Experimental Study on the Frequency of a Free Surface Fluctuation in a Vessel With or Without an Internal Structure

An experimental study has been performed to investigate the frequency of a free surface fluctuation in a vessel with and without an internal structure. Water flows in from the bottom nozzle and flows out at the side wall nozzles. There are two dominant frequency regions which are generated by a standing wave and a jet. In the standing wave region, the frequency is well described by f(4πd_V/g)^1/2 = 1.07 in a circular vessel. The frequency generated by a jet can be described by a dimensionless period and Froude number according to its fluctuation stability. In the case of a vessel with an internal structure, it needs a geometry factor which is described by a vessel diameter to a hydraulic diameter ratio in a standing wave region.