scholarly journals Numerical Investigation of MHD Pulsatile Flow of Micropolar Fluid in a Channel with Symmetrically Constricted Walls

Mathematics ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 1000
Author(s):  
Amjad Ali ◽  
Muhammad Umar ◽  
Zaheer Abbas ◽  
Gullnaz Shahzadi ◽  
Zainab Bukhari ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Pulsatile Flow ◽  
Hartmann Number ◽  
Maximum Flow ◽  
Rotation Velocity ◽  
Function Form ◽  
Governing Equations ◽  
Axial Velocity Component ◽  
Flow Profiles ◽  
Stream Function Form

This article presented an analysis of the pulsatile flow of non-Newtonian micropolar (MP) fluid under Lorentz force’s effect in a channel with symmetrical constrictions on the walls. The governing equations were first converted into the vorticity–stream function form, and a finite difference-based solver was used to solve it numerically on a Cartesian grid. The impacts of different flow controlling parameters, including the Hartman number, Strouhal number, Reynolds number, and MP parameter on the flow profiles, were studied. The wall shear stress (WSS), axial, and micro-rotation velocity profiles were depicted visually. The streamlines and vorticity patterns of the flow were also sketched. It is evident from the numerical results that the flow separation region near constriction as well as flattening of the axial velocity component is effectively controlled by the Hartmann number. At the maximum flow rate, the WSS attained its peak. The WSS increased in both the Hartmann number and Reynolds number, whereas it declined with the higher values of the MP parameter. The micro-rotation velocity increased in the Reynolds number, and it declined with increment in the MP parameter.

scholarly journals Critical Analysis of Magnetohydrodynamic Jeffery-Hamel Flow Using Cu-Water Nanofluid

2016 ◽  
Vol 34 ◽  
pp. 111-126
Author(s):  
Md S Alam ◽  
MAH Khan ◽  
MA Alim
Keyword(s):  
Magnetic Field ◽  
Reynolds Number ◽  
Power Series ◽  
Critical Analysis ◽  
Hartmann Number ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Governing Equations ◽  
Channel Angle ◽  
Analytical Technique

The effects of nanoparticles and magnetic field on the nonlinear Jeffery-Hamel flow using Cuwater nanofluid are analysed in the present study. The basic dimensionless governing equations are solved using power series, which is then analysed by applying a semi-numerical analytical technique called Hermite- Padé approximation. The velocity profiles are presented in convergentdivergent channels for various values of nanoparticles solid volume fraction, Hartmann number, Reynolds number and channel angle. The dominating singularity behavior of the problem is analysed numerically and graphically for nanofluid. The critical relationships among the parameters are also performed qualitatively with the effect of Cu-nanoparticles.GANIT J. Bangladesh Math. Soc.Vol. 34 (2014) 111-126

scholarly journals Effect of magnetic field on nanofluid free convection in Conical Partially Annular Space

2020 ◽  
Vol 330 ◽  
pp. 01005
Author(s):  
Abderrahmane AISSA ◽  
Mohamed Amine MEDEBBER ◽  
Khaled Al-Farhany ◽  
Mohammed SAHNOUN ◽  
Ali Khaleel Kareem ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Hartmann Number ◽  
Volume Fraction ◽  
Boussinesq Approximation ◽  
Simulation Software ◽  
Comsol Multiphysics ◽  
Governing Equations ◽  
Element Analysis ◽  
Vertical Side ◽  
Side Walls

Natural convection of a magneto hydrodynamic nanofluid in a porous cavity in the presence of a magnetic field is investigated. The two vertical side walls are held isothermally at temperatures Th and Tc, while the horizontal walls of the outer cone are adiabatic. The governing equations obtained with the Boussinesq approximation are solved using Comsol Multiphysics finite element analysis and simulation software. Impact of Rayleigh number (Ra), Hartmann number (Ha) and nanofluid volume fraction (ϕ) are depicted. Results indicated that temperature gradient increases considerably with enhance of Ra and ϕ but it reduces with increases of Ha.

scholarly journals Conducting dusty fluid flow through a constriction in a porous medium

2016 ◽  
Vol 5 (1) ◽  
pp. 29
Author(s):  
Madhura K R ◽  
Uma M S
Keyword(s):  
Porous Medium ◽  
Hartmann Number ◽  
Equations Of Motion ◽  
Fluid Phase ◽  
Dust Particles ◽  
Governing Equations ◽  
Electrically Conducting ◽  
Electrically Conducting Fluid ◽  
Flow Through ◽  
Constricted Channel

<p><span lang="EN-IN">The flow of an unsteady incompressible electrically conducting fluid with uniform distribution of dust particles in a constricted channel has been studied. The medium is assumed to be porous in nature. The governing equations of motion are treated analytically and the expressions are obtained by using variable separable and Laplace transform techniques. The influence of the dust particles on the velocity distributions of the fluid are investigated for various cases and the results are illustrated by varying parameters like Hartmann number, deposition thickness on the walls of the cylinder and the permeability of the porous medium on the velocity of dust and fluid phase.</span></p>

Effects of Viscous Dissipation and Radiation on MHD Natural Convection in Oblique Porous Cavity with Constant Heat Flux

2017 ◽  
Vol 9 (2) ◽  
pp. 463-484 ◽  
Author(s):  
Ammar I. Alsabery ◽  
Habibis Saleh ◽  
Ishak Hashim
Keyword(s):  
Heat Flux ◽  
Natural Convection ◽  
Viscous Dissipation ◽  
Inclination Angle ◽  
Hartmann Number ◽  
Constant Heat Flux ◽  
Governing Equations ◽  
Constant Heat ◽  
Left Wall ◽  
Porous Cavity

AbstractEffects of viscous dissipation and radiation on MHD natural convection in oblique porous cavity with constant heat flux is studied numerically in the present article. The right inclined wall is maintained at a constant cold temperatureTcand the left inclined wall has a constant heat fluxqwith lengthS, while the remainder of the left wall is adiabatic. The horizontal walls are assumed to be adiabatic. The governing equations are obtained by applying the Darcy model and Boussinesq approximations. COMSOL's finite element method is used to solve the non-dimensional governing equations together with specified boundary conditions. The governing parameters of this study are Rayleigh number (Ra=10,100,200,250,500 and 1000), Hartmann number (0≤Ha≤20), inclination angle of the magnetic field (0° ≤ω≤π/2), Radiation (0≤R≤15), the heater flux length (0.1≤H≤1) and inclination angle of the sloping wall (–π/3≤ϕ≤π/3). The results are considered for various values of the governing parameters in terms of streamlines, isotherms and averageNusselt number. It is found that the intensity of the streamlines and the isotherm patterns decrease with an increment in Hartmann number. The overall heat transfer is significantly increased with the increment of the viscous dissipation and the radiation parameters.

scholarly journals Recurrent flows: the clockwork behind turbulence

2013 ◽  
Vol 726 ◽  
pp. 1-4 ◽  
Author(s):  
Predrag Cvitanović
Keyword(s):  
Fluid Dynamics ◽  
Reynolds Number ◽  
Chaotic Dynamics ◽  
High Dimensional ◽  
Governing Equations ◽  
Infinite Dimensional ◽  
Long Run ◽  
Moderate Reynolds Number ◽  
Dimensional State Space ◽  
Exhaustive Study

AbstractThe understanding of chaotic dynamics in high-dimensional systems that has emerged in the last decade offers a promising dynamical framework to study turbulence. Here turbulence is viewed as a walk through a forest of exact solutions in the infinite-dimensional state space of the governing equations. Recently, Chandler & Kerswell (J. Fluid Mech., vol. 722, 2013, pp. 554–595) carry out the most exhaustive study of this programme undertaken so far in fluid dynamics, a feat that requires every tool in the dynamicist’s toolbox: numerical searches for recurrent flows, computation of their stability, their symmetry classification, and estimating from these solutions statistical averages over the turbulent flow. In the long run this research promises to develop a quantitative, predictive description of moderate-Reynolds-number turbulence, and to use this description to control flows and explain their statistics.

Numerical analysis of Copper-water and Copper-Oxide-water nanofluids flow over a stretching sheet

2020 ◽  
Vol 34 (13) ◽  
pp. 2050130 ◽  
Author(s):  
Salman Ahmad ◽  
M. Ijaz Khan ◽  
T. Hayat ◽  
A. Alsaedi
Keyword(s):  
Reynolds Number ◽  
Nusselt Number ◽  
Comparative Analysis ◽  
Copper Oxide ◽  
Hartmann Number ◽  
Eckert Number ◽  
Nonlinear Pdes ◽  
Surface Drag ◽  
Copper Water ◽  
Flow Variables

Main objective of this paper is to investigate comparative analysis of Copper-water and Copper Oxide-Water nanofluids flow due to a stretchable plate. Magnetic field is applied in transverse direction. Energy equation contains impacts of viscous dissipation and Joule heating. Appropriate dimensionless variables are used to transform the nonlinear PDEs system into dimensionless form. The dimensionless PDEs system is solved numerically by FDM (Finite difference method). Impacts of flow variables including Reynolds number, nanoparticles fraction, Hartmann number and Eckert number on velocity, surface drag force, Nusselt number and temperature are analyzed. Obtained outcomes show that velocity increases through Reynolds number and time while it decreases with Hartmann number. Temperature enhances with Eckert number while it decays with time. Skin friction increases for both Hartmann number and Reynolds number. Nusselt number decreases through nanopartical fraction. Comparative analysis of Copper-water and Copper Oxide-Water nanofluids shows that velocity and temperature are higher in Copper-water when compared with Copper Oxide-Water. For higher nanopartical fraction, the velocity and temperature decrease.

Second Law Analysis of Magneto-Micropolar Fluid Flow Between Parallel Porous Plates

2018 ◽  
Vol 10 (4) ◽  
Author(s):  
Abbas Kosarineia ◽  
Sajad Sharhani
Keyword(s):  
Magnetic Field ◽  
Reynolds Number ◽  
Fluid Flow ◽  
Entropy Generation ◽  
Hartmann Number ◽  
Second Law ◽  
Brinkman Number ◽  
Viscosity Parameter ◽  
Micropolar Fluid Flow ◽  
Second Law Analysis

In this study, the influence of the applied magnetic field is investigated for magneto-micropolar fluid flow through an inclined channel of parallel porous plates with constant pressure gradient. The lower plate is maintained at constant temperature and the upper plate at a constant heat flux. The governing motion and energy equations are coupled while the effect of the applied magnetic field is taken into account, adding complexity to the already highly correlated set of differential equations. The governing equations are solved numerically by explicit Runge–Kutta. The velocity, microrotation, and temperature results are used to evaluate second law analysis. The effects of characteristic and dominate parameters such as Brinkman number, Hartmann Number, Reynolds number, and micropolar viscosity parameter are discussed on velocity, temperature, microrotation, entropy generation, and Bejan number in different diagrams. The results depicted that the entropy generation number rises with the increase in Brinkman number and decays with the increase in Hartmann Number, Reynolds number, and micropolar viscosity parameter. The application of the magnetic field induces resistive force acting in the opposite direction of the flow, thus causing its deceleration. Moreover, the presence of magnetic field tends to increase the contribution of fluid friction entropy generation to the overall entropy generation; in other words, the irreversibilities caused by heat transfer reduced. Therefore, to minimize entropy, Brinkman number and Hartmann Number need to be controlled.

scholarly journals Investigating the Effect of the Closure in Partially-Averaged Navier–Stokes Equations

2019 ◽  
Vol 141 (12) ◽  
Author(s):  
Filipe S. Pereira ◽  
Luís Eça ◽  
Guilherme Vaz
Keyword(s):  
Reynolds Number ◽  
Shear Stress ◽  
Coherent Structures ◽  
Stokes Equations ◽  
The Other ◽  
Navier Stokes ◽  
Governing Equations ◽  
Navier Stokes Equations ◽  
Auxiliary Functions ◽  
Modeling Accuracy

The importance of the turbulence closure to the modeling accuracy of the partially-averaged Navier–Stokes equations (PANS) is investigated in prediction of the flow around a circular cylinder at Reynolds number of 3900. A series of PANS calculations at various degrees of physical resolution is conducted using three Reynolds-averaged Navier–Stokes equations (RANS)-based closures: the standard, shear-stress transport (SST), and turbulent/nonturbulent (TNT) k–ω models. The latter is proposed in this work. The results illustrate the dependence of PANS on the closure. At coarse physical resolutions, a narrower range of scales is resolved so that the influence of the closure on the simulations accuracy increases significantly. Among all closures, PANS–TNT achieves the lowest comparison errors. The reduced sensitivity of this closure to freestream turbulence quantities and the absence of auxiliary functions from its governing equations are certainly contributing to this result. It is demonstrated that the use of partial turbulence quantities in such auxiliary functions calibrated for total turbulent (RANS) quantities affects their behavior. On the other hand, the successive increase of physical resolution reduces the relevance of the closure, causing the convergence of the three models toward the same solution. This outcome is achieved once the physical resolution and closure guarantee the precise replication of the spatial development of the key coherent structures of the flow.

Thermal Fluid Flow Transport Characteristics in Confined Channels With Two-Dimensional Dual Jet Impingement

2011 ◽  
Author(s):  
Caner Senkal ◽  
Shuichi Torii
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Rate ◽  
Inclination Angle ◽  
Transfer Rate ◽  
Velocity Ratio ◽  
Heated Wall ◽  
Outer Diameter ◽  
Stagnation Zone ◽  
Governing Equations

The flow and heat transfer characteristics of laminar dual circular jet impinging on a heating plate with inclined confinement surface has been investigated numerically. Governing equations in steady state are solved by a control volume based finite-difference method. The simulations have been carried out for Reynolds number (250≤Re≤418), the angle of inclination of the confined upper wall (0 ≤ θ ≤ 10), circular jet to annular jet velocity ratio (0≤VR≤2) and jet to target plate distances between 2D and 8D where D is the outer diameter of dual jet.SIMPLE algorithm was used to obtain velocity and temperature fields. Hybrid difference scheme is adopted for the discretized terms in the governing equations. The discretised equations are solved iteratively using the tridiagonal matrix algorithm line solver. Heat transfer performance along the heated wall is amplified with an increase in the velocity ratio and the Reynolds number. On the contrary, a substantial reduction in the heat transfer rate, for VR = 0.0, occurs in the stagnation zone, because the absence of the inner nozzle injection causes the recirculation in the corresponding region. The heat transfer rate in the stagnation zone is attenuated by increasing the jet nozzle to impinging plate distance. In particular, the effect of the inclination angle in the down-stream region, especially at the vicinity of outlet, is major then other effects Nusselt number distribution on the impingement plate is affected by inclined upper wall because inclination of the wall accelerates the exhaust flow. The streamwise reduction in the heat transfer rate for θ = 0° is suppressed by the presence of the inclined confinement surface and its value is intensified by the inclination angle.

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