A numerical study of rotating flow past an axisymmetric obstacle in a cylindrical tube is described. Long nonlinear inertial waves propagate upstream of the obstacle even when the theoretical speed of long waves as given by the linearized equations is equal to the incoming axial flow speed. This occurs when the upstream swirling velocity field is of the Brugers vortex type and the quadratic nonlinear term in the forced KdV equation is not zero. If the flow has a rigid-body rotation, so that the quadratic nonlinear term vanishes, the nonlinear correction of the wave speed is small and cannot be identified even after large times of evolution.