In this addendum, supplemental to recently reported work on centrifugal separation of natural gas, we consider the effect of nonzero convective flow, which we had previously neglected as it had been assumed to be nearly zero. Here, we show that it is not necessary to assume that convective flow is zero, which also leads to the conclusion that, contrary to what we stated earlier, the pressure distribution changes during the diffusion of components to centrifugal equilibrium.