MHD (Fluid Dynamics)

Unsteady-state free convection heat transfer in an equilateral triangular cavity, filled with a fluid-saturated porous medium and with heat generation in presence of magnetic field has been considered in this study. The horizontal wall of the cavity is heated at a constant temperature, the left inclined wall is non-isothermal and the right inclined wall is differentially cold. The governing equations are solved numerically by finite element method. The effect of MHD and heat generation on the streamlines and isotherms are investigated for the fluid of Prandtl number (Pr = 0.7) and Rayleigh number (Ra = 1e5). The average temperature of the cavity and the rate of heat transfer of the bottom surface of the cavity are also presented.

In this paper unsteady magnetohydrodynamic convection has been analyzed using numerical and statistical techniques for a semicircular-shaped enclosure filled with ferrofluid. Cobalt–kerosene ferrofluid is considered for the present investigation. Galerkin weighted residuals method of finite element ananlysis is adopted for the numerical simulation. The effects of Rayleigh number (Ra), solid volume fraction (ϕ) of ferrofluid and Hartmann number (Ha) are considered as pertinent parameters and varied for a wide range of values (Ra = 10^5–10^7, ϕ = 0–0.15, Ha = 0–50) to capture the flow and thermal interaction phenomena for unsteady situation. It is observed that higher ferrofluid solid volume fraction escalates the heat transfer rate. Enhancing the intensity of external magnetic field (by increasing Ha) retards the heat transfer rate while increment of Ra exhibits improvement on the heat transfer. It is also found that there exists a strong interacion between ferromagnetic particle (cobalt) and base fluid (kerosene) in the presence of magnetic field which can be utilized properly for desired heat transfer augmentation. If ϕ = 0 (or ϕ = 0.15) and Ra is changed from 105 to 107, the linear dependence of Ψmax on time changes significantly from positive to negative.

The Navier-Stokes differential equations describe the motion of fluids which are incompressible. The three-dimensional Navier-Stokes equations misbehave very badly although they are relatively simple-looking. The solutions could wind up being extremely unstable even with nice, smooth, reasonably harmless initial conditions. A mathematical understanding of the outrageous behaviour of these equations would dramatically alter the
field of fluid mechanics. This paper describes why the three-dimensional Navier-Stokes equations are not solvable, i.e., the equations cannot be used to model turbulence, which is
a three-dimensional phenomenon.

The present is a research proposal to evaluate the possibility of desalinate water using a unique approach. According to the present study desalination is achieved using magnetohydrodynamic (MHD) means, more specifically through dynamo effect. And the corresponding reuse of the energy gain obtained from the process.

This study intends to elaborate the heat and mass transfer analysis of Casson nanofluid flow past a stretching sheet together with magnetohydrodynamics (MHD), thermal radiation and chemical reaction effects. The boundary layer approximations established the governing equations, i.e., time-subservient momentum, energy and diffusion balance equations. An explicit finite difference scheme was implemented as a numerical technique where Compaq Visual Fortran 6.6.a programming code is also developed for simulating the fluid flow system. In order to accurateness of the numerical technique, a stability and convergence analysis was carried out where the system was found converged at Prandtl number, Pr ! 0.062 and Lewis number, Le ! 0.025 when s = 0.0005, DX = 0.8 and DY = 0.2. The non-dimensional outcomes are apprehended here which rely on various physical parameters. The impression of these various physical parameters on momentum and thermal boundary layers along with concentration profiles are discussed and displayed graphically. In addition, the impact of system parameters on Cf, Nu and Sh profiles with streamlines and isothermal lines are also discussed.

This work reports an analytical solution for a steady and fully developed natural convection flow of viscous, incompressible, electrically conducting fluid in a vertical micro-porous-annulus under the influence of a radial magnetic field by taking in to consideration of velocity slip and temperature jump at the vertical micro-porous-annulus (MPA) surfaces. A closed-form solution is presented for velocity, temperature, volume flow rate, skin-friction and the rate of heat transfer which is expressed in terms of a Nusselt number. The influence of each governing parameter such as Hartmann number, suction/injection, Prandtl number, rarefaction, fluid-wall interaction and curvature radius ratio on hydrodynamic and thermal behaviour is shown graphically. During the course of investigation, it is found that as Hartmann number increases, the fluid velocity decreases. Furthermore, an increase in Hartmann number leads to a decrease in the volume flow rate.

An exact solution of steady fully developed mixed convection flow of vis-cous, incompressible, electrically conducting fluid in a vertical microannulus in the presence of transverse magnetic field by taking in to consideration of velocity slip and temperature jump at the vertical microannulus surfaces is obtained. The momentum and energy equations representing the present physical situation are presented in dimensionless form along with relevant boundary conditions. The mathematical model is solved using the method of undetermined coefficients. Exact solution is expressed in terms of modified Bessel function of first kind and second kind. The solution obtained is graphically represented and the effects of radius ratio, magnetic field, Knudsen number, and mixed convection on the flow is investigated. It is interesting to remark that as magnetic field increases, there is decrease in the fluid velocity at the outer surface of inner cylinder while there is an increase at the inner surface of the outer cylinder. Furthermore, it is also discovered that an increase in magnetic field parameter leads to decrease in the rate of heat transfer at outer surface of inner cylinder while it increase at inner surface of outer cylinder.

Purpose-The purpose of this paper is to present an exploration of multiple slips and temperature dependent thermal conductivity effects on the flow of nano Williamson fluid over a slendering stretching plate in the presence of Joule and viscous heating aspects. The effectiveness of nanoparticles is deliberated by considering Brownian moment and thermophoresis slip mechanisms. The effects of magnetism and radiative heat are also deployed. Design/methodology/approach-The governing partial differential equations are non-dimensionalized and reduced to multi-degree ordinary differential equations via suitable similarity variables. The subsequent non-linear problem treated for numerical results. To measure the amount of increase/decrease in skin friction coefficient, Nusselt number and Sherwood number, the slope of linear regression line through the data points are calculated. Statistical approach is implemented to analyze the heat transfer rate. Findings-The results show that temperature distribution across the flow decreases with thermal conductivity parameter. The maximum friction factor is ascertained at stronger magnetic field. Originality/value-In the current paper, the magneto-nano Williamson fluid flow inspired by a stretching sheet of variable thickness is examined numerically. The rationale of the present study is to generalize the studies of Mebarek-Oudina and Makinde (2018) and Williamson (1929).

In this study, we examine the combined effects of
thermal radiation, chemical reaction on MHD hydromagnetic
boundary layer flow over a vertical cone filled with nanofluid
saturated porous medium under variable properties. The
governing flow, heat and mass transfer equations are
transformed into ordinary differential equations using similarity
variables and are solved numerically by a Galerkin Finite
element method. Numerical results are obtained for
dimensionless velocity, temperature, nanoparticle volume
fraction, as well as the skin friction, local Nusselt and Sherwood
number for the different values of the pertinent parameters
entered into the problem. The effects of various controlling
parameters on these quantities are investigated. Pertinent
results are presented graphically and discussed quantitatively.
The present results are compared with existing results and found
to be good agreement. It is found that the temperature of the
fluid remarkably enhances with the rising values of Brownian
motion parameter (Nb).

Purpose – The purpose of this paper is to examine the combined effects of thermal radiation and magnetic field of molybdenum disulfide nanofluid in a channel with changing walls. Water is considered as a Newtonian fluid and treated as a base fluid and MoS2 as nanoparticles with different shapes (spherical, cylindrical and laminar). The main structures of partial differential equations are taken in the form of continuity, momentum and energy equations. Design/methodology/approach – The governing partial differential equations are converted into a set of nonlinear ordinary differential equations by applying a suitable similarity transformation and then solved numerically via a three-stage Lobatto III-A formula. Findings – All obtained unknown functions are discussed in detail after plotting the numerical results against different arising physical parameters. The validations of numerical results have been taken into account with other works reported in literature and are found to be in an excellent agreement. The study reveals that the Nusselt number increases by increasing the solid volume fraction for different shapes of nanoparticles, and an increase in the values of wall expansion ratio α increases the velocity profile f′(η) from lower wall to the center of the channel and decreases afterwards. Originality/value – In this paper, a numerical method was utilized to investigate the influence of molybdenum disulfide (MoS2) nanoparticles shapes on MHD flow of nanofluid in a channel. The validity of the literature review cited above ensures that the current study has never been reported before and it is quite new; therefore, in case of validity of the results, a three-stage Lobattoo III-A formula is implemented in Matlab 15 by built in routine “bvp4c,” and it is found to be in an excellent agreement with the literature published before.

This study exhibited the investigation of magnetohydrodynamics (MHD) boundary layer phenomenon of Casson and Williamson nanofluids, which was flowing on an inclined cylindrical surface. The impact of linear order chemical reaction with thermal radiation had been considered in multiphase flows. By taking the assistance of compact visual FORTRAN 6.6a programming algorithm, the finite scheme was imposed explicitly for attaining the dimensionless form of the fundamental equations. The convergence criterion had also been established for the exactness of the pertinent parameters. It was observed that the ongoing work converged for Lewis number 0.036 Le ≥ and Prandtl number Pr 0.52 ≥. A tabular comparison had been presented to validate the numerical modelling, and a favourable result was attained. The obtained outcomes were analysed for diversified pertinent parameters on different flow fields. Besides, the influence of Casson and Williamson parameters were also displayed through streamlines and isotherms. However, this study investigated the fluid behavior of Lorentz force effects together with Nano-particle which increase the thermal conductivity of both fluids. The study has been done in two different phase of fluid flows. Finally, it was concluded that the mass and heat transform accomplishment of Williamson fluid was relatively lower compared to Casson fluid. The comparison was also done significantly through the updated visualisation of fluid flow in this study.

La magnetohidrodinámica es la teoría que describe la dinámica de un fluido conductor en presencia de un campo electromagnético, especialmente cuando las corrientes establecidas en el fluido por inducción, modifican el campo. En hidrodinámica generalmente se trata el fluido como un medio isotrópico; es decir, el fluido no presenta una preferencia direccional en el espacio y se comporta de igual forma en cualquier dirección. En MHD al tratarse de un fluido que interactúa con el campo magnético es más complejo el fenómeno, debido a que este si presenta una dirección preferencial espacial, por lo que el fluido magnetizado debe tratarse como un medio anisotrópico. Ya que existe una interacción entre el fluido y el campo magnético, se deben acoplar las ecuaciones de Maxwell con las ecuaciones dinámicas del fluido. Aproximación MHD ideal: 1. Aproximación de fluido: las cantidades termodinámicas locales pueden ser definidas de manera significativa en el plasma, y las variaciones en estas cantidades son pequeñas comparadas con la escala de tiempo de los procesos microscópicos en el plasma. 2. En el plasma, existe una relación local instantánea entre el campo eléctrico y la densidad de corriente; es decir, se cumple la Ley de Ohm 3. Se asume una alta conductividad eléctrica, lo cual previene la separación de las cargas eléctricas y por lo tanto la generación de un campo eléctrico. Por lo tanto, esto implica que los campos eléctricos resultantes son pequeños comparados con los campos magnéticos (Cuasi-neutralidad). Es decir, la densidad de energía magnética es mucho mayor que la densidad de energía eléctrica.

The irreversibility in convective nanofluid flow in the occurrence of a magnetic field (MHD) in a cavity with chamfers is calculated by numerical approach. The nanofluid flow is considered under the impacts of magnetic field and thermal gradient. The continuity, motion and energy equations are solved by applying COMSOL Multiphysics computer package. The impacts of (Ha) Hartmann number, () elevation of magnetic field, nanoparticle volume fraction, heat transmission and entropy analysis on the flow of nanofluid are discussed. Results reveal that, the impacts of volume fraction and the magnetic force on different irreversibility are significant. Moreover, results indicate the existence of a critical (Ha c) Hartmann number this represents the frontier between the domains where the magnetic field dominates via its intrinsic effect and its extrinsic effect.

This study intends to elaborate the heat and mass transfer analysis of Casson nanofluid flow past a stretching sheet together with magnetohydrodynamics (MHD), thermal radiation and chemical reaction effects. The boundary layer approximations established the governing equations, i.e., time-subservient momentum, energy and diffusion balance equations. An explicit finite difference scheme was implemented as a numerical technique where Compaq Visual Fortran 6.6.a programming code is also developed for simulating the fluid flow system. In order to accurateness of the numerical technique, a stability and convergence analysis was carried out where the system was found converged at Prandtl number, Pr ! 0.062 and Lewis number, Le ! 0.025 when s = 0.0005, DX = 0.8 and DY = 0.2. The non-dimensional outcomes are apprehended here which rely on various physical parameters. The impression of these various physical parameters on momentum and thermal boundary layers along with concentration profiles are discussed and displayed graphically. In addition, the impact of system parameters on Cf, Nu and Sh profiles with streamlines and isothermal lines are also discussed.

The present paper investigates the effect of linear thermal stratification in stable stationary ambient fluid on steady MHD convective flow of a viscous incompressible electrically conducting fluid along a stretching sheet in the presence of mass transfer and magnetic effect. The governing equations of
continuity, momentum, energy and species are transformed into ordinary differential equations using local similarity transformation. The resulting coupled non-linear ordinary differential equations are solved using Runge-Kutta fourth order method along with shooting technique. The
velocity, temperature and concentration distributions are discussed numerically and presented through graphs. The numerical values of skin-friction coefficient, Nusselt number and Sherwood number at the plate are derived and discussed numerically for various values of physical parameters
which are presented through tables

In general, magnetite (Fe 3 O 4) nanoparticles move randomly within the base fluid. By applying an external magnetic field, the movement of those nanoparti-cles becomes homogeneous. This is very useful in heat transfer processes. In addition, applied magnetic fields are capable to set the thermal and physical natures of the nanofluids with magnetic properties. The heat and mass transfers of non-Newtonian fluids play a major role in technology and in nature due to its stress relaxation, shear thinning, and thickening properties. With this incentive, we investigate the momentum, thermal, and concentration boundary layer behavior of liquid-film flow of water-based non-Newtonian nanofluids dispensed with magnetite nanoparticles. For this investigation, we propose a mathematical model, which deals with the flow of Jeffrey and Oldroyd-B nanofluids past a stretched plate with transverse magnetic field, space and temperature-dependent heat source/sink, thermophoresis, and Brownian movement effects. Numerical results are carried out by employing the Runge–Kutta and Newton's methods. The influence of pertinent parameters on common profiles (velocity, temperature , and concentration) along with the reduced Nusselt number is presented graphically. It is found that suspending the magnetite nanoparticles effectively enhances the thermal conductivity of the Jeffrey nanofluid when compared with the Oldroyd-B nanofluid. Keywords Brownian movement Á Magnetite nanoparticles Á MHD Á Liquid-film flow Á Space-and temperature-dependent heat source/sink Á Thermophoresis

An investigation is carried out to analyze the unsteady MHD free convection, heat and mass transfer flow of a Newtonian fluid past an infinite
vertical porous plate with homogeneous chemical reaction and heat absorption/generation. A uniform magnetic field is applied perpendicular to the
plate. The non-dimensional governing equations are solved numerically by using finite difference method. The effects of various parameters
governing the flow on velocity, temperature, concentration, skin friction, Nusselt number and Sherwood number are studied through graphs. It is
noticed that velocity decreases with an increase in Magnetic field while it increases with an increase in Grashof number, modified Grashof number&
Permeability parameter. Temperature increases with an increase in heat absorption and it shows reverse effect in the case of heat generation and
Prandtl number. Concentration decreases with increase in Schmidt number and chemical reaction parameter.

In this article, flow and heat transfer effects of both single and multiple wall carbon nanotubes within the base fluid (water) are analyzed between two rotating plates. Moreover, we have considered that the upper wall of the channel is permeable while the lower wall is moving with variable velocity to produce the forced convection along with the Coriolis and centripetal forces with the rotation of fluid. The compatible transformations have been used to construct the non-dimensional system of governing equations. Numerical simulation is performed to obtain the solutions structure. Thermophysical properties of each base fluid and nano particle are incorporated in the form of thermal conductivity, viscosity, density, specific heat, nanoparticle volume fraction and Prandtl number to attain the solution of the model. It is found that water based single wall carbon nanotubes (SWCNTs) produce less drag and high heat transfer rate as compared to the water based multiple wall carbon nanotubes (MWCNTs). Influence of rotation causes the drag increase and decreases the Nusselt number irrespective of the other pertinent parameters. Moreover suction/injection plays an important role in determining the peak position of velocity. The effect of suction/injection is shown through plotting streamlines.

A mathematical framework has been designed to speculate the physical aspects of a binary chemical reaction (BCR) and Arrhenius activation energy (ACE) on magnetohydrodynamics Williamson micropolar nanofluid flow through a vertical stretching sheet. The fluid viscosity, electrical and thermal conductivity are presumed as reliant temperature function. Furthermore, the Lorentz force is deployed with an angle to the normal of the fluid flow. The natural transformations have been chosen to determine the non-dimensional regular expressions of the model. A conditionally stable finite difference analysis (explicit) is implemented to establish the computational analysis of the transfigured non-linear system of PDEs. The precision of the present numerical solution has been enriched by accomplishing analysis of stability as well as system convergence of finite difference analysis. The graphical representation, along with the tabular depiction, has been done for narrating the physical behaviour of important parameters extensively on various flow fields. The fluctuation of the boundary layer thickness is traced out with the assistance of streamlines, isotherms, and iso-concentration for the impression of the buoyancy ratio parameter and Lewis number. To draw perfection, achieved consequences of the current solution have been contrasted with some subsisting literature.

A boundary-layer analysis is presented for the magnetohydrodynamic (MHD) forced convection flow of a nanofluid adjacent to a non-isothermal wedge. The model used for the nanofluid incorporates the effects of Brownian motion and thermophoresis. The governing partial differential equations are transformed into a set of non-similar equations and solved numerically by an efficient implicit, iterative, finite-difference method. Comparisons with previously published work are performed and excellent agreement is obtained. A parametric study of the physical parameters is conducted and a representative set of numerical results for the velocity, temperature, and nanoparticles volume fraction profiles as well as the local skin-friction coefficient and local Nusselt and Sherwood numbers are illustrated graphically to show interesting features of the solutions.

The transfer equations of anisotropic solar wind, referring to the MHD theory, were applied in the study, taking into account the difference between the heat fluxes and heat pressures between parallel and vertical. It is assumed that the anisotropy is due to the magnetic field. For a stationary state in a spherical coordinate system, the equations obtained only for the case of radial dependence include the components of solar wind speed (X), parallel (Y) and perpendicular (Z) heat velocities, as well as constants obtained during transformations (C5, C6). Since the general solution of the equations is not yet possible, research has been conducted to determine the specific solutions. The quantities X, Y, and Z are considered to depend only on the radial distance for simplicity. Previous studies have examined the solution of a system of equations based on different relationships between Y and X. In this work, it was possible to find several more special solutions to the system of equations consisting of three differential expressions by means of various substitutions and approximations that simplify the equations. Some special solutions for MHD transport equations for single-particle liquid plasma of anisotropic solar wind have been found. The solutions can characterize the points after the number Max. But it is not a general solution. The specific solutions give an idea of the radial dependence of the solar wind speed, and the solutions are important in the wider study of solar wind, in the study of single-particle state and MHD theory, as well as in studying the properties, parameters and geometric dimensions of heliosphere and cosmic star wind.

Present model is devoted for the stagnation point flow of nanofluid with magneto-hydrodynamics (MHD) and thermal radiation effects passed over a stretching sheet. Moreover, we have considered the combined effects of velocity and thermal slip. Condition of zero normal flux of nanoparticles at the wall for the stretched flow phenomena is yet to be explored in the literature. Convinced partial differential equations of the model are transformed into the system of coupled nonlinear differential equations and then solved numerically. Graphical results are plotted for velocity, temperature and nanoparticle concentration for various values of emerging parameters. Variation of stream lines, skin friction coefficient, local Nusselt and Sherwood number are displayed along with the effective parameters. Final conclusion has been drawn on the basis of both numerical and graphs results.

The objective of present problem is to investigate the effects of thermal diffusion, viscous dissipation, radiation and chemical reaction on a well-known non Newtonian fluid namely Kuvshinski fluid interaction on unsteady MHD flow over a vertical moving porous plate. The fluid is considered to be a gray, absorbing emitting but non scattering medium, and the Rosseland approximation is used to describe the radiative heat flux energy equation. The plate moves with constant velocity in the direction of fluid flow while the free stream velocity is assumed to follow the exponentially increasing small perturbation law. A uniform magnetic field acts perpendicular to the porous surface. The dimensionless governing equations are solved by using a simple perturbation law. The expressions for velocity, temperature and concentration are derived. With the aid of these the expressions for Skin friction, Nusselt number and Sherwood number are also derived. The effects of various material parameters on the above flow quantities are studied numerically with the help of figures and tables. It is observed that an increases in the Prandtl number results in a decreasing in temperature. An increase in Kr leads to decrease in both of concentration and velocity.

Magnetohydrodynamic micropumps received more attention due to its applications in pumping of biological and chemical specimens, such as blood, DNA, and saline buffers. In this paper the MHD flow in different cross section microchannels has been numerically investigated with different electromagnetic boundary conditions. Square, rectangular, circular and trapezoidal cross section microchannels have been used to explore the effect of channel geometry on the MHD micropump operation. The study covers a selected range of applied electric currents and magnetic flux to show their effects on MHD flow. Thermal characteristics of MHD flow have been also studied by calculation the temperature distribution through MHD micropump region. The results obtained show a considerable effect of channel geometry, the applied electric and magnetic fields on the velocity and flow rate. The circular cross section microp-ump gave higher velocity and flow rate compared with other cross sections, and there is a slight increase in temperature due to small effect of Joule heating.

The present analysis emphasizes the effects of variable properties on Bingham fluid under MHD peristaltic transport. Due to the impact of mechanical forces on the applied magnetic field on the conducting fluid, the fluid stream gets altered. These principle targets drug transport and control of blood flow during surgeries; hence the impact of MHD flow with convective and porous boundary conditions is considered. Further, the implications of homogeneous and heterogeneous reactions are analyzed by considering wall properties. The governing equations are turned dimensionless by appropriate similarity transformations. The series solution is obtained for temperature, velocity, and concentration by perturbation method with lubrication approach. The graphical representation of the pertinent parameters on the physiological flow quantities is depicted by applying for MATLAB 2019b program. The obtained results reveal that the rise in the magnetic parameter diminishes the velocity and temperature profiles. Further, the impact of variable viscosity slightly improves the magnitude of the trapped bolus. The homogenous and heterogeneous reaction parameters have a converse effect on the concentration distribution. Moreover, the present investigation finds its applications to perceive the complex rheological functioning of blood flow through narrow arteries.

An analytical solution is investigated for a fully developed free convective flow of a visco-elastic incompressible
electrically conducting fluid past a vertical porous plate bounded by a porous medium in the presence of thermal
diffusion, variable suction and variable permeability. A magnetic field of uniform strength is applied perpendicular to
the plate and the presence of heat source is also considered. The novelty of the study is to investigate the effect
of thermal diffusion on a visco-elastic fluid in the presence of time dependent variable suction. The importance
is due to the applications of this kind of visco-elastic fluids in many industries. The coupled dimensionless nonlinear
partial differential equations are transformed into a set of ordinary differential equations by using multiple
parameter perturbation on velocity whereas simple perturbation method on temperature and concentration. With
corresponds to these, the expressions for skin friction, Nusselt number and Sherwood number are derived. The
numerical computations have been studied through figures and tables. The presence of thermal diffusion increases
fluid velocity, whereas the influence of the magnetic field reduces it. In the case of heavier species, it is noticed that
concentration increases with an increase in Soret number.

The dynamics of unsteady magnetohydrodynamics convective fluid flow with radiation and thermophoresis of particles past a vertical porous plate moving through a binary mixture in an optically thin environment is investigated. The approximate form of the radiative heat flux is considered as the fourth power of temperature. Chemical reaction that occurs as the chemically reacting fluid flow through binary mixture is accounted for in energy and species concentration equations. Exponential space dependent heat source is introduced to generate additional heat energy across the fluid domain. The corresponding influence of heat energy is properly accounted for. It is assumed that viscosity and thermal conductivity vary as a linear function of temperature. The governing boundary layer equations are converted to nonlinear ordinary differential equations using similarity variables. A novel method of obtaining root finding starting with three guesses in shooting techniques is presented. The corresponding nonlinear coupled ordinary differential equations is solved numerically by shooting technique along with quadratic interpolation scheme. Graphical results of the dimensionless velocity, temperature and concentration distributions are shown for certain pertinent parameters controlling the fluid flow. The quadratic interpolation method is found to produce better estimated values of f''(0), -theta'(0), and -phi(0) which satisfy the degree of accuracy and proportional to the physical quantities.

Purpose – The purpose of this paper is to comprehensively review most of the significant works ever done worldwide to study the effects of essential parameters on PPT Performance and to analyze the effects of each parameter on PPT performance.

Design/methodology/approach – All the important works studying PPT performance are categorized by the parameter they have studied its effect on the thruster performance and their works have been reviewed to analyze the influence of each parameter.

Findings – The analysis leads to elucidate the effects of different geometrical parameter including aspect ratio, electrode
Width, electrode spacing, electrode shape, electrode length, and flare angle in addition to the effects of other parameters like electrode material, propellant type, propellant temperature, Spark distance from propellant, pulse repetition frequency, discharge energy, capacitance, and hood angle on PPT performance.

Research limitations/implications – The analysis is mainly focused on parallel-rail breech-fed PPTs and side-fed PPTs and does not deal with co-axial PPTs.

Originality/value – The current paper reviews and analyses many of the considerable works ever done to contribute to clarify the effects of different parameters on PPT performance. The results of the current analysis can be an invaluable assistance in PPT design and optimization procedure and helps the designer to develop a system with better performance characteristics.

Convection in a laterally heated three-dimensional box affected by a strong magnetic field is
considered in the quasi-two-dimensional Q2D formulation. It is assumed that the magnetic field is
strong and is normal to the main convective circulation. The stability of the resulting Q2D flow is
studied for two values of the Hartmann number scaled by half of the width ratio, 100 and 1000, and
for either thermally insulating or perfectly conducting horizontal boundaries. The aspect
length-to-height ratio of the box is varied continuously between 4 and 10. It is shown that the
magnetic field damps the bulk flow and creates thermal and Shercliff boundary layers at the
boundaries, which become the main source of instabilities. In spite of the general tendency of the
flow stabilization by the magnetic field, the flow instability takes place in different ways depending
on the boundary conditions and the aspect ratio. Similarities with other magnetic field directions and
flows with larger Prandtl numbers are discussed.

Purpose-Metal-cooled reactors generally use molten metals such as sodium, potassium or a combination of sodium and potassium because of their excellent heat transfer properties so that the reactor can operate at much lower pressures and higher temperatures. The purpose of this paper is to investigate the stability of natural convection in an inclined ring filled with molten potassium under the influence of a radial magnetism. Design/methodology/approach-A numerical simulation of electrically conductive fluid natural convection stability is performed on an inclined cylindrical annulus under the influence of a radial magnetism. The upper and lower walls are adiabatic, while the internal and external cylinders are kept at even temperatures. The equations governing this fluid system are solved numerically using finite volume method. The SIMPLER algorithm is used for pressure-speed coupling in the momentum equation. Findings-Numerical results for various effective parameters that solve the problem in the initial oscillatory state are discussed in terms of isobars, isotherms and flow lines in the annulus for a wide range of Hartmann numbers (0 # Ha # 80), inclination angles (0 # g # 90°) and radii ratios l # 6. The dependency stability diagrams between complicated situations with the critical value of the Rayleigh number RaCr and the corresponding frequency FrCr are established on the basis of the numeric data of this investigation. The angle of inclination and the radii ratio of the annulus have a significant effect on the stabilization of the magneto-convective flux and show that the best stabilization of the natural oscillatory convection is obtained by the intensity of the strongest magnetic field, the high radii ratio and inclination of the annulus at g = 30°.