Temporal variations of (a) p(t) and (b) ∂p(t)/∂t at several observation points in the conduit and reservoir system in Model I. See Fig. 1 for locations of observation points. Small-amplitude high-frequency oscillations observed near the ends of the signals at P03, P05, P07, and P09 are numerical artefacts caused by the sharp corner between the conduit and reservoir. The starting times in (a) and (b) are arbitrary.