Effects of magnetic field on micro cross jet injection of dispersed nanoparticles in a microchannel
International Journal of Numerical Methods for Heat & Fluid Flow
ISSN: 0961-5539
Article publication date: 7 September 2019
Issue publication date: 30 April 2020
Abstract
Purpose
Water/Al2O3 nanofluid with volume fractions of 0, 0.3 and 0.06 was investigated inside a rectangular microchannel. Jet injection of nanofluid was used to enhance the heat transfer under a homogeneous magnetic field with the strengths of Ha = 0, 20 and 40. Both slip velocity and no-slip boundary conditions were used.
Design/methodology/approach
The laminar flow was studied using Reynolds numbers of 1, 10 and 50. The results showed that in creep motion state, the constricted cross section caused by fluid jet is not observable and the rise of axial velocity level is only because of the presence of additional size of the microchannel. By increasing the strength of the magnetic field and because of the rise of the Lorentz force, the motion of fluid layers on each other becomes limited.
Findings
Because of the limitation of sudden changes of fluid in jet injection areas, the magnetic force compresses the fluid to the bottom wall, and this behavior limits the vertical velocity gradients. In the absence of a magnetic field and under the influence of the velocity boundary layer, the fluid motion has more variations. In creeping velocities of fluid, the presence or absence of the magnetic field does not have an essential effect on Nusselt number enhancement.
Originality/value
In lower velocities of fluid, the effect of the jet is not significant, and the thermal boundary layer affects the entire temperature field. In this case, for Hartmann numbers of 40 and 0, changing the Nusselt number on the heated wall is similar.
Keywords
Citation
Bagherzadeh, S.A., Jalali, E., Sarafraz, M.M., Ali Akbari, O., Karimipour, A., Goodarzi, M. and Bach, Q.-V. (2020), "Effects of magnetic field on micro cross jet injection of dispersed nanoparticles in a microchannel", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 30 No. 5, pp. 2683-2704. https://doi.org/10.1108/HFF-02-2019-0150
Publisher
:Emerald Publishing Limited
Copyright © 2019, Emerald Publishing Limited