Wake induced drag survey
The sweep-plane is coloured by the integrand of the momentum+pressure integral, so it shows the local contribution to the induced drag force on the finite wing (an inviscid source of drag). Clearly the tip vortices are the largest sources of drag due to the deficit of streamwise momentum in their locality (most of the flow there is in-plane swirl which also causes reduced pressure further increasing the drag). The region within the wake sheet also contributes to the drag due to the induced downwash created by the tip (and also starting) vortices. The blotchy nature of the solution near the wake sheet filaments is an artifact of the low order nature of the vortex lattice method, as well as the low resolution of the wake sheet. However the drag values obtained using this wake survey method compare well to the equivalent calculation using the surface pressure forces on the wing (actually they are even better for small angles of attack). This wing was at 15 degrees AOA.
The sweep-plane is coloured by the integrand of the momentum+pressure integral, so it shows the local contribution to the induced drag force on the finite wing (an inviscid source of drag). Clearly the tip vortices are the largest sources of drag due to the deficit of streamwise momentum in their locality (most of the flow there is in-plane swirl which also causes reduced pressure further increasing the drag). The region within the wake sheet also contributes to the drag due to the induced downwash created by the tip (and also starting) vortices. The blotchy nature of the solution near the wake sheet filaments is an artifact of the low order nature of the vortex lattice method, as well as the low resolution of the wake sheet. However the drag values obtained using this wake survey method compare well to the equivalent calculation using the surface pressure forces on the wing (actually they are even better for small angles of attack). This wing was at 15 degrees AOA.