Mode-switching was investigated when water was poured into a cup, Three modes, i.e., accumulation flow (Mode I), scattering flow (Mode II), and oscillatory flow (Mode III), were regulated by the flow rate. The bifurcation flow rate at Mode I --> II was different from that at Mode II --> I, i,e., hysteresis in mode-switching was observed. Mode III was observed at Mode I --> II, The bifurcation point changed depending on the radius of the water tube, and the waterhollow was an important factor in mode-switching. The mode-switching was reproduced by a numerical calculation including the double-minimum profile of the free energy and the flow rate. (C) 2002 Elsevier Science B.V. All rights reserved.