Oscillatory Fluid Flow Research Articles

Stokes layers in oscillatory flows of viscoelastic fluids

<h2>Abstract</h2> Oscillatory fluid flows play an important role in industrial problems such as pumping, drilling, and oil recovery, and in physiological processes such as mucous flow in respiration and blood pumping. A key concept in oscillatory flows is the Stokes layer, i.e. the region of fluid adjacent to a wall that is in motion as a result of the wall oscillatory motion along its own plane. In this talk we will discuss oscillatory flows of viscoelastic fluids from the perspective of Stokes viscoelastic layers. We will first revisit Stokes' second problem for a viscoelastic fluid modelled by a single-mode Maxwell constitutive equation, and the generation of viscoelastic shear waves. Next, we will turn the attention to wall-bounded zero-mean oscillatory flows, for which we will identify the governing dimensionless variables and discuss the presence of resonances in the one-dimensional base flow. Finally, we will present experimental evidence of the destabilization of the one-dimensional base flow for a wormlike micellar solution in a cylindrical pipe as the oscillatory forcing increases, and sketch a perturbative analysis based on the Giesekus constitutive equation that links the first instability of the base flow to the divergence of normal radial stresses. If there is enough time, we will also present recent experimental results of oscillatory pipe flow of shear-thinning non-elastic solutions.

Analysis on Cattaneo-Christov heat flux in three-phase oscillatory flow of non-Newtonian fluid through porous zone bounded by hybrid nanofluids

The primary aspect of this study is a theoretical analysis of heat transfer enhancement in the unsteady three-phase oscillatory flow of Casson fluid bounded by the layers of nanofluid and hybrid nanofluids flowing adjacent to the walls of a long-infinite horizontal composite channel. Stoke’s model is employed to define Casson fluid, and one phase model is implemented for nanofluid. Moreover, Cattaneo–Christov heat flux model is also considered. This model amends Fourier’s law of heat transport using thermal relaxation time due to which heat passes through the channel within a finite limit. Analytical solutions are attained through a regular perturbation technique by employing periodic and non-periodic functions and presented through graphical illustrations by implementing the MATHEMATICA program. The outcomes are exhibited with three types of nanomaterials such as copper Cu , copper oxide CuO and copper alumina Cu–Al 2 O 3 with base fluid as water. It is noted that the momentum and heat transport is significant in the case of Casson fluid with porous zone sandwiched between Cu water NFs as compared to Cu–CuO–H 2 O (phase I) and Cu–Al 2 O 3 –H 2 O (phase III) HNFs. Moreover, in the case of injection, it is observed that the effects of Cu nanomaterials are dominant on temperature. On the other side, in suction, the impacts of Cu–Al 2 O 3 nanomaterials are significant on temperature. The results are also compared with a well-known numerical method named as finite element method.

Numeric evaluation from cantilever beam and plate

As soon as fluid passes over a solid surface vortices are formed at the surface of structure to satisfy the no slip boundary conditions at the fluid-structure interface. Vortices that are formed at fluid-structure interface diffuse in fluid domain. In the present study, the strength of vortices is evaluated on the surface of an oscillating structural element (cantilever beam and plate) that is interacting with oscillating fluid flow. In the analysis, the analysis of structural element is carried out by finite element method and analysis of fluid domain is carried out by panel method. It is assumed that the deformed geometry of the structure at any moment is same shape as the vortex sheet. The structure is replaced by a virtual vortex sheet of uniformly distributed point vortices on the surface. A few numerical examples are presented to show the variation of vortex strength, lift and pressure coefficients for different type flow passes over the oscillating rigid and flexible structural element in fluid medium. The strength of vortex depends on fluid flow characteristics around the structural element and motion of structure in fluid medium.

The Oscillatory Flow of Oldroyd-B Fluid with Magnetic Disturbance

The magnetic field intensity will be nondeterminacy with the flow of charged particles thrown out by solar activities, the overlap of adjacent magnetic islands or non-axisymmetric magnetic interference in tokamaks and so on. The model of a generalized Oldroyd-B fluid with fractional derivative under oscillating pressure gradient and magnetic field with some disturbance will be considered in this paper. The disturbance is regarded as the background noise of the system, and the model is described by a fractional stochastic differential equation. Time and space are discretized by L1, L2 schemes based on piecewise linear interpolation and the central difference quotient method. We demonstrate the effects of the amplitude and period of the oscillating pressure gradient, magnetic parameter, fractional parameters and noise on the velocity field, and two special cases are given.

Numerical simulation of entropy transport in the oscillating fluid flow with transpiration and internal fluid heating by GGDQM

The numerical investigation of entropy generation and its depreciation in oscillating fluid flow with internal fluid heating and transpiration is presented. The current examination includes a flow and heat transfer investigation. The flow is driven by an infinite porous plate that is stretched and oscillated periodically in its plane. Boundary layer approximations (BLAs) are used to simplify the momentum and energy equations. A dimensionless nonlinear system of partial differential equations is solved for the velocity field, temperature profile, entropy generation distribution, and Bejan number using the Gear generalized differential quadrature method (GGDQM). The numerical values of skin friction coefficient and dimensionless heat transfer coefficient are tabulated against various flow governing parameters. The applied numerical scheme reliability is established by comparing numerical estimation of the skin friction coefficient and Nusselt number obtained by the GQGM and Gear Gauss-Lobato spectral method (GGLSM). A comparison of numerical data shows an excellent agreement and validates the reliability of the numerical simulation. Tables and graphs demonstrate the effects of various control parameters on the physical quantities of interest. With the rising Eckert number, the thermal and entropy profiles amplify, whereas a decrease in the Bejan number is observed. Furthermore, ininjection and suction instances, entropy and Bejan number profile arguments at and near the oscillating surface.

Electroosmotic pressure-driven oscillatory flow and mass transport of Oldroyd-B fluid under high zeta potential and slippage conditions in microchannels

The appropriate analysis for microscale transport of complex fluids is essential in many scientific and technological devices to establish the accurate theoretical model. For example, the viscoelastic fluid plays a vital role in medical diagnostics to separate biomolecules using the concept of a microchannel flow under time-periodic oscillation effects. The available literature demonstrates no such analysis existed for the time-periodic oscillation of Oldroyd-B fluid subjected to the electroosmotic and slippage flow conditions. The present paper develops a new mathematical approach for an electroosmotic pressure-driven pulsatile-Oldroyd-B fluid flow between two parallel plates in microchannels under slipping actions on the wall surface. The flow takes place in an exponential electric field regime by imposing an exponential pressure gradient with time to simulate the elastic and viscous behaviors of the Oldroyd-B fluid. A finite difference method (MATLAB bvp4c) is employed to solve the strongly non-linear electrical potential and concentration equations. A time-periodic oscillation effect on the velocity profile, concentration distribution, and mass transport is analyzed under low or high zeta potentials at the wall. The results highlight that the elastic nature of fluid increases the oscillatory behavior of flow velocity compared to that of the viscous fluid. The zeta potential (ξ¯)in the flow field is responsible for increasing the flow velocity amplitude. Notably, the flow velocity for a high zeta potential (ξ¯=4) at the wall has increased approximately 142.75% at the peak point compared to the low zeta potential(ξ¯=0.1). The velocity amplitude for a higher elastic fluid (elasticity, E = 0.2) compared to a lower elastic fluid (E = 0.1) amplifies 21.01% at the peak point. Finally, it is noteworthy to demonstrate that for the Oldroyd-B fluid, a resonant behavior of the mass transfer rate is dependent on the combination of the parameters, namely angular Reynolds number and elasticity. In this context, it is evident that the interaction of the fluid elasticity and the oscillatory character of flow enhance the mass transfer rate. This innovative concept can be adapted to amplify the fluid mass transfer rate.

Bubble coalescence and break-up in confined oscillating two-phase flows under microgravity conditions

Passive two-phase heat transfer systems, such as pulsating heat pipes, are a promising thermal management solution for the rapidly growing space sector. The strong coupling between thermal and hydraulic phenomena complicated the development of reliable off-the-shelf components. This was due to the difficulties in establishing and maintaining the desired slug-plug flow pattern in a wider region sufficiently far from the annular flow, which can lead to evaporator dry-out. In this work, inertial effects on the flow pattern are investigated under adiabatic conditions to define what limits the operability range of a device. The fluid motion characteristics of pulsating heat pipes have been mechanically induced to observe conditions that lead to the break-up or coalescence of bubbles. The authors were granted access to the ESA drop tower microgravity platform to explore surface tension dominant flows and higher hydraulic diameters compared to the ground capillary diameters. A range of fluids (FC-72 and ethanol) and diameters (2.5 mm to 8 mm) has been explored, along with combinations of oscillating fluid flow, analysing high-speed images and estimating velocity and acceleration. Both the Reynolds number, in combination with the modified Bond number, have been investigated, plotting the operating points on a flow map, showing a very clear limit between break-up and coalescence when the velocity and acceleration signs are considered. This new conceptual flow map can be used to further improve existing modelling tools for pulsating heat pipes operating under reduced gravity. Furthermore, images demonstrating the break-up and coalescence may be aid to CFD scientists in verifying their results.

Analytical Study on Cattaneo-Christov Heat Flux in Three-Phase Oscillatory Flow of Non-Newtonian Fluid Through Porous Zone Bounded by Hybrid Nanomaterials

Analytical Study on Cattaneo-Christov Heat Flux in Three-Phase Oscillatory Flow of Non-Newtonian Fluid Through Porous Zone Bounded by Hybrid Nanomaterials

Electroosmotic flow of Maxwell fluid in a microchannel of isosceles right triangular cross section

This work is presented to study the unsteady oscillatory electroosmotic flow of Maxwell fluid in a microchannel of an isosceles right triangular cross section. An external time-dependent electric field is applied and high zeta potential conditions are considered. Due to the difficulty of theoretical solution, a numerical method is adopted. The numerical solutions are derived by employing the finite difference method. Finally, the effects of some dimensionless variables, the relaxation time, the angular Reynolds number, the wall zeta potential, and the ratio between the typical length and the Debye length on the velocity profiles, are interpreted graphically.

Oscillatory flow of casson fluid between parallel plates with an inclined magnetic field

The study of heat and mass transfer of oscillatory casson flow inporous medium subject to an inclined magnetic field, radiative heatflux and heat source is presented. It is supposed that Casson fluid islittle conductive and produced emf is insignificant. The solutions ofcoupled partial differential equations of velocity, temperature and con-centration profiles are found using Galerkins technique of finite elementmethod. The effect of various parameters such as Reynolds number Re,Grashoff number Gr, Solute Grashoff number Gc, Peclet number Pe,Hartman number Ha, Scmidth number Sc, Permeability parameter K,Radiative parameter R, Heat generation parameter S, Chemical reactionparameter Kr and frequency parameter w on velocity, temperature andconcentration are shown graphically and skin friction, Nusselts numberand Sherwood number are discussed by tables.

Control of osteoblast arrangement by osteocyte mechanoresponse through prostaglandin E2 signaling under oscillatory fluid flow stimuli

Anisotropic collagen/apatite microstructure is a prominent determinant of bone tissue functionalization; in particular, bone matrix modulates its anisotropic microstructure depending on the surrounding mechanical condition. Although mechanotransduction in bones is governed by osteocyte function, the precise mechanisms linking mechanical stimuli and anisotropic formation of collagen/apatite microstructure are poorly understood. Here we developed a novel anisotropic mechano-coculture system which enables the understanding of the biological mechanisms regulating the oriented bone matrix formation, which is constructed by aligned osteoblasts. The developed model provides bone-mimetic coculture platform that enables simultaneous control of mechanical condition and osteoblast-osteocyte communication with an anisotropic culture scaffold. The engineered coculture device helps in understanding the relationship between osteocyte mechanoresponses and osteoblast arrangement, which is a significant contributor to anisotropic organization of bone tissue. Our study showed that osteocyte responses to oscillatory flow stimuli regulated osteoblast arrangement through soluble molecular interactions. Importantly, we found that prostaglandin E2 is a novel determinant for oriented collagen/apatite organization of bone matrix, through controlling osteoblast arrangement.

Oscillatory Flow of LDL-C and Blood Fluid through a Slanted Channel with Heat within the Sight of Magnetic Field

In this research, we investigated LDL-C and blood movement through a slanted channel with heat within the sight of magnetic field. In the evaluation, mathematical models for the LDL-C and blood stream and energy transfer were developed as partially coupled arrangement of partial differential equation (PDEs), the PDEs were scaled utilizing the dimensionless variables to dimensionless ordinary differential equation, they are further reduced to perturbed differential equations (ODEs) utilizing the perturbation parameters including the oscillatory term, where the non-homogenous equation and conditions are solved straightforwardly utilizing the technique for undetermined coefficient. The velocity and temperature profiles are gotten for certain overseeing boundaries included, and Mathematica codes were created utilizing simulate the impact of entering parameters on the profile. It is seen that the overseeing boundaries impacted that the entering pertinent parameters influences blood flow and it helps it controlling the LDL-C concentration, aiding treatment of atherosclerosis.

Unsteady MHD oscillatory Casson fluid flow past an inclined vertical porous plate in the presence of chemical reaction with heat absorption and Soret effects

AbstractThe purpose of this paper is to perform unsteady hydrodynamic flow over an inclined plate embedded in a porous medium with Soret‐aligned magnetic field and chemical reaction. Once momentum, energy, and mass are equal, they can be combined using the diffusion equation to yield the dimensionless momentum/energy/mass model. Computations were performed to analyze the behavior of fluid velocity, temperature and concentration on the inclined vertical plate with the variation of emerging physical parameters like aligned magnetic field, Casson parameter, inclined angle, chemical reaction including soret parameter. The findings derived from skin friction, Nusselt number, and Sherwood number are included in the tables provided for different parameters. The results match with a special case of previously published work. From the present analysis, it is reported that the presence of angle of inclination, aligned magnetic field, and Casson fluid parameters sustains a retarding effect on velocity. The velocity decreases with increasing angle of inclination, aligned magnetic field parameter, and Casson fluid parameter. Comparisons with previously published work performed and the results are found to be in excellent agreement.

Analytical and numerical study for oscillatory flow of viscoelastic fluid in a tube with isosceles right triangular cross section

Abstract A theoretical investigation is carried out to analyze the oscillatory flow of second-grade fluid under the periodic pressure gradient in a long tube of isosceles right triangular cross section in the present study. The analytical expressions for the velocity profile and phase difference are obtained. The numerical solutions are calculated by using the finite difference method with Crank–Nicolson (C–N) scheme. In comparison with the Newtonian fluid (λ = 0), the effects of retardation time, Deborah number and Womersley number on the velocity profile and phase difference are discussed numerically and graphically. For smaller Womersley number, the behavior of second-grade fluid is dominated by viscosity. For larger Womersley number α = 20, the flow becomes more difficult to be generated under periodic pressure gradient with increasing retardation time. Furthermore, the analytical expressions of the mean velocity amplitude and phase difference are given explicitly for discussing.

Oscillatory Flow and Variable Viscosity by the Heat for the Prandtl -Eyring Fluid through Porous Channel

This paper looked into the effect of heat transfer on the magnetohydrodynamics oscillatory flow of Prandtl-Eyring Fluid through a porous channel. The perturbation procedure is used to obtain accurate forms for velocity profiles. and discuss the solutions for two types of flow “Couette flow and Poiseuille flow” of this problem. The results are presented by graphs. The first section in your paper.

Resonant amplification of enzymatic chemical oscillations by oscillating flow.

Using theory and simulation, we analyzed the resonant amplification of chemical oscillations that occur due to externally imposed oscillatory fluid flows. The chemical reactions are promoted by two enzyme-coated patches located sequentially on the inner surface of a pipe that transports the enclosed chemical solution. In the case of diffusion-limited systems, the period of oscillations in chemical reaction networks is determined by the rate of the chemical transport, which is diffusive in nature and, therefore, can be effectively accelerated by the imposed fluid flows. We first identify the natural frequencies of the chemical oscillations in the unperturbed reaction-diffusion system and, then, use the frequencies as a forcing input to drive the system to resonance. We demonstrate that flow-induced resonance can be used to amplify the amplitude of the chemical oscillations and to synchronize their frequency to the external forcing. In particular, we show that even 10% perturbations in the flow velocities can double the amplitude of the resulting chemical oscillations. Particularly, effective control can be achieved for the two-step chemical reactions where during the first half-period, the fluid flow accelerates the chemical flux toward the second catalytic patch, while during the second half-period, the flow amplifies the flux to the first patch. The results can provide design rules for regulating the dynamics of coupled reaction-diffusion processes and can facilitate the development of chemical reaction networks that act as chemical clocks.

Computational investigation on the response of primary cilia of the cell to the oscillatory fluid flow using fluid-structure interaction method

Primary Cilia is appendage that extrudes from cell surface into the extracellular matrix .These organelles play a sensor role for mechanical stimulation in the cell and due to stretch ion channels in its base, play critical role in induce osteogenic differentiation of stem cells. Primary cilia deflected under fluid flow passing through the surface of the cell, which deflection causes tensile ion channels to be opened. In this study, cilia is assumed as linear elastic. The innovative aspect of this research is exerting of oscillatory fluid flow to the primary cilia and evaluating the response of cilia to the fluid flow. The results show that under conditions of exerting the oscillatory fluid flow, maximum strain occur in the base of the cilia which is experienced by tensile ion channels, is 0.5 and in the condition of steady flow is 0.3, Accordingly, mechanical stimuli are sensed by the tensile ionic channels during oscillatory flow higher than steady flow. osteogenic differentiation of stem cells, in addition, the result showed that by using the oscillatory fluid flow the mechanical stimulation better senses by cilia and It is anticipated that exerting oscillatory fluid flow facilitate osteogenic differentiation of stem cell.

Finite element study of stem cells under fluid flow for mechanoregulation toward osteochondral cells

Investigating the effects of mechanical stimuli on stem cells under in vitro and in vivo conditions is a very important issue to reach better control on cellular responses like growth, proliferation, and differentiation. In this regard, studying the effects of scaffold geometry, steady, and transient fluid flow, as well as influence of different locations of the cells lodged on the scaffold on effective mechanical stimulations of the stem cells are of the main goals of this study. For this purpose, collagen-based scaffolds and implicit surfaces of the pore architecture was used. In this study, computational fluid dynamics and fluid-structure interaction method was used for the computational simulation. The results showed that the scaffold microstructure and the pore architecture had an essential effect on accessibility of the fluid to different portions of the scaffold. This leads to the optimization of shear stress and hydrodynamic pressure in different surfaces of the scaffold for better transportation of oxygen and growth factors as well as for optimized mechanoregulative responses of cell–scaffold interactions. Furthermore, the results indicated that the HP scaffold provides more optimizer surfaces to culture stem cells rather than Gyroid and IWP scaffolds. The results of exerting oscillatory fluid flow into the HP scaffold showed that the whole surface of the HP scaffold expose to the shear stress between 0.1 and 40 mPa and hydrodynamics factors on the scaffold was uniform. The results of this study could be used as an aid for experimentalists to choose optimist fluid flow conditions and suitable situation for cell culture.

Stratification and MHD Effects on Narrow Channel Problems

In this paper we analyze viscous oscillatory MHD inhomogeneous fluid flow through the channel which is narrow and rectangular with one wall being porous through which suction or injection is taken place with constant rate and the other wall being rigid. The equation pertaining to the motion of fluid are simplified by using narrow channel approximation and the simplified equation are solved using similarity transformation and the graphical representation are analyzed for velocity profiles. The results reveal that stratification and MHD effects are found predominantly at the centre of the channel while stratification suppresses the flow in vertical direction. For B 0=0 and N=0 the results are in accordance with that already available in literature.

A Study on Exponential and Linear Density Stratification on Rectangular Channel Problems

In this paper we analyze viscous oscillatory MHD inhomogeneous fluid flow through the rectangular channel with one wall being porous through which suction or injection is taken place with constant rate and the other wall being rigid. The density function in the equation of incompressibility are considered in first case as exponentially distributed and that in the second case as linearly distributed. The governing equation of motion in both cases are solved using similarity transformation and the graphical representation in both cases are analyzed and compared for velocity profiles. Further for second-degree approximation, the exponential stratification reduces to the results of linear stratification results, which are already available in the literature.