Unsteady flow of viscoelastic fluid with the fractional K-BKZ model between two parallel plates

In the present paper, we investigate the unsteady flow of a viscoelastic fluid between two parallel plates which is generated by the impulsively accelerated motion of the bottom plate. Based on the result of (Jaishankar and McKinley, 2014), the fractional K-BKZ constitutive equation is obtained from the fractional Maxwell model. Using respectively the fractional Maxwell model and fractional K-BKZ model, the unidirectional flows between two plates are simulated and compared. The velocity field and shear stress of the flows are calculated by developing efficient finite difference schemes. The results show that the fluid with the fractional Maxwell model gradually loses the viscoelasticity, but the fluid with the fractional K-BKZ model continues to preserve the viscoelasticity. The dependence of the flow velocity on various parameters of the fractional K-BKZ model is analyzed graphically.     

Unsteady flow of fluids with microstructure between parallel plates—II

Two types of unsteady flow between two parallel plates of a fluid with microstructure have been considered. (i) Initially the fluid is at rest and the motion is caused by a sudden change of pressure gradient from zero to a constant value. It is shown that for a given time asα* decreases from infinity to zero, the velocity in the flow decreases. (ii) One plate is fixed and the other is accelerated with a velocity ν = Ut ⁿ (U andn being positive constants). The flow pattern is discussed in both cases in detail.     

Unsteady couette flow of a conducting fluid between two parallel plates under a transverse magnetic field—II

The effect of a sudden change in magnetic field and pressure gradient on a steady Couette flow of a viscous incompressible fluid between two parallel plates in the presence of a transverse magnetic field is considered. Expressions for the velocity of the fluid in the disturbed flow, the intensities of the electrical and magnetic fields are obtained in two cases when the plates are non-conducting and when they are perfectly conducting.     

Unsteady couette flow of a conducting fluid between two parallel plates under a transverse magnetic field—I

The unsteady Couette flow of a viscous incompressible fluid between two parallel plates in the presence of a transverse magnetic field is considered. Using the Laplace transform technique, expressions for the velocity of the fluid and the intensities of the electrical and magnetic fields are obtained in two cases; when the plates are non-conducting and when they are perfectly conducting.     

On the hydromagnetic flow between two parallel,porous plates

This paper deals with the two-dimensional unsteady flow of a conducting viscous incompressible fluid between two parallel, porous plates, one of which is fixed, while the other is uniformly accelerated, when there is a transverse magnetic field. It is shown that, for a given Hartmann number M, as suction parameter β increases, the velocity at any point of the fluid increases, the Skin friction at the stationary plate increases, while that at the accelerated plate decreases. The results are true, as time T increases, for given Hartmann number M and the suction parameter β. The results also hold good for a given β, as M increases when the magnetic lines of force are fixed relative to the plate, while they are just opposite for the magnetic lines of force fixed relative to the fluid.     

Generalized couette flow of a dipolar fluid between two parallel plates

Résumé Dans ce travail, on présente une solution du problème de l'écoulement d'un fluide dipolaire entre deux plaques parallèles, dont l'une est en mouvement et l'autre fixe, en présence d'un gradient de pression. On trouve qu'il n'y a pas d'effet dipolaire sur l'écoulement si le gradient de pression n'est pas appliqué, et que pour un fluide dipolaire avec =0, étant le rapport entre l'espace des deux plaques et la constante dipolaire du fluide, le profil de vitesse n'est pas affecté par le gradient de pression.     

Linearized Poiseuille flow between parallel plates

Zusammenfassung Der Gasstrom eines verdünnten Gases zwischen zwei unendlichen, parallelen Platten (ebene Poiseuille-Strömung) wird berechnet. Die vollständige, linearisierte Boltzmann-Gleichung wird mittels Variationsverfahren behandelt. Die Näherungsfunktion entspricht in Kontinuumsnähe der exakten Burnettverteilung, Resultate werden für das Modell starrer Kugeln und für Maxwellmoleküle angegeben.

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On leave, 1969–1970, from the University of Missouri, Columbia, Missouri, USA.     

Dusty effects on pulsating viscous flow of two immiscible fluids between two parallel plates

The flow of two immiscible incompressible dusty viscous fluids between two parallel plates generated by a pulsating pressure gradient is investigated. Velocity fields for the fluid-particle system along with the expressions for the skin friction drag at the plates are obtained and studied graphically. It is found that there is an immediate response to pressure fluctuations in the first stream at low frequency range 0<σ≤4 being maximum at σ=4. On the contrary, the second stream is more responsive to fluctuations at relatively higher frequencies. The maximum response in this case is shifted to σ=16.     

Oscillatory flow of dipolar fluids between parallel plates

The oscillatory flow of an incompressible dipolar fluid under isothermal conditions between parallel plates is studied. It is found that the velocity field is governed by two parameters characterising the fluid; and that for small frequencies the velocity is in phase with the exciting pressure gradient and the effect of dipolar inertia terms is negligible. For large frequencies, the flow has a boundary layer character and it is affected by both the parameters. Outside the layer there is a core about the axis in which the flow is affected only by the dipolar inertia terms.     

A note on the unsteady flow of dusty viscous fluid between two parallel plates

We study the isothermal flow of a dusty viscous incompressible conducting fluid between two types of boundary motions-oscillatory and non-oscillatory, under the influence of gravitational force. Within the frame work of some physically realistic approximations and suitable boundary conditions, closed form solutions were obtained for the velocity profiles and the skin friction of the particulate flow. These results show that for a constant pressure gradient, only the velocity profile of the fluid and the skin friction are unaffected by gravity, while magnetic field is seen to affect both the fluid, particle velocities and the skin friction. Thus, our results are extension of previous results in literature, and graphical demonstration of some these solutions have been presented.     

On the unsteady flow and temperature distribution of a viscous incompressible fluid between two parallel flat plates

The unsteady flow and temperature distribution of a viscous incompressible fluid between two parallel flat plates has been investigated. The pressure gradient is varying linearly with time. The velocity and temperature profiles for various values oft have been shown graphically. Fort = 0, the velocity and temperature profiles correspond to the plane Poiseuille flow. The velocity and temperature both increase with time and they are maximum on the central plane of the channel.     

Steady plane-parallel flow of an anomalously viscous fluid between parallel plates

The authors consider the plane-parallel flow of an anomalously viscous fluid between two parallel plates, one of which is fixed while the other moves at constant velocity. An empirical power law is used as the rheological equation of state. It is shown that in the presence of a counterpressure exceeding a certain value, which is a function of the rheological properties of the polymer, the geometry and the flow regime, a counterflow develops near the bottom of the channel. The existence of a counterflow leads to the appearance of a minimum on the V_X(y) curve. This additional boundary condition makes it possible to obtain an approximate solution of the differential equations of motion and to describe the velocity distribution in the flow by means of two exponential equations. Integration of the velocity distribution thus obtained over the height of the channel gives an equation for the volume flow rate in plane-parallel flow in the presence of a counterpressure. It is shown that if the counterpressure gradient exceeds a critical value, the volume flow rate decreases much more sharply than for a Newtonian fluid.Mekhanika Polimerov, Vol. 1, No. 6, pp. 138–145, 1965     

An unified numerical approach of steady convection between two parallel plates

This paper considers the problem of laminar forced convection between two parallel plates. We present an unified numerical approach for some problems related to this case: the problem of viscous dissipation with Dirichlet and Neumann boundary conditions and the Graetz problem. The solutions of these problems are obtained by a series expansion of the complete eigenfunctions system of some Sturm-Liouville problems. The eigenfunctions and eigenvalues of this Sturm-Liouville problem are obtained by using Galerkin’s method. Numerical examples are given for viscous fluids with various Brinkman numbers.     

The flow of a variable viscosity fluid between parallel plates with shear heating

A model for the flow of a fluid through a channel with parallel plates is investigated. The channel is narrow, so that the lubrication approximation may be applied. The channel walls are maintained at a constant temperature. Shear heating effects are included and the fluid viscosity decreases exponentially with temperature. When the flow is driven solely by shear stress or imposed velocity at the top, analytical progress is possible. When pressure gradient also drives the flow the problem is solved numerically.     

Inclined magnetic field and Soret effects on mixed convection flow between vertical parallel plates

This present paper investigates the influence of thermal diffusion and inclined magnetic field effects on mixed convection flow through a channel. Spectral Quasilinearization Method (SQLM) is used to solve the dimensionless governing equations, those were obtained by using sutable transformations from the system of governing partial differential equations. The influence of the variation of different parameters like magnetic parameter, Hall parameter, Soret parameter and the intensity of angle of inclination on velocities, temperature and concentration are investigated and presented through plots. According to acquired results, under the influence of magnetic field (in an inclined direction) the velocity profiles were amplified and the temperature profile got diminished, where as there is a reverse tendency under the effect of Hall parameter. Finally the nature of the physical parameters were displayed in table form.     

Bounds on the transport of mass and momentum by turbulent flow between parallel plates

Zusammenfassung Es werden exakte Schranken für den Transport von Impuls in der turbulenten ebenen Couette-Strömung und für den Durchfluss in turbulenter Poiseuille Strömung abgeleitet. Eine der beiden jeweiligen Schranken ist durch den der laminaren Strömung entsprechenden Wert gegeben. Die andere Schranke wird mit Hilfe eines Variationsproblems bestimmt. Ähnliche Schranken lassen sich in anderen turbulenten Transportproblemen gewinnen. Das Variationsproblem enthält als Spezialfall das Reynolds-Orrsche Variationsproblem, durch welches eine untere Grenze für die Reynoldszahl bestimmt wird, unterhalb derer die laminare Strömung absolut stabil ist.     

Analytical solution for the unsteady MHD flow of a viscous fluid between moving parallel plates

Two-dimensional unsteady MHD flow of a viscous fluid between two moving parallel plates is considered. We allow the plates to move together as well as apart: When the plates move together it corresponds to squeezing flow problem. The governing Navier–Stokes equations for the flow are reduced to a fourth order nonlinear ODE and analytical solutions are obtained for the ODE via the homotopy analysis method. We show that the flow is strongly influenced by the strength of the magnetic field and the density of the fluid. Furthermore, an error analysis for the obtained solutions is provided.     

On the steady flow of a Newtonian fluid between two parallel disk

Summary We show that the steady flow of a viscous fluid of moderate Reynolds number between two parallel disks has an exact solution which takes the form of a power series. Employing this exact solution the two-point boundary value problem for this class of flow is reduced to a nonlinear algebraic system which is then solved by a standard optimization method. Results are given for two particular cases, the continuous squeezing flow and the coaxial-disk flow.

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Zusammenfassung Wir zeigen, daß die ständige Strömung einer viskosen Flüssigkeit von mäßiger Reynoldszahl zwischen zwei parallelen Scheiben eine exakte Lösung hat, die die Form einer Potenzreihe annimmt. Wenn wir diese exakte Lösung anwenden, wird das Zwei-Punkte-Grenzwertproblem für diese Art von Strömung reduziert auf ein nichtlineares algebraisches System, das dann durch eine Optimierungsmethode gelöst werden kann. Angegeben werden Resultate für zwei Einzelfälle: die kontinuierliche Quetschströmung und die Strömung für Koaxialscheiben.