  The physics of a twisted magnetic flux tube rising in a stratified medium is
studied using a numerical MHD code. The problem considered is fully
compressible (no Boussinesq approximation), includes ohmic resistivity, and is
two dimensional, i.e., there is no variation of the variables in the direction
of the tube axis. We study a high plasma beta case with small ratio of radius
to external pressure scaleheight. The results obtained can therefore be of
relevance to understand the transport of magnetic flux across the solar
convection zone.
