The mixing characteristics of external flow with jets from five rectangular nozzles with aspect ratio of 1
4
8
12
16 and from an axisymmetric nozzle were studied numerically.All nozzles studied had equal exit area.The results show that the rectangular nozzles lead to a relatively shorter jet core region and faster velocity and temperature decay rate than the axisymmetric one on centerline.This trend increases with the increase of aspect ratio.