Effect of vortex promoter shape on heat transfer in MHD duct flow with axial magnetic field

The heat transfer from the side-wall of a duct through which an electrically conducting fluid flows within a strong transverse magnetic field is numerically investigated using high-resolution numerical simulation. Parameter ranges considered are 0≤Ha≤2400 and 100≤Re≤3000 for a constant blockage ratio of 1/4. The gain in the heat transfer using obstacles of different geometric shapes are compared. For Ha=320, a maximum heat transfer enhancement of 78% is obtained when using the square cylinder at a modes Re=1000, while the triangular cylinder outperformed the various other vortex promoter geometries at Re = 2000 yielding a 75% improvement. However, at a higher Hartmann number of Ha=2400, a maximum heat transfer augmentation of 16% and 40% is obtained for the triangular cylinder at Re=1000 and 2000, respectively. This suggests that for a duct flow under the influence of a strong magnetic field, the triangular obstacle is a superior heat transfer promoter geometry compared to the square or circular cylinders. A further net power analysis reveals that the heat transfer enhancement dominates over the pumping power to produce net benefits for even a modest heat transfer enhancement.