Approximations to sloshing frequencies for rectangular tanks with internal structures

The frequencies of free oscillation of a fluid in a rectangular tank are reduced by the introduction of a rigid internal structure. This paper gives general, approximate methods for the calculation of the oscillation frequencies when the structure is a cylinder of arbitrary cross section spanning the tank, and with generators normal to one pair of vertical faces. Particular results are given for submerged, circular cylinders and both vertical and horizontal thin baffles.