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Article

Jitendra Kumar Singh, Gauri Shenker Seth and Saikh Ghousia Begum

The purpose of this paper is to present an analytical study on an unsteady magnetohydrodynamic (MHD) boundary layer flow of a rotating viscoelastic fluid over an infinite…

Abstract

Purpose

The purpose of this paper is to present an analytical study on an unsteady magnetohydrodynamic (MHD) boundary layer flow of a rotating viscoelastic fluid over an infinite vertical porous plate embedded in a uniform porous medium with oscillating free-stream taking Hall and ion-slip currents into account. The unsteady MHD flow in the rotating fluid system is generated due to the buoyancy forces arising from temperature and concentration differences in the field of gravity and oscillatory movement of the free-stream.

Design/methodology/approach

The resulting partial differential equations governing the fluid motion are solved analytically using the regular perturbation method by assuming a very small viscoelastic parameter. In order to note the influences of various system parameters and to discuss the important flow features, the numerical results for fluid velocity, temperature and species concentration are computed and depicted graphically vs boundary layer parameter whereas skin friction, Nusselt number and Sherwood number at the plate are computed and presented in tabular form.

Findings

An interesting observation is recorded that there occurs a reversal flow in the secondary flow direction due to the movement of the free stream. It is also noted that a decrease in the suction parameter gives a rise in momentum, thermal and concentration boundary layer thicknesses.

Originality/value

Very little research work is reported in the literature on non-Newtonian fluid dynamics where unsteady flow in the system arises due to time-dependent movement of the plate. The motive of the present analytical study is to analyse the influences of Hall and ion-slip currents on unsteady MHD natural convection flow of a rotating viscoelastic fluid (non-Newtonian fluid) over an infinite vertical porous plate embedded in a uniform porous medium with oscillating free-stream.

Details

Multidiscipline Modeling in Materials and Structures, vol. 14 no. 2
Type: Research Article
ISSN: 1573-6105

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Article

S. Das, Asgar Ali and R.N. Jana

This paper aims to present the analytical investigation on an unsteady magneto-convective rotation of an electrically conducting non-Newtonian Casson hybrid nanoliquid…

Abstract

Purpose

This paper aims to present the analytical investigation on an unsteady magneto-convective rotation of an electrically conducting non-Newtonian Casson hybrid nanoliquid past a vertical porous plate. The effects of thermal radiation, heat source/sink and hydrodynamic slip phenomenon are also taken into account. Ethylene glycol (EG) is adopted as a base Casson fluid. The Casson fluid model is accounted for to describe the rheological characteristics of non-Newtonian fluid. EG with copper and alumina nanoparticles is envisaged as a non-Newtonian Casson hybrid nanoliquid. The copper-alumina-ethylene glycol hybrid nanoliquid is considered as the regenerative coolant.

Design/methodology/approach

The perturbation method is implemented to develop the analytical solution of the modeled equations. Acquired solutions are used to calculate the shear stresses and the rate of heat transfer in terms of amplitudes and phase angles. Numerical results are figured out and tabled to inspect the physical insights of various emerging parameters on the pertinent flow characteristics.

Findings

This exploration discloses that the velocity profiles are strongly diminished by the slip parameter. Centrifugal and Coriolis forces caused by the plate rotation are found to significantly change the entire flow regime. The supplementation of nanoparticles is to lessen the amplitude of the heat transfer rate. A comparative study is carried out to understand the improvement of heat transfer characteristics of Casson hybrid nanoliquid and Casson nanoliquid. However, the Casson hybrid nanoliquid exhibits a lower rate of heat transfer than the usual Casson nanoliquid.

Practical implications

This proposed model would be pertinent in oceanography, meteorology, atmospheric science, power engineering, power and propulsion generation, solar energy transformation, thermoelectric and sensing material processing, tumbler in polymer manufacturing, etc. Motivated by such practical implications, the proposed study has been unfolded.

Originality/value

The novelty of this paper is to examine the simultaneous effects of the magnetic field, Coriolis force, suction/injection, slip condition and thermal radiation on non-Newtonian Casson hybrid nanoliquid flow past an oscillating vertical plate subject to periodically heating in a rotating frame of reference. A numerical comparison is also made with the existing published results under some limiting cases and it is found that the results are in good agreement with them. An in-depth review of the literature and the author’s best understanding find that such aspects of the problem have so far remained unexplored.

Details

World Journal of Engineering, vol. 18 no. 1
Type: Research Article
ISSN: 1708-5284

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Article

Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Council, Reports and Technical Memoranda of the United…

Abstract

Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Council, Reports and Technical Memoranda of the United States National Advisory Committee for Aeronautics and publications of other similar Research Bodies as issued.

Details

Aircraft Engineering and Aerospace Technology, vol. 27 no. 1
Type: Research Article
ISSN: 0002-2667

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Article

Arya Ghiasi, Seyed Esmaeil Razavi, Abel Rouboa and Omid Mahian

This study aims to investigate the effect of the simultaneous usage of active and passive methods (which in this case are rotational oscillation and attached splitter plate

Abstract

Purpose

This study aims to investigate the effect of the simultaneous usage of active and passive methods (which in this case are rotational oscillation and attached splitter plate, respectively) on the flow and temperature fields to find an optimum situation which this combination results in heat transfer increment and drag reduction.

Design/methodology/approach

The method of the solution was based on finite volume discretization of Navier–Stokes equations. A dynamic grid is coupled with the solver by the arbitrary Lagrangian–Eulerian (ALE) formulation for modeling cylinder oscillation. Parametric studies were performed by altering oscillation frequency, splitter plate length and Reynolds number.

Findings

Oscillation in different frequencies was found to be complicated. Higher frequencies provide more heat transfer, but in the lock-on region, they bring remarkable increment to the drag coefficient. It was observed that simultaneous usage of oscillation and splitter plate may have both positive and negative effects on drag reduction and heat transfer increment. Finally F = 2 and L = 0.5 were chosen as an optimum combination.

Originality/value

In this study, the laminar incompressible flow and heat transfer from a confined rotationally oscillating circular cylinder with an attached splitter plate are investigated. Parametric studies are performed by changing oscillation frequency, splitter plate length and Reynolds number.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 29 no. 5
Type: Research Article
ISSN: 0961-5539

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Article

Jitendra Kumar Singh, Gauri Shenkar Seth, Ghousia Begum and Vishwanath S.

In the present investigation, hydromagnetic boundary layer flow of Walters’-B fluid over a vertical porous surface implanted in a porous material under the action of a…

Abstract

Purpose

In the present investigation, hydromagnetic boundary layer flow of Walters’-B fluid over a vertical porous surface implanted in a porous material under the action of a strong external applied magnetic field and rotation is presented. In several industrial applications, the external applied magnetic field is strong enough to produce Hall and ion-slip currents. Thus, the influence of Hall and ion-slip currents is also considered in this analysis. The flow through configuration is generated because of time varying motion of the free-stream and buoyancy action.

Design/methodology/approach

Regular perturbation scheme is used to obtain the solution of the system of coupled partial differential equations representing the mathematical model of the problem. Numerical computation has been performed to notice the change in flow behavior and the numerical results for velocity field, temperature field, species concentration, skin friction, rate of heat and mass transfer are presented through graphs and tables.

Findings

An important fact noticed that the exponential time varying motion of the free-stream induces reverse flow in the direction perpendicular to the main flow. Rising values of the strength of the applied magnetic field give increment in the fluid velocity in the neighbourhood of the vertical surface, this may cause because of the exponential motion of the free-stream. The behaviour of the Darcian drag force is similar as magnetic field on fluid flow.

Originality/value

In literature, very less research works are available on Walters’-B fluid where unsteadiness in the system occurs because of time varying motion of the free-stream. In this paper, the authors have made an attempt to study the action of Hall and ion-slip currents, rotation and external applied magnetic field on hydromagnetic boundary layer flow of Walters’-B fluid over a vertical surface implanted in a porous material.

Details

World Journal of Engineering, vol. 17 no. 2
Type: Research Article
ISSN: 1708-5284

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Article

B. Mahanthesh, T. Brizlyn, SabirAli Shehzad and Gireesha B.J.

The nonlinear density thermal/solutal fluctuations in the buoyancy force term cannot be ignored when the temperature/concentration difference between the surface and fluid…

Abstract

Purpose

The nonlinear density thermal/solutal fluctuations in the buoyancy force term cannot be ignored when the temperature/concentration difference between the surface and fluid is large. The purpose of this paper is to investigate the nonlinear density fluctuations across a flowing fluid with heat mass transfer effects on a non-axial rotating plate. Therefore, the impact of nonlinear convection in the flow of Casson fluid over an oscillating plate has been analytically investigated.

Design/methodology/approach

The governing equations are modeled with the help of conservation equations of velocity, energy and concentration under the transient-state situation. The dimensional governing equations are non-dimensionalized by utilizing non-dimensional variables. Later, the subsequent non-dimensional problem has been solved analytically using Laplace transform method.

Findings

The effects of thermal Grashof number, solute Grashof number, nonlinear convection parameters, Casson fluid parameter, unsteady parameter, Prandtl number as well as Schmidt number on hydrodynamic, thermal and solute characteristics have been quantified. The numeric data for skin friction coefficient, Nusselt number and Sherwood number are presented. It is established the nonlinear convection aspect has a significant influence on heat and mass transport characteristics.

Originality/value

The effect of nonlinear convection in the dynamics of Casson fluid past an oscillating plate which is rotating non-axially is investigated for the first time.

Details

Multidiscipline Modeling in Materials and Structures, vol. 15 no. 4
Type: Research Article
ISSN: 1573-6105

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Article

M. Mahbubur Razzaque and Muhannad Mustafa

The purpose of this paper is to present a parametric study of the effects of permeability and surface roughness on the hydrodynamic force and the leakage flow rate in an…

Abstract

Purpose

The purpose of this paper is to present a parametric study of the effects of permeability and surface roughness on the hydrodynamic force and the leakage flow rate in an oscillating squeeze film between a rigid surface and a rubber surface.

Design/methodology/approach

The study is conducted numerically using a squeeze film model that incorporates the effects of viscoelasticity, permeability and surface roughness.

Findings

It is seen that with increasing permeability of the porous rubber block, both the hydrodynamic force and the leakage flow rate decrease. Increasing center line average (CLA) of surface roughness height distribution decreases the leakage flow rate slightly but increases the hydrodynamic force. The decrease in the hydrodynamic force due to using permeable material in squeeze film may be compensated for by deliberately increasing the surface roughness. The effect of variation in frequency of system vibration may be minimized by using optimally selected permeable materials with rough surface.

Originality/value

The paper reports the extension of previous work of the authors and the results of this portion were never published. The findings of this paper are based on original work and have practical value.

Details

Industrial Lubrication and Tribology, vol. 65 no. 1
Type: Research Article
ISSN: 0036-8792

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Article

Constantin Fetecau, Shahraz Akhtar, Ioan Pop and Corina Fetecau

The purpose of this note is to provide general solutions for radiative magnetohydrodynamic natural convection flow.

Abstract

Purpose

The purpose of this note is to provide general solutions for radiative magnetohydrodynamic natural convection flow.

Design/methodology/approach

To obtain exact solutions for such motions of Newtonian fluids, as seen in the existing literature, the Laplace transform technique is used.

Findings

General solutions are obtained for temperature, velocity and Nusselt number in the presence of heat source and shear stress on the boundary. They can generate exact solutions for any motion with technical relevance of this type. Fluid velocity is presented as the sum of mechanical and thermal components. Influence of physical parameters on temperature and velocity is graphically underlined for ramp-type heating plate that applies a constantly accelerating shear stress to the fluid. Thermal and mechanical effects are significant and must be taken into consideration.

Practical implications

For illustration, as well as for a check of results, three special cases with applications in engineering are considered and some known results are recovered.

Originality/value

Obtained solutions are presented in the simplest forms. In addition, the solutions corresponding to cosine oscillatory heating and oscillating shear are presented so that they can be immediately reduced to those corresponding to constant heating and uniform shear if the oscillations’ frequency becomes zero. Heat transfer characteristics with thermal radiation are graphically illustrated using one parameter only for such motions.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 27 no. 6
Type: Research Article
ISSN: 0961-5539

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Article

Joaquin Ortega-Casanova and Ramon Fernandez-Feria

This paper aims to consider the thrust force generated by two plunging and pitching plates in a tandem configuration in forward flight to find out the configuration that…

Abstract

Purpose

This paper aims to consider the thrust force generated by two plunging and pitching plates in a tandem configuration in forward flight to find out the configuration that maximizes the propulsive efficiency with high-enough time-averaged lift force.

Design/methodology/approach

To that end, the Navier–Stokes equations for the incompressible and two-dimensional flow at Reynolds number $500 are solved. As the number of parameters is quite large, the case of constant separation between the plates (half their chord length), varying seven non-dimensional parameters related to the phase shift between the heaving motion of the foils, the phase lag between pitch and heave of each plate independently and the frequency and amplitude of the heaving and pitching motions are considered. This analysis complements some other recent studies where the separation between the foils has been used as one of the main control parameters.

Findings

It is found that the propulsive efficiency is maximized for a phase shift of 180° (counterstroking), when the reduced frequency is 2.2 and the Strouhal number based on half the plunging amplitude is 0.17, the pitching amplitude is 25° and when pitch leads heave by 135° in both the fore -plate and the hind plate. The propulsive efficiency is about 20 per cent, just a bit larger than that of an isolate plate with the same motion as the fore-plate, but the corresponding lift force is negligible for a single plate. The paper discusses this vortical flow structure in relation to other less efficient ones. Finally, the effect of the separation between the plates and the Reynolds number is also briefly discussed.

Originality/value

The kinematics of two flapping plates in tandem configuration that maximizes the propulsive efficiency are characterized discussing physically the associated vortical flow structures in comparison with less efficient kinematic configurations. A much larger number of parameters in the optimization procedure than in previous related works is considered.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 29 no. 11
Type: Research Article
ISSN: 0961-5539

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Article

Mahantesh M. Nandeppanavar, Kemparaju M.C. and N. Raveendra

This paper aims to report the investigation of over heat and mass transfer of convective Casson fluid flow over a moving vertical plate with nonlinear thermal radiation…

Abstract

Purpose

This paper aims to report the investigation of over heat and mass transfer of convective Casson fluid flow over a moving vertical plate with nonlinear thermal radiation and convective boundary conditions.

Design/methodology/approach

The main partial differential equations of the flow, heat and concentration profiles were rehabilitated to nonlinear ordinary differential equations by using an appropriate similarity transformation. The resultant nonlinear ordinary differential equations (ODEs) are solved numerically applying fourth-order Runge–Kutta shooting technique and functions of ODE45 from MATLAB.

Findings

The effect of convective heat transfer, buoyancy ratio parameter, nonlinear thermal radiation, Prandtl number, Rayleigh number and Schmidt number over velocity, temperature and concentration profiles, equivalent to abundant somatic parameters were graphically scrutinized.

Originality/value

All the results are very promising and further there is got good agreement of results when compared with earlier published results at limiting conditions.

Details

World Journal of Engineering, vol. 18 no. 1
Type: Research Article
ISSN: 1708-5284

Keywords

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