Run A3. Evolution of the main dynamical terms (solid and dashed blue lines), their resultant (black line), and the velocity field (dash-dotted orange line, different scale), along both x (left panels) and y (right panels). The 1D cuts are taken at half domain (i.e. they intersect the flux rope axis). All the quantities are in code units and the dynamical terms are re-scaled relative to their maximum at t = 0. Only the right half of each 1D spatial domain is shown, since the dynamics is just inverted in the other half (axial symmetry). The computed (expected) pinch tracer size is shown as a filled light pink region (vertical line) for each snapshot. In the bottom right corner of each panel, an inset shows the resultant acceleration, ${\dot{u}}_{x,y}$, as a black line filled with red or cyan according to its positive or negative sign.