Undertaking a dynamic "nite element analysis on a tank containing a #uid either requires both the #uid and tank to be modelled or the mass of the vessel's walls and base to be adjusted to account for the presence of the #uid. The former generally requires specialized solid elements to model the #uid, which are not available in all "nite element software packages. This paper details a set of properties for structural solid elements that allow these elements to accurately emulate water within a vessel. Two fully welded rectangular steel tanks, constructed from plate of di!erent thicknesses, were partially "lled with water and dynamically excited. Excellent agreement was found between the dynamic measurements taken from the base of the tanks and the predictions from a "nite element model with the #uid modelled using structural solid elements and the derived property set. These experiments show that the fundamental mode of dynamic behaviour of the base of these tanks is primarily dependent on both the depth of #uid in the tank and the thickness of its base. The added mass principle of Greenspon (Journal of Acoustical Society of America 33, 1485}1497 [1]), derived mainly for plates exposed to essentially an in"nite body of #uid, could not be used to accurately calculate the adjustment in mass of the base plate to account for the presence of a "nite volume of #uid. A modi"cation to the added mass principle of Greenspon has been proposed that fully accounts for this depth and base thickness dependency.
2001 Academic Press