Flows, curl of electromotive force, and induced magnetic field in the loop structure of Chen et al. (2014, 2015). The vertical cuts are perpendicular to the loop in the y-z plane at x ≈ 75 Mm (panel a) and along the loop in the x-z plane at y ≈ 30 Mm (panels b–d) as indicated by the vertical lines in the corresponding cuts. Panels a,b show the velocity u in, the arrows indicating the components within the plane, and the color of the component out of the plane. Panel c shows curl of the electromotive force in the x direction [∇ × (u × B)] _x color-coded in the x-z plane. Panel d displays the induced magnetic field , color-coded for the x component and the arrows showing the vectors in the x-z plane. The yellow contours in panelsa–c indicate the levels of 2.5,3,4 G for . We refer to Sect. 3.4.