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In this paper, heat transfer in a sinusoidal channel filled with nanofluid under magnetic field effect is investigated numerically. The magnetic field transversely applied to the channel. Water as a base fluid and copper as nano particles were considered .The Maxwell-Garnetts model and Brinkman model for heat conduction coefficient and dynamic viscosity were used respectively. The effects of changing some parameters such as shape ,volume fraction , Hartmann number and Reynods number were considered. The results show that increasing in all mentioned parameters lead to increasing in Nusselt number. Volume fraction is mainly affect on maximum local Nusselt number in each channel’s wave while Hartmann number is affected minimum and maximum Nusselt number.

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In this study, a two-dimensional, axisymmetric, computational Algorithm has been developed to simulate the plasma flowfield in a MPD thruster for the purpose of determining the flow behavior and electromagnetic characteristics distribution. The solution employs Roe’s flux vector difference method in combination with Powell’s characteristics-splitting scheme. To ensure the stable high-accuracy solution, new modification of MUSCL technique so called OMUSCL2 method is used. According to being supersonic strong gasdynamic expansion near the electrodes tip, HHT entropy correction is employed. Further improvements to the physical model, such as the inclusion of relevant classical transport properties, a real equation of state, multi-level equilibrium ionization models, anomalous transport, and multi-temperature effects, that are essential for the realistic simulation MPD flows, are implemented. Numerical results of a lab-scale thruster are presented, whereby comparison with experimental data shows good agreement between the predicted and measured enclosed current and electric potential.

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In this work, A 3-dimensional model is developed to investigate fluid flow in a magneto-hydrodynamic micropump. The equations are numerically solved using the finite volume method and the SIMPLE algorithm. This study analyzes the performance of the magnetohydrodynamic micropump. For this purpose, a magnetohydrodynamic micropump built in 2000, is simulated. The micropump has a channel with 20mm length, width of 800 , height of 380 and an electrode with 4mm length. The applied magnetic flux density was 13mT and the electric current was different for various solution (10-140 mA). The results show that the intensity of the magnetic field, the electric current and the geometry has an effect on the magnetohyrodynamic micropump performance. By increasing the amount of magnetic flux and electric current the average velocity increases. decreasing the channel length would increase the mean flow velocity. by increasing the channel depth, the mean flow velocity initially increases and then decreases, while at a depth of approximately 700-800 the maximum averaged velocity will be resulted. The velocity increases by Increasing the channel width to 1500 , however the velocity remained unchanged for larger values.

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This Study presents a numerical investigation of the hydro-thermal behavior of a Non-Newtonian ferrofluid (non-Newtonian base fluid and 4% Vol. Fe3O4) in a rectangular vertical duct in the presence of different magnetic fields, using two-phase mixture model, power-law model, and control volume technique. Considering the electrical conductivity of the base fluid, in addition to the ferrohydrodynamics principles, the magnetohydrodynamics principles have also been taken into account. To study the effects of non-Newtonian base fluid using power-law model, assuming the same flow consistency index with viscosity of Newtonian fluid, two different power law indexes (i.e., n=0.8 and 0.6), have been investigated and the results have been compared with that of Newtonian ones (i.e., n=1). Three cases for magnetic field have been considered to study mixed convection of the ferrofluid: non-uniform axial field, uniform transverse field and another case when both fields are applied simultaneously. The results indicate that the overall influence of magnetic fields on Nusselt number and friction factor is similar to the Newtonian case, although, by decreasing the power law index, the effect of axial field on velocity profile, Nusselt number and friction factor become more significant. Moreover, the results indicate that electrical conductivity has a significant effect on the behavior of ferrofluid and cannot be neglected and also negative gradient axial field and uniform transverse field act similarly and enhance both the Nusselt number and the friction factor, while positive gradient axial field decreases them.

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This study attempts to numerically investigate the hydro-thermal characteristics of a ferrofluid (water and 4 vol% ) in a counter-current horizontal double pipe heat exchanger, which is exposed to a non-uniform transverse magnetic field with different intensities. The magnetic field is generated by an electric current going through a wire parallelly located close to the inner tube and between two pipes. The single phase model and the control volume technique have been used to study the flow. The effects of magnetic field has been added to momentum equation by applying C++ codes in Ansys Fluent 14. The results show that applying this kind of magnetic field causes to produce kelvin force perpendicular to the ferrofluid flow changing axial velocity profile and creating a pair of vortices leads to increase the Nusselt number, friction factor and pressure drop. Comparing the enhancement percentage of Nusselt number, friction factor and pressure drop demonstrate that the optimum value of magnetic number for Re_ff=50 is between Mn=1.33*10^6 and Mn=2.37*10^6 So applying non-uniform transverse magnetic field can control the flow of ferrofluid and improve heat transfer process of double pipe heat exchanger.

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Peristaltic phenomenon is widely used for biologically tissues such as the digestive and excretion of urine systems. Fingered and roller pumps, hoses and internal pumps, pumps for waste management in the nuclear industry are also working on the wavy walls rules. Hence, in this paper, the magnetic hydrodynamic flow of nanofluids inside a curved porous channel, with peristaltic walls and within the internal heat source has been studied. In the present study, the flow is incompressible and the governing equations, including flow, heat and mass transfer are obtained by using an assumption of long wavelength. For solving the equations, the central finite difference approximation algorithm and Keller-box method are utilized. Heat transfer is reduced due to the presence of a magnetic field. Also, increasing the power of the heat source and the Darcy number reduces the heat transfer. Increasing porosity in the environment increases the heat transfer. Increasing the power of the heat source is accompanied by a reduction in velocity in the central line of the channel in the corrugated mode.
In this paper, by using the numerical solution results, the effect of various parameters such as source term, Darcy number and porosity on the velocity, distribution of temperature, the function of the magnetic force, increase the pressure on the wavelength, Nusselt number and also the flow trapping phenomenon has been studied.

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In the present study, the instability in the interface of two semi-infinite fluid layers with applying a shock is studied. To this end, the effect of various parameters such as fluid densities, velocities of fluids, and magnetic field on the instability is explored. By using the magneto-hydrodynamic equations, a general equation is developed for the evolution of perturbation amplitude near the interface. Analytical and graphical results indicate that the time dependent part of perturbation amplitude is the same for both the constant and varying density cases and the instability depends on the growth rate. Remarkably, the growth rate depends on the characteristics of the fluids and magnetic field and can be real or imaginary; hence, the stability condition is determined with respect to this parameter. Furthermore, it is shown that the spatial part of the perturbation amplitude in the constant density case, even with different densities, is symmetric and independent from the layer densities and damps exponentially in the two sides of the interface. On the other hand, it is shown that in the varying density case, the function of the spatial part of the perturbation amplitude depends on the parameters of the environment and the fluid; so the spatial part of the perturbation amplitude in the two fluid damps asymmetrically. Moreover, the results attained in the constant density case match the findings of the previous studies.