w(/s)	Amplitude (cm)	Mean flow oscillation period(min)
0.39	13	45
0.4	12	70,90,120(Flow decreases and do not reverse)
0.4	13	50,55,55,70,80,80,90
0.42	13	80

Figure 10 The periods of the mean flow oscillation. Amplitude is that of the wave generator's piston. The period is measured by observing the flow at a fixed point.