Case n = 1. Bidimensional representation of the self-similar spiral pattern for T₀ = 0.17, leading to values of B = tanθ equal to ≃1.0 and θ equal to about 45 deg. The yellow line corresponds to the trajectory of a fluid particle, the red circle shows a circular orbit that the same fluid particle would have in a symmetrical disc. The trajectory of the fluid particle shows that while the fluid particle has a non-circular orbit, it is nevertheless closed. This is because the mass flux vanishes. There is an outwards flux of angular momentum, however.