The effects of external magnetic fields on the flow and heat transfer in a three-dimensional microchannel

Abstract

In this study, the thermal and flow characteristics in a U-type microchannel have been investigated and compared under the influence of single and combined magnetic fields. The effects of various Reynolds numbers $(\mathrm{Re}=50-1000),$ Hartmann numbers $(\mathrm{Ha}=0-80),$ and nanoparticle volume fractions $\left(\mathrm{\varnothing }=0.01-0.04\right)$ are examined. It is found that selecting the appropriate arrangement of applying single and combined magnetic fields plays an essential role in microchannel thermal performance and fluid flow behavior. Under the influence of some combined magnetic fields, a secondary flow is applied to the primary flow and affects the flow and heat transfer. The Nusselt number under the influence of the applied magnetic field(s) increases up to 137.7% or even decreases down to 25.5% compared to that without the magnetic field for various conditions. Results show that the combined magnetic fields usually provide better thermal performance than that of the single one.

Keywords:

• Magnetic field configuration
• nanofluids
• secondary flow
• thermal performance
• U-type microchannel

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.