Topic
Hartmann number
About: Hartmann number is a(n) research topic. Over the lifetime, 2593 publication(s) have been published within this topic receiving 61342 citation(s).
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TL;DR: In this paper, the effects of Brownian motion on the effective viscosity and thermal conductivity of nanofluid were investigated. And the results were presented graphically in terms of streamlines, isotherms and isokinetic energy.
Abstract: In this paper magnetohydrodynamics nanofluid hydrothermal treatment in a cubic cavity heated from below is presented. The mathematical model consists of continuity and the momentum equations, while a new model is proposed to see the effects Brownian motion on the effective viscosity and thermal conductivity of nanofluid. The Lattice Boltzmann method is utilized to simulate three dimensional problems. The Koo–Kleinstreuer–Li correlation is also taken into account. Numerical calculation is made for different values of Hartmann number, nanoparticle volume fraction and Rayleigh number. The results are presented graphically in terms of streamlines, isotherms and isokinetic energy as well as Nusselt number. It is observed that the applying magnetic field results in a force opposite to the flow direction that leads to drag the flow and then reduces the convection currents by reducing the velocities. Also it can be concluded that Nusselt number is an increasing function of Rayleigh number and nanofluid volume fraction while it is a decreasing function of Hartmann number.
514 citations
TL;DR: In this paper, an analysis of laminar motion of a conducting liquid in a rectangular duct under a uniform transverse magnetic field is presented, and the effects of the duct having conducting walls are investigated.
Abstract: The paper presents an analysis of laminar motion of a conducting liquid in a rectangular duct under a uniform transverse magnetic field. The effects of the duct having conducting walls are investigated. Exact solutions are obtained for two cases, (i) perfectly conducting walls perpendicular to the field and thin walls of arbitrary conductivity parallel to the field, and (ii) non-conducting walls parallel to the field and thin walls of arbitrary conductivity perpendicular to the field.The boundary layers on the walls parallel to the field are studied in case (i) and it is found that at high Hartmann number (M), large positive and negative velocities of order MVc are induced, where Vc is the velocity of the core. It is suggested that contrary to previous assumptions the magnetic field may in some cases have a destabilizing effect on flow in ducts.
378 citations
TL;DR: In this article, a numerical approach was employed to demonstrate nanofluid MHD flow through a porous enclosure, where Darcy law has been employed to model porous medium, radiation impact was included in energy equation.
Abstract: Innovative numerical approach was employed to demonstrate nanofluid MHD flow through a porous enclosure. To model porous medium, Darcy law has been employed. Radiation impact was included in energy equation. The new method (CVFEM) has been employed due to complex shape of porous cavity. Aluminium oxide with different shapes was dispersed in to water. Viscosity of nanofluid changes with Brownian motion impacts. Roles of radiation, buoyancy and Hartmann number on treatment of alumina were displayed. Results prove that convection detracts with augment of magnetic forces. Radiation can reduce the temperature gradient.
374 citations
TL;DR: In this paper, the authors examined the natural convection in an enclosure that is filled with a water-Al2O3 nanofluid and is influenced by a magnetic field, based upon numerical predictions, the effects of pertinent parameters such as the Rayleigh number (103,≤,Ra,≤ 107), the solid volume fraction (0.06), and the Hartmann number ( 0.1), on the flow and temperature fields and the heat transfer performance of the enclosure were examined.
Abstract: This paper examines the natural convection in an enclosure that is filled with a water-Al2O3 nanofluid and is influenced by a magnetic field. The enclosure is bounded by two isothermal vertical walls at temperatures Th and Tc and by two horizontal adiabatic walls. Based upon numerical predictions, the effects of pertinent parameters such as the Rayleigh number (103 ≤ Ra ≤ 107), the solid volume fraction (0 ≤ ϕ ≤ 0.06) and the Hartmann number (0 ≤ Ha ≤ 60) on the flow and temperature fields and the heat transfer performance of the enclosure are examined. Prandtl number is considered to be Pr = 6.2. The results show that the heat transfer rate increases with an increase of the Rayleigh number but it decreases with an increase of the Hartmann number. An increase of the solid volume fraction may result in enhancement or deterioration of the heat transfer performance depending on the value of Hartmann and Rayleigh numbers.
358 citations
TL;DR: In this paper, the influence of an external magnetic field on ferrofluid flow and heat transfer in a semi annulus enclosure with sinusoidal hot wall is investigated and the governing equations which are derived by considering the both effects of FHD and MHD (Magnetohydrodynamic) are solved via CVFEM (Control Volume based Finite Element Method).
Abstract: In this paper, influence of an external magnetic field on ferrofluid flow and heat transfer in a semi annulus enclosure with sinusoidal hot wall is investigated. The governing equations which are derived by considering the both effects of FHD (Ferrohydrodynamic) and MHD (Magnetohydrodynamic) are solved via CVFEM (Control Volume based Finite Element Method). The effects of Rayleigh number, nanoparticle volume fraction, Magnetic number arising from FHD and Hartmann number arising from MHD on the flow and heat transfer characteristics have been examined. Results show that Nusselt number increases with augment of Rayleigh number and nanoparticle volume fraction but it decreases with increase of Hartmann number. Magnetic number has different effect on Nusselt number corresponding to Rayleigh number. Also it can be found that for low Rayleigh number, enhancement in heat transfer is an increasing function of Hartmann number and decreasing function of Magnetic number while opposite trend is observed for high Rayleigh number.
355 citations