Study of effect of magnetic field on the axisymmetric vortices produced by a novel vortex generator in a rectangular channel using dynamic mode decomposition

Abstract

The introduction of a magnetic field greatly influences the nanofluid flow in a channel. The current study uses a novel vortex generator (VG) to produce a couple of axisymmetric vortices behind the VG at Re = 6000. These vortices are significantly affected by the strength of the magnetic field. The considered cases are identical and vary only with the change in intensity of the magnetic flux. Initially, at Ha = 5, both vortices P1 and P2 are stretched; however, vortex P2 is stretched significantly in comparison to vortex P1. Such stretching enhances the rotational speed of the vortices resulting in the increment of the overall heat transfer rate by 7.1%, when compared to the case with no magnetic flux. With the increase in magnetic flux, the produced vortices are stretched to such an extent that results in the loss of the majority of its span, leading to the decrement in heat transfer rate from the heated base plate to the flowing fluid. For Ha = 50, the heat transfer rate registers a loss of about 45.4%. Finally, the study of the dynamic mode decomposition reveals that the first dominant mode is 10 times higher than the second and third dominant modes.