Comparison of the coronal evolution obtained from the two different models of the unsheared arcade (Sect. 4.1), in response to the non-uniform coronal heating pulse. The panels show the coronal averaged temperature and density as functions of time, at four different positions across the magnetic field. The various solid curves represent the HD TRAC solution at these different transverse locations (with the lines colour coded in a way that reflects the distance across the field from the centre of the arcade) and the dashed blue curves correspond to the MHD TRAC solution at these locations.