Modified Hartmann Number Research Articles

Impulsively Started Horizontal Riga Plate Embedded in Unsteady Casson Fluid Flow with Rotation

This article is based on the impulsively started horizontal Riga plate in two dimensional unsteady Casson fluid flows with rotation. The plate starts abruptly from the rest relative to the rotating fluids moving with uniform acceleration in its plane. Numerical solutions are acquired by using explicit finite difference method and estimated results have been gained for various values of the Rotational parameter, modified Hartmann number, Prandtl number, Radiative parameter, Eckert number, Heat source parameter, Schmidt number, and the Soret number. Both the Compaq visual FORTRAN 6.6a and MATLAB R2015a tools have been used to find the numerical solutions and the graphical presentation. The Skin friction, Nusselt number and Sherwood number have been computed and the effects of some pertinent parameters on various distributions are discussed briefly and presented graphically.

Transient electromagnetohydrodynamic radiative squeezing flow between two parallel Riga plates using a spectral local linearization approach

AbstractThis article addresses transient electromagnetohydrodynamic radiative squeezing flow due to convectively heated electromagnetic actuator. The transport analysis of heat and mass is explored considering the heat generation/absorption and destructive species homogeneous reaction. Suitable transformations are applied on the mathematical model developed to convert governing partial differential equations to ordinary differential equations (ODEs). Spectral local linearization method (SLLM) is employed on the resultant nonlinear coupled ODEs to compute the numerical results. Influence of sundry physical quantities on heat mass transfer of squeezing flow characteristics are determined using graphs and tabular results. SLLM results exhibit that momentum and temperature improved with rise in squeezing and heat source parameters correspondingly. Momentum enhances at lower plate and detracts with rise in modified Hartmann number. For improved heat source parameter, the rate of heat transfer diminishes and is more significant for higher Prandtl number values. This investigation has relevance in disk style magnetic clutches, rolling elements, food processing, bearings, squeezing film pressure sensors, and flow rheostats.

BOUNDARY LAYER CONTROL OF A RADIATIVE CASSON FLUID FLOW PAST A PERMEABLE RIGA-PLATE WITH UNIMOLECULAR CHEMICAL REACTION

The buoyancy driven, chemically reacting and radiative Casson fluid flow past an impulsively started permeable Riga-plate is investigated through the numerical solution obtained by Crank-Nicholson implicit scheme of finite difference method. The main aim of this study is to control the boundary layer separation. Escalating modified Hartmann number and the distance from leading edge of the plate reduces the viscous drag so that the separation can be controlled. Effects of permeability on the flow configuration are also elucidated. The results are validated by comparing the solutions of the literature which already exists.

Non-uniform heat source/sink effects on the three-dimensional flow of [formula omitted] /[formula omitted] nanoparticles with different base fluids past a Riga plate

In this study we showed the numerical analysis on the steady, three dimensional flow of different nanofluids past a Riga plate with non-uniform heat source/sink effects. Similarity transformations were used for the conversion of the partial differential equations that govern the flow to the ordinary differential equations. Owing to the complexity in solving these non-linear ordinary differential equations, we employ Runge-Kutta method of fourth order in association with shooting iteration procedure. The three-dimensional flow fields influenced by the parameters pertaining to this problem is discussed with the graphs and tables. The computations on the physical quantities of interest were also performed. The results end up to signify that the local skin friction coefficient enhances for modified Hartmann number and the local Nusselt number is diminished for larger values of heat source/sink parameter. A comparison between the numerical results and already existing data has been done and was found to be in good quantitative agreement.

Viscous Dissipation and Joule Heating Effects in Non-Fourier MHD Squeezing Flow, Heat and Mass Transfer Between Riga Plates with Thermal Radiation: Variational Parameter Method Solutions

A Riga plate is an electromagnetic actuator which comprises permanent magnets and alternating electrodes placed on a plane surface. The present article investigates the influence of viscous and Joule heating (Ohmic dissipation) in the magnetohydrodynamic squeezing flow, heat and mass transfer between two Riga plates. A non-Fourier (Cattaneo–Christov) heat flux model is employed which generalizes the classical Fourier law to incorporate thermal relaxation time. Via suitable transformations, the governing partial differential conservation equations and boundary conditions are non-dimensionalized. The resulting nonlinear ordinary differential boundary value problem is well posed and is solved analytically by the variational parameter method (VPM). Validation of the solutions is included for the special case of non-dissipative flow. Extensive graphical illustrations are presented for the effects of squeeze parameter, magnetic field parameter, modified Hartmann number, radiative parameter, thermal Biot number, concentration Biot number, Eckert number, length parameter, Schmidt number and chemical reaction parameter on the velocity, temperature and concentration distributions. Additionally, the influence of selected parameters on reduced skin friction, Nusselt number and Sherwood number are tabulated. An error analysis is also included for the VPM solutions. Detailed interpretation of the results is provided. The study is relevant to smart lubrication systems in biomechanical engineering and sensor design.

Riga – Plate flow of γ Al2O3-water/ethylene glycol with effective Prandtl number impacts

In many industrial processes, the cooling process can be improved by varying the flow geometry or changing the additives in the working fluid. The present work concentrates on the flow of γ Al2O3 –Water/Ethylene Glycol over a Gailitis and Lielausis device with an effective Prandtl number for the first time. The thermal transport aspects of electro-MHD boundary layer flow of γ Al2O3 nanofluids over a stretchable Riga plate are studied in two dimensions. The wall parallel Lorentz force is produced due to an external electric field by Riga plate to control the nanofluid flow. Mathematical models are developed with an effective Prandtl number. The no-slip and the prescribed surface temperature boundary conditions are assumed. Results are discussed using numerical results obtained by fourth order RK method with shooting technique. Special case analytical solutions are presented for both momentum and energy equations. The increasing behaviour in velocity profile and decreasing behaviours in temperature, skin friction and Nusselt number are observed with increasing modified Hartmann number. The higher modified Hartmann number leads to a sudden enhancement in the velocity profile of the nanofluid in the presence of effective Pr near the riga plate wall.

Simultaneous Effects of Nonlinear Mixed Convection and Radiative Flow Due to Riga-Plate With Double Stratification

This paper addresses nonlinear mixed convection flow due to Riga plate with double stratification. Heat transfer analysis is reported for heat generation/absorption and nonlinear thermal radiation. Physical problem is mathematically modeled and nonlinear system of partial differential equations is achieved. Transformations are then utilized to obtain nonlinear system of ordinary differential equations. Homotopic technique is utilized for the solution procedure. Graphical descriptions for velocity, temperature, and concentration distributions are captured and argued for several set of physical variables. Features of skin friction and Nusselt and Sherwood numbers are also illustrated. Our computed results indicate that the attributes of radiation and temperature ratio variables enhance the temperature distribution. Moreover, the influence of buoyancy ratio and modified Hartmann number has revers effects on rate of heat transfer.

Impacts of variable thermal conductivity on stagnation point boundary layer flow past a Riga plate with variable thickness using generalized Fourier’s law

Abstract This article explores the problem of two-dimensional, laminar, steady and boundary layer stagnation point slip flow over a Riga plate. The incompressible upper-convected Maxwell fluid has been considered as a rheological fluid model. The heat transfer characteristics are investigated with generalized Fourier’s law. The fluid thermal conductivity is assumed to be temperature dependent in this study. A system of partial differential equations governing the flow of an upper-convected Maxwell fluid, heat and mass transfer using generalized Fourier’s law is developed. The main objective of the article is to inspect the impacts of pertinent physical parameters such as the stretching ratio parameter ( 0 ⩽ A ⩽ 0.3 ) , Deborah number ( 0 ⩽ β ⩽ 0.6 ) , thermal relaxation parameter ( 0 ⩽ γ ⩽ 0.5 ) , wall thickness parameter ( 0.1 ⩽ α ⩽ 3.5 ) , slip parameter ( 0 ⩽ R ⩽ 1.5 ) , thermal conductivity parameter ( 0.1 ⩽ δ ⩽ 1.0 ) and modified Hartmann number ( 0 ⩽ Q ⩽ 3 ) on the velocity and temperature profiles. Suitable local similarity transformations have been used to get a system of non-linear ODEs from the governing PDEs. The numerical solutions for the dimensionless velocity and temperature distributions have been achieved by employing an effective numerical method called the shooting method. It is seen that the velocity profile shows the reduction in the velocity for the higher values of viscoelastic parameter and the thermal relaxation parameter. In addition, to enhance the reliability at the maximum level of the obtained numerical results by shooting method, a MATLAB built-in solver bvp4c has also been utilized.

Inspiration of slip effects on electromagnetohydrodynamics (EMHD) nanofluid flow through a horizontal Riga plate

The boundary layer flow of nanofluid that is electrically conducting over a Riga plate is considered. The Riga plate is an electromagnetic actuator which comprises a spanwise adjusted cluster of substituting terminal and lasting magnets mounted on a plane surface. The numerical model fuses the Brownian motion and the thermophoresis impacts because of the nanofluid and the Grinberg term for the wall parallel Lorentz force due to the Riga plate in the presence of slip effects. The numerical solution of the problem is presented using the shooting method. The novelties of all the physical parameters such as modified Hartmann number, Richardson number, nanoparticle concentration flux parameter, Prandtl number, Lewis number, thermophoresis parameter, Brownian motion parameter and slip parameter are demonstrated graphically. Numerical values of reduced Nusselt number, Sherwood number are discussed in detail.

Aiding and opposing mixed convection flows over the Riga-plate

The Blasius flow of an electrically conducting fluid over the Riga-plate is considered. The Riga-plate is an electromagnetic actuator which consists of a spanwise aligned array of alternating electrodes and permanent magnets mounted on a plane surface. This array generates a surface-parallel Lorentz force which decreases exponentially in the direction normal to the plate. The governing parameter of the title problem is the modified Hartmann number Z, which is positive when the Lorentz points in the direction of the free stream ( aiding flow) and negative when it is opposite to the free stream ( opposing flow). The characteristics of physical and engineering interest of these doubly driven aiding and opposing mixed convection flows are discussed in the paper in detail.

Electromagnetically induced chaotic mixing in a pipe mixer

A numerical investigation is carried out to study the mixing by chaotic advection in an electromagnetically driven pipe mixer. It consists of a pipe with two inner electrodes which are energized alternatively. An externally applied magnetic field along the flow direction interacts with the local electric currents inducing a spatially varying electromagnetic body force in the model fluid. The system is an extension of Aref's blinking vortex model to three dimensions. The Lagrangian motion of passive tracer particles is numerically simulated to quantify the degree of stirring. The model predictions indicate that the chaotic mixing is strongly dependent on the modified Hartmann number, the electrode switching frequency and the electrode separation distance. A comparison with numerical simulation results obtained using a dimensional model with glass melt shows that the chaotic mixing behavior of the glass melt is very close to the non-dimensional model predictions. The computational results presented here will be useful for developing efficient glass melt homogenisation systems.