The Effects of Electrical Conductivity on Fluid Flow between Two Parallel Plates in a Porous Medioum

This paper deals with a mathematical model of a fluid flowing between two parallel plates in a porous medium under the influence of electromagnetic forces (EMF). The continuity, momentum, and energy equations were utilized to describe the flow. These equations were stated in their nondimensional forms and then processed numerically using the method of lines. Dimensionless velocity and temperature profiles were also investigated due to the impacts of assumed parameters in the relevant problem. Moreover, we investigated the effects of Reynolds number , Hartmann number M, magnetic Reynolds number , Prandtl number , Brinkman number , and Bouger number , beside those of new physical quantities (N , ). We solved this system by creating a computer program using MATLAB.

HEAT EXCHANGE OF ELECTRIC CONDUCTIVE LIQUID IN THE SUPPLY OF HEAT TO THE INNER SURFACE OF THE SPHERICAL LAYER AT SMALL VALUES OF THE REYNOLD'S MAGNETIC NUMBER

Представлены результаты численного моделирования нестационарного теплообмена и магнитной гидродинамики электропроводной жидкости в сферическом слое. Исследовано влияние малых значений магнитного числа Рейнольдса и теплоты джоулевой диссипации на эволюцию структуры течения жидкости, поле температуры, магнитной индукции и распределение чисел Нуссельта. The results of numerical simulation of unsteady heat transfer and magneto hydrodynamics of an electrically conductive fluid in a spherical layer are presented. The influence of small values of the magnetic Reynolds number and the heat of Joule dissipation on the evolution of the structure of the fluid flow, the field of temperature, magnetic induction and the distribution of Nusselt numbers is investigated.

HEAT EXCHANGE OF ELECTRIC CONDUCTIVE LIQUID WHEN DEPLOYING THE HEAT FROM THE INNER SURFACE OF THE SPHERICAL LAYER AT SMALL VALUES OF THE REYNOLD'S MAGNETIC NUMBER

Представлены результаты численного моделирования нестационарного теплообмена и магнитной гидродинамики электропроводной жидкости в сферическом слое. Исследовано влияние малых значений магнитного числа Рейнольдса и диссипации джоулевой теплоты на эволюцию структуры течения жидкости, поле температуры, магнитной индукции и распределение чисел Нуссельта. The results of numerical simulation of unsteady heat transfer and magneto hydrodynamics of an electrically conductive fluid in a spherical layer are presented. The influence of small values ​​of the magnetic Reynolds number and dissipation of Joule heat on the evolution of the structure of the fluid flow, the field of temperature, magnetic induction and the distribution of Nusselt numbers is investigated.

Magnetic Field Effects On Backward-facing Step Flow of Ferrofluids

Backward-facing step (BFS) flow is a benchmark case study in fluid mechanics. Its control by means of electromagnetic actuation has attracted great interest in recent years. This paper focuses on the effects of a uniform stationary magnetic field on the laminar ferrofluid BFS flows for the Reynolds number range 0.1=Re=400 and different expansion ratios. The coupled ferrohydrodynamic equations, including the microscopically derived magnetization equation, for a two-dimensional domain are solved numerically by an Open FOAM solver after validation and a test of accuracy. The application of a magnetic field causes the corner vortices in the concave corner behind the step to be retracted compared with their positions in the absence of a magnetic field. The maximum percentage of the normalized decrease in length of these eddies reaches 41.23% in our simulations. For small Reynolds numbers (<10), the flow separation points on the convex corner are lowered in the presence of a magnetic field. Furthermore, the dimensionless total pressure drop between the channel inlet and outlet decreases almost linearly with Reynolds number Re, but the drop is greater when a magnetic field is applied. On the whole, the normalized recirculation length of the corner vortex increases nonlinearly with increasing magnetic Reynolds number Rem and Brownian Péclet number Pe, but it tends to constant values in the limits Re ≪ 1 and Re ≫ 1.

Shear-driven Hall-magnetohydrodynamic dynamos

Nonlinear Hall-magnetohydrodynamic dynamos associated with coherent structures in subcritical shear flows are investigated by using unstable invariant solutions. The dynamo solution found has a relatively simple structure, but it captures the features of the typical nonlinear structures seen in simulations, such as current sheets. As is well known, the Hall effect destroys the symmetry of the magnetohydrodynamic equations and thus modifies the structure of the current sheet and mean field of the solution. Depending on the strength of the Hall effect, the generation of the magnetic field changes in a complex manner. However, a too strong Hall effect always acts to suppress the magnetic field generation. The hydrodynamic/magnetic Reynolds number dependence of the critical ion skin depth at which the dynamos start to feel the Hall effect is of interest from an astrophysical point of view. An important consequence of the matched asymptotic expansion analysis of the solution is that the higher the Reynolds number, the smaller the Hall current affects the flow. We also briefly discuss how the above results for a relatively simple shear flow can be extended to more general flows such as infinite homogeneous shear flows and boundary layer flows. The analysis of the latter flows suggests that interestingly a strong induction of the generated magnetic field might occur when there is a background shear layer.

Hall and ion slip impacts on Unsteady MHD Convective flow of Ag–TiO2/WEG hybrid nanofluid in a rotating frame

Background: It is discussed the radiative magnetohydrodynamic (MHD) flow of an incompressible viscous electrically conducting hybrid nanoliquid over an exponentially accelerated vertical surface under the influence of slip velocity in a rotating frame taking Hall and ion slip impacts into account. Methods: Water and ethylene glycol mixture have been considered as a base fluid. A steady homogeneous magnetic field is applied under the assumption of low magnetic Reynolds number. The ramped temperature and time varying concentration at the surface is made into consideration. The first order consistent chemical reaction and heat absorption are also regarded. Silver (Ag) and titania (TiO2) nanoparticles are disseminated in base fluid water and ethylene glycol mixture to be formed hybrid nanofluid. Results: The Laplace transformation technique is employed on the non-dimensional governing equations for the closed form solutions. Based on these outcomes, the phrases for non-dimensional shear stresses, rates of heat and mass transfer are also evaluated. The graphical representations are presented to scrutinize the effects of physical parameters on the significant flow characteristics. The computational values of the shear stresses, rates of heat and mass transports near the surface are tabulated by a range of implanted parameters. Conclusion: The resultant velocity is growing by an increasing in thermal and concentration buoyancy forces, Hall and ion-slip parameters, whereas rotation and slip parameters have overturn outcome on it. The temperature of hybrid Ag-TiO2/WEG nanofluid is relatively superior to that of Ag-WEG nanofluid. Species concentration of hybrid Ag-TiO2/WEG nanofluid is decreased with an increasing in Schmidt number and chemical reaction parameter.

A simple scenario of the laminar breakdown in liquid metal flows

In the article, authors present a numerical method for modelling a laminar-turbulent transition in magnetohydrodynamic flows. The small magnetic Reynolds number approach is considered. Velocity, pressure and electrical potential are decomposed to the sum of state values and finite amplitude perturbations. A solver based on the Nektar++ framework is described. The authors suggest using small-length local perturbations as a transition trigger. They can be imposed by blowing or by electrical enforcing. The stability of the Hartmann flow and the flow in the bend are considered as examples. Tables 4, Figs 19, Refs 28.