Numerical 3-D Simulations of the Collapse of Photospheric Flux Tubes

Abstract

The interaction of photospheric granular convection with a small scale magnetic field has been simulated numerically in a three-dimensional model, with an extension of techniques recently used to simulate field-free granulation. The evolution of an initially homogeneous magnetic field was followed numerically, both in a kinematic (weak-field limit) description, and in a dynamic description, where the back-reaction of the field on the motion through the Lorentz force is taken into account. The simulations illustrate the strong tendency for the field to be swept up and concentrated in the inter-granular lanes because of the topology of the granular flow. The convectively unstable stratification allows field concentration up to a kilogauss field because the temperature reduction in the magnetic plasma.