[KamperBob]

AND the template applies only down centerline (vertical plane of symmetry lengthwise). Away from centerline sides play a role. It's a 3D problem. If the sides taper more quickly then the top, air flows over top and down the sides to fill. If top drops more quickly than the sides slope, air flows up the sides and over top to fill. Flow will establish its equilibrium. Equations will balance. Even without boundary layers, simpler pressure/flow CFD should help here. Tufts help and are more approachable technology.