  The combined effects of imposed vertical mean magnetic field (B0) and
rotation on heat transfer phenomenon driven by the Rayleigh-Taylor instability
are investigated using DNS. In the hydrodynamic (HD) case (B0 = 0), as the
rotation rate f increases from 4 to 8, the Coriolis force suppresses the growth
of mixing layer height (h) and u3', leading to a reduction in heat transport.
The imposed B0 forms vertically elongated thermal plumes that exhibit larger
u3' and efficiently transport heat between hot and cold fluid. Therefore, we
observe an enhancement in heat transfer in the initial regime of unbroken
elongated plumes in f=0 MHD cases compared to the corresponding HD case. In the
mixing regime, the flow is collimated along the vertical magnetic field lines
due to imposed B0, resulting in a decrease in u3' and an increase in growth of
h compared to f=0 HD case. This increase in h enhances heat transfer in the
mixing regime of f=0 MHD over the corresponding HD case. When rotation is added
along with imposed B0, the growth and breakdown of vertically elongated plumes
are inhibited by the Coriolis force, reducing h and u3'. Consequently, heat
transfer is also reduced in rotating MHD cases compared to corresponding f=0
MHD cases. The heat transfer in rotating MHD cases remains higher than in
corresponding rotating HD cases. This also suggests that B0 mitigates the
instability-suppressing effect of the Coriolis force. The t.k.e. budget reveals
the conversion of t.k.e., generated by the buoyancy flux, into t.m.e..
