Computational Fluid Dynamics (CFD) techniques are used to model and simulate the gas flow in the proximity of the melt nozzle exit for a convergent-divergent, close-coupled gas atomiser. After simulating a reference case, several modifications are introduced in the geometry of the atomiser. These geometric changes involve the gas impingement angle, the melt nozzle protrusion length, the design of the divergent zone of the gas nozzle and the coupling distance of the gas exit with respect to melt exit. The simulation results show how the design parameters modify the size of the recirculation zone and the position of the stagnation point. In some cases, it is observed the detachment of the supersonic gas flow from the sidewalls of the melt nozzle, creating a subsonic upward flow that may explain the occurrence of lick-back. The provided information is relevant to optimize the geometrical design of close-coupled gas atomisers.