Evolution of a horizontal scale for magnetoconvection

The nonlinear modal equations governing magnetoconvection in a fluid layer have been integrated forward in time incorporating a discrete spectrum of horizontal wave numbers, distributed within the range supporting convection. By progressively deleting some of the decaying modes and introducing additional modes within the range of growth it is possible to establish the evolution, or otherwise, of a preferred horizontal scale, which determines the horizontal cell size of the convective motions. Further, the influence of the magnetic field strength on cell extent can also be determined.