bottom frame is for the corresponding vertical field case $\theta=0^\circ$ (for which $\phi$ is irrelevant). The full vertical lines indicates the location of the $a=c$ equipartition height, and the vertical dashed line shows the position of the stochastic driving plane.[]{data-label="fig:FzVz"}](figures/fz_th0ph80_5mHz_1kG "fig:"){width=".75\hsize"}

Figure \[fig:FzVz\] shows how the acoustic, magnetic, and total fluxes vary with height in two representative cases, the first with highly inclined magnetic field and the second with vertical field. Most fluxes have settled quite well to their asymptotic states by about $z_f=1.2$ Mm, indicating that our computational box is (for the most part) tall enough. There is also clearly a transfer of energy flux from acoustic to magnetic in the inclined field case over several hundred kilometres above $a=c$, as expected [@CalHan11aa]. This is absent in the vertical field case, as there the fast and Alfvén waves are decoupled.

Another reason for the (moderate) differences between the flux maps presented here and those of @CalGoo08aa is the different way that waves are injected from below. In @CalGoo08aa, care is taken to inject only a pure fast wave at $z=-4$ Mm, where it is overwhelmingly acoustic. Any magnetic wave at the top of the computational box could therefore have 