I fully agree if the boundary condition is v=0... I just don't see why that boundary condition has to apply. I guess I just don't understand this fluid shear thing at the boundary... it seems fair enough if the interaction between the fluid and wall is strong, eg. for highly viscous fluids at high velocities, just doesn't seem like its correct for low velocity gas flow next to an almost frictionless surface (coefficient of friction should be negligible). If you think about blowing through a horn, you wouldn't expect the air flow to be just along the central axis, you expect it to move along the surface.
Ah well, at least we can agree that the pipe shouldn't be too small :)