Time evolution of the gas fraction of the dwarf galaxy h159 evolving through a wind tunnel simulation (see Table 2 for the list of parameters). Left panel: hot gas fraction contained in one virial radius. Right panel: cold gas fraction contained in 0.1 virial radius. The colour of each line reflect the corresponding β_t. In both panels, the green and black lines correspond to the isolated and fiducial wind tunnel model respectively. A moving average has been applied with a gaussian kernel (standard deviation of ∼100 Myr in a window of −500 to 500 Myr) to reduce the noise. Due to this filter, the earliest times are removed and the different curves start at different fraction.