On MHD radiative Jeffery nanofluid flow with convective heat and mass boundary conditions

Neural Computing and Applications - The prime objective of present exploration is to study effects of magnetohydrodynamic, Joule heating and thermal radiation on an incompressible Jeffrey nanofluid...     

A revised model to study the MHD nanofluid flow and heat transfer due to rotating disk: numerical solutions

Here our main interest is to present numerical simulations for magneto-nanofluid flow and heat transfer near a rotating disk. Buongiorno model, featuring the novel aspects of Brownian motion and thermophoresis, is accounted. Heat dissipation effect is preserved in the energy balance equation. We take into account more realistic wall condition which requires passive control of nanoparticle concentration at the disk. The traditional Von Karman relations have been invoked to attain self-similar differential system. Keller–Box method has been implemented to compute similarity solutions of the problem. Streamlines are prepared in both two and three dimensions for adequate flow visualization. The behavior of involved parameters on the flow fields is examined graphically. It is predicted that the torque required to maintain disk in steady rotation increases when magnetic field effects are enhanced. Fluid flow in the radial, azimuthal and vertical directions is opposed by the magnetic field strength. Thermophoresis effect enhances temperature and reduces heat flux from the disk. However, Brownian diffusion has a marginal influence on temperature distribution. Heat transfer coefficient is reduced due to the inclusion of heat dissipation terms. Present results are consistent with those of the available studies in a limiting situation.

     

Numerical study of asymmetric laminar flow of micropolar fluids in a porous channel

A numerical study is presented for the two-dimensional flow of a micropolar fluid in a porous channel. The channel walls are of different permeability. The fluid motion is superimposed by the large injection at the two walls and is assumed to be steady, laminar and incompressible. The micropolar model due to Eringen is used to describe the working fluid. The governing equations of motion are reduced to a set of non-linear coupled ordinary differential equations (ODEs) in dimensionless form by using an extension of Berman’s similarity transformations. A numerical algorithm based on finite difference discretization is employed to solve these ODEs. The results obtained are further improved by Richardson’s extrapolation for higher order accuracy. Comparisons with the previously published work are performed and are found to be in a good agreement. It has been observed that the velocity and microrotation profiles change from the most asymmetric shape to the symmetric shape across the channel as the parameter R or the permeability parameter A are varied between their extreme values. The results indicate that larger the injection velocity at a wall relative to the other is, smaller will be the shear stress at it than that at the other. The position of viscous layer has been found to be more sensitive to the permeability parameter A than to the parameter R. The micropolar fluids reduce shear stress and increase couple stress at the walls as compared to the Newtonian fluids.     

MHD flow with heat and mass transfer of Williamson nanofluid over stretching sheet through porous medium

Microsystem Technologies - Two-dimensional hydromagnetic flow of an incompressible Williamson nanofluid over a stretching sheet in a porous media is examined during this work. Convective heat and...     

Convective Poiseuille flow of Al2O3-EG nanofluid in a porous wavy channel with thermal radiation

In current article, convective Poiseuille boundary layer flow of ethylene glycol (C₂H₆O₂)-based nanofluid with suspended aluminum oxide (Al₂O₃) nanoparticles through a porous wavy channel has been examined. The impact of thermal radiation, Ohmic dissipation, electric field, and magnetic fields are also considered. The flow is due to constant pressure gradient in a wavy frame of reference. The governed momentum and thermal boundary layer equations is system of PDE’s, which are converted to system of ODE’s via suitable similarity transformations. The homotopy analysis method is applied to solve the governed flow problem. Convergence of series solutions is inspected through h-curves and residual errors norm, whereas the optimal value of convergence control parameter is obtained by means of genetic algorithm Nelder–Mead approach. The influence of numerous involving parameters like Hartmann number, Grashof number, Eckert number, electric parameter, radiation parameter, and porosity parameter on flow, heat transfer, skin friction coefficient and Nusselt number are illustrated through graphs and discussed briefly.

     

Onset of double-diffusive convection of a sparsely packed micropolar fluid in a porous medium layer saturated with a nanofluid

The onset of convection of a sparsely packed micropolar fluid in a porous medium layer saturated by a nanofluid is examined by using a linear and nonlinear stability analyses. The Darcy–Brinkman–Forchheimer model is employed for the porous medium layer. The model used for the nanofluid incorporates the effects of Brownian motion and thermophoresis. The critical Rayleigh number, wave number for stationary and oscillatory modes and frequency of oscillations are obtained analytically using linear theory, and the nonlinear analysis is made with minimal representation of the truncated Fourier series analysis involving only two terms. The effect of various parameters on the stationary and oscillatory convections is shown pictorially. The dependence of stationary or oscillatory convection on the porous parameter and parameters involved in micropolar fluids is also discussed. We also study the effect of time on transient Nusselt number and Sherwood number which are found to be oscillatory when time is small. However, when time becomes very large, both the transient Nusselt value and Sherwood value approach to their steady-state values.     

Investigation of MHD effects on micropolar–Newtonian fluid flow through composite porous channel

Microfluidics and Nanofluidics - We discuss the rotational force-induced flow dynamics of a viscoplastic fluid in a polymeric layer grafted soft microfluidic channel. In this analysis, the...     

Electromagnetohydrodynamic nanofluid flow past a porous Riga plate containing gyrotactic microorganism

Neural Computing and Applications - Here we have numerically examined the effects of EMHD in flow of nanofluid past a porous Riga surface with gyrotactic microorganism and nanoparticles. Modeling...     

Magnetohydrodynamic (MHD) flow of a micropolar fluid towards a stagnation point on a vertical surface

The steady MHD mixed convection stagnation point flow towards a vertical surface immersed in an incompressible micropolar fluid is investigated. The external velocity impinges normal to the wall and the wall temperature is assumed to vary linearly with the distance from the stagnation point. The governing partial differential equations are transformed into a system of ordinary differential equations, which is then solved numerically by a finite-difference method. The features of the flow and heat transfer characteristics for different values of the governing parameters are analyzed and discussed. Both assisting and opposing flows are considered. It is found that dual solutions exist for the assisting flow, besides that usually reported in the literature for the opposing flow.     

Numerical simulation for MHD flow of Sisko nanofluid over a moving curved surface: A revised model

Microsystem Technologies - An analysis regarding diverse features of Sisko fluid flow over a curved stretching surface in the presence of magneto-nanoparticles is presented. For larger value of the...     

Computer simulation of MHD blood conveying gold nanoparticles as a third grade non-Newtonian nanofluid in a hollow porous vessel

In this paper, heat transfer and flow analysis for a non-Newtonian third grade nanofluid flow in porous medium of a hollow vessel in presence of magnetic field are simulated analytically and numerically. Blood is considered as the base third grade non-Newtonian fluid and gold (Au) as nanoparticles are added to it. The viscosity of nanofluid is considered a function of temperature as Vogel's model. Least Square Method (LSM), Galerkin method (GM) and fourth-order Runge–Kutta numerical method (NUM) are used to solve the present problem. The influences of the some physical parameters such as Brownian motion and thermophoresis parameters on non-dimensional velocity and temperature profiles are considered. The results show that increasing the thermophoresis parameter (N_t) caused an increase in temperature values in whole domain and an increase in nanoparticles concentration just near the inner wall of vessel. Furthermore by increasing the MHD parameter, velocity profiles decreased due to magnetic field effect.     

Homotopy perturbation method for couple stresses effect on MHD peristaltic flow of a non-Newtonian nanofluid

Microsystem Technologies - An analytical study is presented for couple stresses effects on MHD peristaltic transport of a non-Newtonian Jeffery nanofluid. The fluid flows through a porous media...     

Hydromagnetic nanofluid flow past a stretching cylinder embedded in non-Darcian Forchheimer porous media

The present article presents the hydromagnetic nanofluid flow past a stretching cylinder embedded in non-Darcian Forchheimer porous media by using Buongiorno’s mathematical model (Buongiorno in J Heat Transf 128:240–250, 2006; Nadeem et al. in J Taiwan Inst Chem Eng 45:121, 2014, Nadeem et al. Appl Nanosci 4:625–631, 2014). Thermal radiation via Roseland’s approximation (Akbar et al. in Chin J Aeronaut 26:1389–1397, 2013; Nadeem and Haq in J Aerosp Eng 28:04014061, 2012), Brownian motion, thermophoresis and Joule heating effects are also considered. To explore thermal characteristics, prescribed heat flux and prescribed mass flux boundary conditions are deployed. Governing flow problem consists of PDEs in the cylindrical form, which are converted into system of nonlinear ODEs by applying applicable similarity transforms. ODEs are tackled by RK–Fehlberg fourth–fifth-order numerical integration scheme with shooting algorithm. Impact of numerous involving physical parameters on flow features like temperature distribution, velocity distribution, Sherwood number, local Nusselt number and skin friction coefficient is shown through graphs and tables.

     

Soret and MHD effects on bioconvection wall jet flow of nanofluid containing gyrotactic microorganisms

Various applications of bioconvection phenomena in the field of medicine and biotechnology boost us to present the study of laminar wall jet flow in this specific direction. For the purpose, we have considered nanofluid containing gyrotactic microorganisms in the presence of normally applied magnetohydrodynamic forces along with Soret effects. Boundary layer approximation and similarity transformation are utilized to convert governing equations into ordinary differential equations. Influence of different emerging parameters on velocity, temperature and concentration profiles of solute, nanoparticle and motile microorganisms has been investigated. The role of physical quantities like Nusselt number, Sherwood number and density number of microorganisms is also highlighted. Increase in Nusselt number and density number of motile microorganism is observed for incremental values of bioconvection Peclet number. Soret number reflects increasing effect on Nusselt number and decreasing effect on Sherwood number because solute diffusion faces resistance due to higher values of Soret number and in return decreases rate of mass transfer. Also bioconvection Rayleigh number imposes decreasing effect on density number of the motile microorganisms.

     

MHD flow in porous medium induced by torsionally oscillating disk

The unsteady laminar flow of an incompressible, viscous, electrically conducting fluid in porous medium fully saturated with the liquid and bounded by torsionally oscillating disk in the presence of a transverse magnetic field has been computed. It is assumed that the flow between the disk and the porous medium is governed by Navier-Stokes equation and that in the porous medium by Brinkman equation. Flows in the two regions are matched at the interface by assuming that the velocity and stress components are continuous at it. Approximate solutions of the flow characteristics are obtained. Numerical results are presented graphically and discussed.     

The numerical solution of two-dimensional flow in a branching channel

A numerical method for treating the steady two-dimensional flow of a viscous incompressible fluid in a branching channel is given. The Navier-Stokes equations are written in terms of the stream function and vorticity, giving the usual two coupled partial differential equations. These equations are solved using the difference scheme of Dennis and Hudson [Proc. 1^st Cong. Num. Met. Laminar and Turbulent Flow, p. 69. Pentech Press, London (1978)] and a solution to the resulting large system of algebraic equations is obtained using a Gauss-Seidel iteration technique. The upstream and downstream boundary conditions are discussed and a logarithmic transformation is applied to the coordinate measuring distance downstream in order to extend the numerical solution far enough downstream. Two methods are presented for dealing with the singularity in the vorticity at the sharp corners where the channel bifurcates. The numerical solution is obtained for three separate grid sizes for two different widths of channel downstream of the channel branch. The effect on flow separation of both the variation of Reynolds number and the relative channel width upstream and downstream of the branch are discussed.     

Viscous dissipation and MHD hybrid nanofluid flow towards an exponentially stretching/shrinking surface

Neural Computing and Applications - The impact of viscous dissipation in hybrid nanofluid plays a prominent role in industrial applications, for instance, in polymer processing flows and...     

Slip effects on MHD mixed convection stagnation point flow of a micropolar fluid towards a shrinking vertical sheet

In the present study, the effects of partial slip on steady boundary layer stagnation point flow of an electrically conducting micropolar fluid impinging normally towards a shrinking sheet in the presence of a uniform transverse magnetic field is investigated. A similarity transformation technique is adopted to obtain the self similar ordinary differential equations and then solved numerically using symbolic software MATHEMATICA 7.0. The features of the flow and heat transfer characteristics for different values of the governing parameters are analyzed and discussed through graphs and tables. Both cases of assisting and opposing flows are considered. The physical aspects of the problem are highlighted and discussed.     

Vortex instability of MHD natural convection flow over a horizontal plate in a porous medium

The present work investigates the vortex instability of a horizontal MHD natural convection boundary layer flow in a saturated porous medium including the radiation effect. The numerical results are solves by Keller-Box method incorporated with linear stability theory. The velocity and temperature profiles, local Nusselt number, as well as instability parameters for magnetic parameter M ranging from 0 to 2 and radiation parameter R ranging from 0 to 0.03 are presented. Numerical results showed that, as magnetic parameter M increases or radiation parameter R decreases, the heat transfer rate decrease. In addition, the magnetic effect destabilizes the flow to vortex mode of disturbance, while the radiation effect stabilizes it.     

Heat transfer effects on carbon nanotubes suspended nanofluid flow in a channel with non-parallel walls under the effect of velocity slip boundary condition: a numerical study

The present article is dedicated to analyze the flow and heat transfer of carbon nanotube (CNT)-based nanofluids under the effects of velocity slip in a channel with non-parallel walls. Water is taken as a base fluid, and two forms of CNTs are used to perform the analysis, namely the single- and multi-walled carbon nanotubes (SWCNTs and MWCNTs, respectively). Both the cases of narrowing and widening channel are discussed. The equations governing the flow are obtained by using an appropriate similarity transform. Numerical solution is obtained by using a well-known algorithm called Runge–Kutta–Fehlberg method. The influence of involved parameters on dimensionless velocity and temperature profiles is displayed graphically coupled with comprehensive discussions. Also, to verify the numerical results, a comparative analysis is carried out that ensures the authenticity of the results. Variation of skin friction coefficient and the rate of heat transfer at the walls are also performed. Some already existing solutions of the particular cases of the same problem are also verified as the special cases of the solutions obtained here.