Interactions of convecting magnetic loops and arcades

Interactions of magnetic loops and arcades that are convecting at their photospheric footpoints are investigated by means of a three-dimensional magnetohydrodynamic simulation. The initial magnetic field is given by solving the bipolar potential field emerging from paired convection holes on the photospheric plane under which magnetic fluxes are supplied. Simulations are performed for single bipolar flux tubes and twin bipolar flux tubes with looplike and arcade-like shapes. It is found that a prominent energy release can occur only when two flux tubes collide and reconnect with each other. The releasing feature becomes more intensive and narrowly peaked as resistivity becomes smaller, which reflects the nature of driven reconnection. A single loop or arcade does not exhibit any significant energy release, even though it is highly twisted and expanded.