Numerical simulation of scaling intake duct was carried out for the purpose of exploring the source and aerodynamic characteristic of ground vortex under crosswind condition. Results showed that trailing vortex and ambient vortex were both the major contributions to the production of ground vortex under 90 degree crosswind condition. Even though there was no ambient vorticity

ground vortex could still be there under 90 degree crosswind condition as illustrated by the trailing vortex-ground vortex model. Vorticity of ground vortex increased to the maximum and then decreased with the increase of approaching flow velocity while the critical velocity ratio increased with the increase of height-to-diameter ratio. While the height-to-diameter ratio was doubled

the critical velocity ratio increased by 65% and the peak vorticity of ground vortex decreased by 30%. Total pressure loss of the intake duct increased with the decrease of approaching flow velocity ratio due to either ground vortex or flow separation.