Density (left panel) and flow velocity (right panel) are displayed as functions of time (t/t_A) and distance along the thread (s/L). Each plot combines an image (bottom), a surface plot (middle), and a contour plot (top) of the corresponding quantity. Density is normalised with respect to its initial value, ρ₀. The velocity of the flow is normalised with respect to initial Alfvén speed, c_A0.