Spectra and pseudospectra for pipe Poiseuille flow Original Research Article

Numerically computed spectra and pseudospectra are presented for the linear operator that governs the temporal evolution of infinitesimal perturbations of laminar flow in an infinite circular pipe at Reynolds numbers 1000, 3000 and 10 000. The spectra lie strictly inside the stable complex half-plane, but the pseudospectra protrude significantly into the unstable half-plane, reflecting the large linear transient growth that certain perturbations may excite.