Examples of the effects on the spiral perturbation when changing (increasing) the different parameters in the model. Panel A: spiral perturbation for a certain set of parameters. This is taken as the default for the comparison in this figure. Panel B: spiral perturbation with an increased linear winding parameter. Panel C: spiral perturbation with an increased quadratic winding parameter. We note that the inner part of the spiral is still similar to panel A. Panel D: spiral perturbation with an increased phase angle, rotating it half a revolution. Panel E: spiral perturbation with an increased scale factor, which increases the V_Z–Z axis ratio. Panel F: spiral perturbation with the flattening function distance increased, which makes the inner parts less distinct.