Case n = 1 / 2. Bidimensional representation of the self-similar spiral pattern for a temperature of T₀ = 0.17 leading to values of B = tanθ equal to 1 and to a value of 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. Fluid particles are found to spiral inward because of dissipation.