Three-dimensional direct numerical simulations are then conducted on this finite-height cylinder. The mass and momentum equations are resolved using the finite volume-based Open
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Estimating the pressure force around swimming plankton using micro particle image velocimetry Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-12-12 Fahrettin Gökhan Ergin, Erkan Günaydınoğlu, Dilek Funda Kurtuluş, Navish Wadhwa
Obtaining pressure force for freely swimming microorganisms is a challenging yet important problem. Here, we report the swimming kinematics and dynamics of the zooplankton Acartia tonsa nauplius investigated using Micro Particle Image Velocimetry (µPIV). Using rigid object tracking, we obtain sub-pixel accurate localization of freely swimming A. tonsa, revealing its highly periodic locomotion. We exploit
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Application of singular spectrum analysis to nonstationary time series in flow-induced vibrations of a circular cylinder Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-12-06 Linwei Shen, Qianyun Zhu
In numerical simulations of flow-induced vibrations (FIV) of a circular cylinder, abundant time series data are available, including cylinder displacement and acting forces. Singular spectrum analysis (SSA) is employed to deal with nonstationary multi-component time series produced in two FIV cases with proper interpretation in physics. In the first case, the cylinder displacement time series is decomposed
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Spherical seepage model of Bingham fluid in rough and low-permeability porous media Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-11-30 Shanshan Yang, Ke Zhao, Sheng Zheng
Based on the microstructure of porous media that exhibits statistical self-similarity fractal features, this paper investigates the radial flow characteristics of non-Newtonian fluids within rough porous media. The analytical equation of permeability and starting pressure gradient of Bingham fluid in low permeability rough porous media are established. It is found that the relative roughness is inversely
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Effects of a spherical slip cavity filled with micropolar fluid on a spherical micropolar droplet Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-11-30 Ahmed G Salem
In this work, a two-fluid phase flow problem involving an axisymmetrical quasi-steady motion of a spherical micropolar droplet translating at a concentric point in a second non-mixable micropolar fluid within a spherical impermeable cavity with a slip surface is analysed under low Reynolds numbers. The two fluid phases that have a microstructure (micropolar fluid) are the case that is being focused
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Continuous data assimilation of large eddy simulation by lattice Boltzmann method and local ensemble transform Kalman filter (LBM-LETKF) Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-11-09 Yuta Hasegawa, Naoyuki Onodera, Yuuichi Asahi, Takuya Ina, Toshiyuki Imamura, Yasuhiro Idomura
We investigate the applicability of the data assimilation (DA) to large eddy simulations based on the lattice Boltzmann method (LBM). We carry out the observing system simulation experiment of a two-dimensional (2D) forced isotropic turbulence, and examine the DA accuracy of the nudging and the local ensemble transform Kalman filter (LETKF) with spatially sparse and noisy observation data of flow fields
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Large eddy simulation of thermal stratification effects on tracer gas dispersion in a cavity Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-10-30 W A McMullan, J Mifsud
This paper assesses the effect of thermal stratification on the prediction of inert tracer gas dispersion within a cavity of height (H) 1.0 m, and unity aspect ratio, using large eddy simulation. The Reynolds number of the cavity flow, was 67 000. Thermal stratification was achieved through the heating or cooling of one or more of the walls within the cavity. When compared to an isothermal (neutral)
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Insight into the Eyring–Powell fluid flow model using degenerate operator: geometric perturbation Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-10-25 Saeed ur Rahman, José Luis Díaz Palencia
This work provides a formulation of a fluid flow under a nonlinear diffusion based on a viscosity of Eyring–Powell type along with a degenerate semi-parabolic operator. The introduction of such a degenerate operator is significant as it allows us to explore a further general model not previously considered in the literature. Our aims are hence to provide analytical insights and numerical assessments
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Spanwise phase transition between pure modes A and B in a circular cylinder’s wake. Part II: spatiotemporal evolution of vorticity Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-10-24 L M Lin
Through direct numerical simulation, the transition from pure mode A to mode B in the near wake of a circular cylinder is studied without consideration of vortex dislocations. The Reynolds number Re is calculated from 100 to 330 with a computational spanwise length of 4 diameters. In the present section, the spatiotemporal evolution of the vorticity and its sign are analyzed. The results show that
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Simulation of flow past a squirmer confined in a channel at low Reynolds numbers Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-10-09 Siwen Li, Yuxiang Ying, Deming Nie
The two-dimensional lattice Boltzmann method was employed to numerically investigate the flow around a circular squirmer in a channel at low Reynolds numbers. The study thoroughly examined the impact of various factors on flow structures and drag coefficients (C d) of the squirmer, such as the Reynolds number (Re), self-propelled strength (α), squirmer-type factor (β), blockage ratio (B), and orientation
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Numerical simulation of flow past an 8:1 oscillating rectangular cylinder at Re = 22 000 Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-09-25 Jian Wu, YaKun Liu, Di Zhang, Ze Cao
To investigate the influence of structure’s oscillatory motion on flow, the present study employs the arbitrary Lagrangian–Eulerian method in k–ω shear stress transport (SST) turbulence model to simulate the flow past an oscillating rectangular cylinder at Re= 22 000. The cylinder undergoes reciprocating sinusoidal motion at a specified frequency f e, and the frequency ratio fr (defined as the ratio
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Experimental and numerical study on unsteady entrainment behaviour of ventilated air mass in underwater vehicles Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-09-15 Zhaoyu Qu, Nana Yang, Xiongliang Yao, Wenhua Wu, Guihui Ma
The hydrodynamic characteristics of underwater vehicles are significantly affected by the ventilated cavity covered by the vehicle surface. In this paper, the unsteady flow characteristics of this ventilated cavity are studied using experimental and numerical methods, and the unsteady entrainment behaviour of the ventilated air mass is emphasised. The flow pattern of the ventilated air mass is recorded
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Continuous motion of an electrically actuated water droplet over a PDMS-coated surface Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-09-12 Supriya Upadhyay, K Muralidhar
Electrically actuated linear motion of a water droplet over PDMS-coated single active electrode is analyzed from detailed experiments and modeling. In an experiment, continuous motion of the droplet is achieved when it is located over an active electrode with a horizontal ground wire placed just above in an open-electrowetting-on-dielectric configuration. Using a CCD camera, the instantaneous centroid
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Side plasma flow and stagnation of a conical blunt body vehicle under an axial dipole magnetic field Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-08-25 Chen Wang, Zhenguo Tian, Shengdong Li, Ying Hao
The study of plasma flow under the thermal protection magnetic field of reentry vehicle is helpful to verify the magnetic control thermal protection technology and further understand its flow law. By solving hypersonic magnetohydrodynamics equations and combining with dipole magnetic field conditions, the plasma flow mechanism of radio attenuation measurement (RAM)-CII (RAM Experiment) spacecraft at
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An analytic solution of Navier–Stokes flow past a sphere in the region of intermediate Reynolds number Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-08-04 Yuki Yagi, Kazuki Yabushita, Hiroyoshi Suzuki
We study an analytical solution of steady, laminar, and incompressible flow past a sphere in the region of intermediate Reynolds number. The flow is governed by the Navier–Stokes (N–S) equation and the continuity equation. By applying a simple perturbation method to solve the equations, a second-order approximation cannot be obtained, as well-known (Whitehead’s paradox). Many analytical studies, such
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Spectral link and wave breaking enhanced dissipation of turbulent kinetic energy Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-08-03 Dongrong Zhang
At the ocean surface, the wind shear stress not only drives the ocean currents, but also generates waves and breaks waves. The turbulence in the ocean surface layer (OSL) is much enhanced due to wave breaking. A typical field measurement of this enhanced turbulence is the dissipation of turbulent kinetic energy (TKE) ɛ at a depth y below the ocean surface, which scales as ε∝y−a . However, there is
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Effects of finite depth and surface tension on the linear and weakly non-linear stability of Faraday waves in Hele-Shaw cell Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-07-28 Azeddine Rachik, Saïd Aniss
A linear and a non-linear analysis are carried out for the instability of the free surface of a liquid layer contained in a Hele-Shaw cell subjected to periodic vertical oscillation. The linear stability analysis shows that for certain ranges of the oscillation frequency, the depth of the liquid layer and the surface tension can have a substantial effect on the selection of the wavenumbers and on the
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Rotational vector-based analysis of turbulent structures in channel flow using large eddy simulation simulation Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-07-27 Shen Zhang, Nan Gui, Xingtuan Yang, Jiyuan Tu, Shengyao Jiang
Even with modern measurement techniques and data from direct numerical simulation (DNS), it is very difficult to identify the individual attached eddies and understand their dynamical behavior due to the multi-scale nature of the eddies in wall-bounded flows, which puts these issues at the center of the current debate. However, Liutex vector ( L for short), a rotational vector field with information
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Three-dimensional simulations of fluid flows in oscillating lid-driven cavities using lattice Boltzmann method Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-07-26 Sthavishtha R Bhopalam, D Arumuga Perumal, Ajay Kumar Yadav
We utilize the lattice Boltzmann method to conduct three-dimensional simulations of incompressible flows in oscillating cubic lid-driven cavities. Our investigation focuses on examining the impact of Reynolds number and oscillating frequency on the flow field. Notably, we observe that the flow field can be adequately approximated as two-dimensional within the low and intermediate Reynolds number range
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The linear and non-linear study of effect of rotation and internal heat source/sink on Bénard convection Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-07-14 Sanjalee1*maheshwari15sanjlee@gmail.com, Y D Sharma, O P Yadav
The primary objective of this study is to investigate non-linear Bénard convection in a single-walled carbon nanotube suspension saturated in a rotating porous medium with an internal heat sink/source. The modified Buongiorno model is utilized to formulate the governing equations for the flow. Both linear and weak non-linear stability analyses are conducted in this investigation. The linear stability
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Sedimentation of particles with various shapes and orientations in a closed channel using smoothed particle hydrodynamics Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-07-13 Lizhong Huang, Chun Shao, Ruijin Wang, Jiayou Du, Zefei Zhu
The sedimentation of particles with various shapes and orientations in a closed channel using smoothed particle hydrodynamics is investigated in this paper. The continuity and momentum equations of both fluid and solid are discretized using kernel approximation in the Lagrangian frame. The sedimentation behavior of different general shapes, including circle, pentagon, square, ellipse, rectangle, and
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Exploration of rheological behavior of an Ellis fluid on the onset of thermosolutal porous convection Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-07-13 Y Vinod, I S Shivakumara, K R Raghunatha
The initiation of thermosolutal convective instability is investigated in a horizontal porous layer saturated by a shear-thinning fluid following Ellis’ rheology. The porous layer is heated as well as salted from below and a basic horizontal throughflow prompted by the prescribed pressure gradient is considered. The linear stability analysis is performed using normal mode analysis and the threshold
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Minimal model of quasi-cyclic behaviour in turbulence driven by Taylor–Green forcing Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-07-03 Ryo Araki, Wouter J T Bos, Susumu Goto
We attempt to formulate the simplest possible model mimicking turbulent dynamics, such as quasi-cyclic behaviour (QCB), using only three variables. To this end, we first conduct direct numerical simulations of three-dimensional flow driven by the steady Taylor–Green forcing to find a similarity between a stable periodic orbit (SPO) at a small Reynolds number (Re) and turbulent QCB at higher Re. A close
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Margination of platelet-sized particles in red blood cell suspensions flowing through a Y-shaped confluence microchannel Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-06-29 Akira Noguchi, Yuki Tange, Tomoaki Itano, Masako Sugihara-Seki
In blood flow through microvessels, platelets are known to be distributed in high concentrations near the vessel wall, termed ‘margination’ or ‘near-wall excess’. At the confluence of two vessels, this preferential distribution of platelets is thought to be compromised and reconstituted in the downstream main vessel. The present study aimed to investigate the distance of this margination reconstruction
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The dynamic behavior of a droplet flows through a constricted splitting channel: a lattice Boltzmann study Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-06-20 Dapeng Deng, Huifang Dong, Yusheng Liang
In this paper, a lattice Boltzmann method is used to simulate the dynamic behavior of a droplet flows through a constricted channel, where an obstacle is placed in the center of the constricted channel to split the droplet. The method is first used to simulate the effect of the capillary number Ca on the volume of the divided daughter droplets. Results show that the volume difference between the daughter
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Computationally effective estimation of supersonic flow field around airfoils using sparse convolutional neural network Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-06-01 Ming-Yu Wu, Jiang-Zhou Peng, Zhi-Ming Qiu, Zhi-Hua Chen, Yu-Bai Li, Wei-Tao Wu
This work proposes an innovative approach for supersonic flow field modeling around airfoils based on sparse convolutional neural networks (SCNNs) and Bézier generative adversarial network (GAN), where (1) the SCNN model is built to end-to-end predict supersonic compressible physical flow fields around airfoils from spatially-sparse geometries and (2) the trained Bézier-GAN is utilized to generate
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Small amplitude dust acoustic solitary waves in a magnetized dusty plasma with nonthermal distribution for both electrons and ions Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-05-25 Rasool Barazandeh Kian, Mohammad Hossein Mahdieh
The propagation of dust acoustic solitary waves (DASWs) has been investigated in a magnetized dusty plasma consisting of negatively charged dust particles, nonthermal ions and nonthermal electrons. Using reductive perturbation method, the Korteweg-de-Vries (K-dV) equation is derived. It is found that the basic structures (such as polarity, amplitude, width) of DASWs are influenced by nonthermal ions
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New insights into the extended and generalised PTT constitutive differential equations: weak flows Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-05-09 L L Ferrás, A M Afonso
This work presents a comparison between the PTT-X (extended Phan-Thien and Tanner (PTT)) and the generalised PTT (gPTT) viscoelastic models. The PTT-X model was derived based on a combination of reptation and network theories, allowing in this way a microstructural justification for the kernel function. The gPTT model is based on the network theory, with an empirical kernel function for the rate of
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Phase transition between pure modes A and B in a circular cylinder’s wake. Part I: analysis of fluid forces Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-05-09 L M Lin
Through direct numerical simulations, the transition from pure mode A to mode B in the near wake of a circular cylinder is studied with no effect of vortex dislocations. The Reynolds number is computed from 100 to 330 with the computational spanwise length of 4 diameters. In the present part, fluid forces are analyzed. The results show that mode swapping still exists in the range of Reynolds numbers
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The effect of elevated initial vortex shapes on its evolution Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-04-25 A Elikashvili, E Golbraikh
The formation and evolution of helical vortices in various media is an important hydrodynamic problem. A separate problem is the study of the behavior of the initial vortex, which is elevated above the surface. The evolution of such vortices is a complex multiparameter phenomenon. Based on a simple hydrodynamic model (or minimal model) in Elikashvili et al (2017 Phys. Fluids 29 026602) have been studied
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Numerical analysis of shock characteristics control based on bump Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-03-10 Dawei Li, Kaibo Yu, Xiao Wang, Yuanbo Gao
The effects of bump control on shock aerodynamic characteristics have been investigated by simulations. A bump control that based on the changes of local upper surface of two-dimensional (2D) airfoil or three-dimensional (3D) wing model has been applied to affect the shock intensity and position. The simulation results are close of other experiment when the calculate parameters are same with each other
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Viscous flow through macroscopic spherical cavities in an arbitrary configuration in a granular material Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-03-10 Osamu Sano
Viscous flow through macroscopic spherical cavities in a granular material is theoretically investigated. Number, size and configuration of the cavities are arbitrary, except that cavities are sufficiently distant to allow asymptotic analysis on their interaction, which is taken into account up to O(a/l)3 , where a and l are the characteristic radius and inter-cavity distance, respectively. Dependence
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A full-Eulerian approach for simulation of a system of fluid–rigid–elastic structure interaction based on the vorticity-stream function formulation Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-02-21 Iman Farahbakhsh, Amin Paknejad, Hassan Ghassemi
A monolithic mathematical framework for understanding the fluid–rigid–elastic structure interaction problem is proposed. A numerical method in a secondary formulation of the Navier–Stokes equations accompanying a technique for imposing the rigid boundaries is applied. The one-fluid formulation of the incompressible Navier–Stokes equation, containing the terms governing the elastic structure, is transformed
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Three-dimensional numerical study of acoustic streaming phenomenon in rectangular resonator Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-01-27 Ziemowit Malecha
The article presents a three-dimensional numerical study of the large-amplitude, acoustically driven streaming flow in rectangular resonator for different frequencies of the acoustic wave and different temperature regime, isothermal and 60 K temperature difference between the top and bottom walls. The utilized numerical model was based on the Navier–Stokes compressible equations, the ideal gas model
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Mass transport in oscillatory electroosmotic viscoelectric flow in a hydrophobic microchannel with steric effect Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-01-24 R Baños, J Arcos, O Bautista, F Méndez
We conduct a numerical study of viscoelectric and steric effects on an oscillatory electroosmotic flow (OEOF) and their impact on the mass transport of a passive solute through a hydrophobic microchannel. In many applications of electroosmosis, zeta potentials as high as 100–200 mV can be found; in such a situation, the Debye–Hückel approximation is no longer valid, and the steric effect must be considered
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Numerical simulation of vortex shedding from rectangular cylinders with different elongation ratios Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-01-24 Jian Wu, Yakun Liu, Di Zhang, Ze Cao, Zhuoyue Li
RANS simulations are performed for flow past rectangular cylinders with different elongation ratios (L/D= 1, 2, 4, 6, 8, 10, 12, 14 and 16) at Re= 22 000 using the k-ω SST turbulence model. As L/D increases from 1 to 6, stepwise increase of Strouhal number (St) exists, whereas an almost linear variation of St with respect to L/D can be found (St= 0.1618*L/D) at L/D⩾ 8. In the flow, two small secondary
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Rheology, rheometers, and matching models to experiments Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-01-19 L Ridgway Scott
We consider the general problem of matching rheological models to experiments. We introduce the concept of identifiability of models from a given set of experiments. To illustrate this in detail, we study two rheology models, the grade-two and Oldroyd 3-parameter models, and consider two hypothetical rheometers to see if the coefficients of the rheology models are identifiable from experimental measurements
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A unified model of suspension concentration distribution in sediment mixed turbulent flows using generalized fractional advection-diffusion equation Fluid Dyn. Res. (IF 1.5) Pub Date : 2023-01-03 Snehasis Kundu, Ravi Ranjan Sinha
The fractional operator in a space fractional advection-diffusion equation (FADE) plays a significant role in the mixing and vertical movement of sediment particles in a sediment-laden turbulent flow under non-local effects. Turbulent flow exhibits non-local mixing properties, which leads to the non-Fickian diffusion process that cannot be captured by the traditional diffusion equation. In this work
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The wake of a rectangular flat plate Fluid Dyn. Res. (IF 1.5) Pub Date : 2022-12-28 E Montes Gomez, D Sumner
The mean wake of a three-dimensional surface-mounted rectangular flat plate was studied experimentally in a low-speed wind tunnel for four different aspect (height-to-width) ratios, AR = 3, 2, 1, and 0.5. The Reynolds number based on the plate width was Re = 3.8 × 104 and the boundary layer thickness on the ground plane, relative to the plate width, was δ/W = 1.1. The incidence angle of the plate was
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Numerical study of vortex-induced autorotation of an elliptic blade in lid-driven cavity flow Fluid Dyn. Res. (IF 1.5) Pub Date : 2022-12-22 Ali Akbar Hosseinjani, Ghasem Akbari
Large-scale eddies in a lid-driven cavity are potential sources of angular momentum which can induce rotational effect in a free-to-rotate inertial body due to fluid–structure interaction. The novel objective of the present study is to investigate vortex-induced autorotation of an elliptic blade hinged at the centre of a lid-driven cavity. The governing equations are numerically solved using iterative
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Computational analysis in underexpanded jets simulations Fluid Dyn. Res. (IF 1.5) Pub Date : 2022-12-14 J R Martins, J V Barbosa, F P Santos, L F L R Silva
Flammable gases leaks at high pressures are hazardous, especially the free underexpanded jets. Therefore, understanding their behavior is fundamental to guarantee a safe environment. Due to the difficulty to obtain experimental data from free under expanded jets, related to the great speeds and gradients, computational fluid dynamics (CFD) has become an essential tool. Simulations for free underexpanded
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Finite amplitude electro-thermo convection in a cubic box Fluid Dyn. Res. (IF 1.5) Pub Date : 2022-11-04 Yu-xing Peng, Qiang Liu, Zhong-xian Li, Jian Wu
Three-dimensional electro-thermo-hydrodynamic (ETHD) flows of dielectric fluids driven by simultaneous Coulomb and buoyancy forces in a cubic box is numerically studied. The set of coupled equations associated with the ETHD phenomena are solved with the finite volume method. The code is first validated by comparing the numerically obtained linear critical values of the pure electro-convection and thermal
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The influence of reduced velocity on the control of two-degree-of-freedom vortex induced vibrations of a circular cylinder via synthetic jets Fluid Dyn. Res. (IF 1.5) Pub Date : 2022-11-03 Haibo Wang, Hailong Yu, Yunlan Sun, Rajnish N Sharma
A two-dimensional numerical study is conducted to investigate the influence of the reduced velocity on two-degree-of-freedom vortex induced vibrations of a circular cylinder controlled by synthetic jets ejected in horizontal and vertical directions (β = 0° and β = 90°). The Reynolds number is constant at Re = 150, and the reduced velocity varies in the range of 2.5 and 15 (U* = 2.5–15). The mass ratio
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New numerical methods for calculating statistical equilibria of two-dimensional turbulent flows, strictly based on the Miller–Robert–Sommeria theory Fluid Dyn. Res. (IF 1.5) Pub Date : 2022-10-17 K Ryono, K Ishioka
New numerical methods are proposed for the mixing entropy maximization problem in the context of Miller–Robert–Sommeria’s (MRS) statistical mechanics theory of two-dimensional turbulence, particularly in the case of spherical geometry. Two of the methods are for the canonical problem; the other is for the microcanonical problem. The methods are based on the original MRS theory and thus take into account
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Inertial instability of the time-periodic Kolmogorov flow in a rotating fluid with the full account of the Coriolis force Fluid Dyn. Res. (IF 1.5) Pub Date : 2022-10-13 M V Kurgansky
The inertial parametric instability of a time-dependent spatially periodic flow (Kolmogorov flow) of a rotating stratified Boussinesq fluid is studied, taking fully into account the Coriolis force in the problem and with the possibility that the flow has an arbitrary orientation in the horizontal plane. The existence of instability is shown for velocity shears less than those indicated by the criterion
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Calculation of electro-osmotic flow development length in a rotating three-dimensional microchannel Fluid Dyn. Res. (IF 1.5) Pub Date : 2022-10-05 Manoochehr Barimani, Mehran Khaki Jamei, Morteza Abbasi
The numerical modeling of an electroosmosis flow in a rectangular three-dimensional rotating microchannel has been studied. The study’s goal is to calculate the flow’s development length, and as a novelty, a correlation is proposed to estimate the development length. The flow was simulated for angular velocity (ω) ranges of 0–9 and electric potential (φ) ranges of 0.1–0.3. The results were imported
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Analytic investigation of the compatibility condition and the initial evolution of a smooth velocity field for the Navier–Stokes equation in a channel configuration Fluid Dyn. Res. (IF 1.5) Pub Date : 2022-10-03 Péter Tamás Nagy, Márton Kiss, György Paál
A partial differential equation has usually a regular solution at the initial time if the initial condition is smooth in space, fulfills the governing equations and is compatible with the boundary condition. In the case of the Navier–Stokes equation, the initial velocity field must also be divergence–free. It is common belief that the initial condition is compatible with the boundary condition if the
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Numerical investigation of the information complexity in Lorenz system based on Shannon entropy Fluid Dyn. Res. (IF 1.5) Pub Date : 2022-09-20 Sen Zhang, Tao Jia
To quantify the information embedded in the Lorenz system, the Shannon entropies (also named information entropies) of the convection rate, the horizontal temperature variation, and the vertical temperature variation are calculated under the conditions of different values of the three parameters which are proportional to Prandtl number, Rayleigh number, and the liquid layer dimension respectively.
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Theory of dynamical cavitation threshold for diesel fuel atomization Fluid Dyn. Res. (IF 1.5) Pub Date : 2022-08-01 Toshihide Fujikawa, R Egashira, K Hooman, H Yaguchi, H Masubuchi, S Fujikawa
Theory of dynamical cavitation threshold for vapor and non-condensable gas bubble nuclei is proposed based on a model equation constructed from Rayleigh–Plesset equation for glycerol, the liquid with viscosity higher than that of water by 1500 times, under a finite duration of strong tension. The model equation is ascertained to be valid in cases of strong tension under which cavitation occurs. Our
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Effects of feeding pressures on the flowfield structures of three-dimensional film cooling Fluid Dyn. Res. (IF 1.5) Pub Date : 2022-07-28 Xinhai Zhao, Shihe Yi, Qi Mi, Haolin Ding, Lin He
A Mach 2.6 annular supersonic nozzle was designed to protect a hypersonic cone. The annular nozzle is able produce tangential cooling film around the cone. Experiments were carried out in a hypersonic wind tunnel under different cooling film feeding pressures and different attack angles. Temperature-sensitive paint (TSP) was used to measure surface temperature of the cone body; schlieren method was
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Energy stability of thermally modulated inclined fluid layer Fluid Dyn. Res. (IF 1.5) Pub Date : 2022-07-25 Manisha Arora, Renu Bajaj
The stability of natural convection in thermally modulated inclined fluid layer is analyzed using linear instability analysis and generalized energy stability theory. A sufficient condition for the global stability of the fluid layer is obtained. The stability boundaries are found in terms of the Rayleigh number. Shooting method is used to find the stability limits numerically. Uncertain stability
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Using spectral geometry to predict pressure losses in curved pipes at high Reynolds numbers Fluid Dyn. Res. (IF 1.5) Pub Date : 2022-07-08 Alexander Baron
The object of this paper is to apply spectral geometry methods to predicting pressure losses in mildly curved pipes at high Reynolds numbers. The obtained formula for the pressure losses is theoretically justified and provides good agreement with the experimental results.
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Theoretical drag analyses of laminar channel and pipe flows with wall roughness Fluid Dyn. Res. (IF 1.5) Pub Date : 2022-07-08 Tongbiao Guo, Shan Zhong, David Apsley, Tim Craft
In this paper, an exact expression for the drag coefficient of a streamwise-periodic steady incompressible laminar channel and pipe flow with micro- or macro-scale wall roughness is derived, whereby the drag coefficient is decomposed into contributions from different components of the velocity gradient tensor in the flow field. It is shown through our theoretical analysis that drag reduction cannot
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Initially generated pure mode A in the three-dimensional wake transition of a circular cylinder Fluid Dyn. Res. (IF 1.5) Pub Date : 2022-06-29 L M Lin
The initially generated pure mode A, as a transitional stage, is investigated in the three-dimensional wake transition of a circular cylinder. Direct numerical simulations are carried out over a range of Reynolds numbers from 100 to 210. According to the different dynamic behaviors of hydrodynamic parameters and similar features in the spatiotemporal evolution of vorticity in the near wake, two stages
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Aeroacoustic source prediction using material surfaces bounding the flow Fluid Dyn. Res. (IF 1.5) Pub Date : 2022-06-22 M J McPhail, M H Krane
This article presents an extension of Liepmann’s characterization of an aeroacoustic source in terms of the motion of a bounding surface containing the source region. Rather than using an arbitrary surface, we express the problem in terms of bounding material surfaces, identified by Lagrangian coherent structures (LCSs), which demarcate flow into regions with distinct dynamics. The sound generation