Within a gearbox the majority of transmission losses can be attributed to bearing losses, meshing losses or losses due to windage/churning. In this paper the commercial CFD code Fluent 6.2.16 is applied in a 2D study of windage power loss (WPL) from a single spur gear rotating in air. By comparing CFD data to published experimental data appropriate grid density and modelling parameters are identified. The model is used to investigate how peripheral shrouding affects WPL and whether WPL can be reduced through minor modifications to tooth tip geometry.Non-dimensional shroud spacings (ratio of gap to gear PCD) of between 0.005 and 0.05 were investigated at shaft speeds between 5,000 rpm and 20,000 rpm. Although CFD data compared reasonably well to experimental data, trends were not reproduced and an optimum shroud could not be identified. A full 3D study is recommended.Modifying the tooth tip by adding a small chamfer on the leading edge reduced WPL by approximately 6%. A small fillet increased total WPL by a similar amount suggesting that WPL may increase as a gear wears. This preliminary study suggests further work in this area would be beneficial.