An isogeometric boundary element method for liquid sloshing in the horizontal eccentric annular tanks with multiple porous baffles

摘要

Boundary element method (BEM) coupled with the isogeometric boundary based on Non-Uniform Rational B-Splines (NURBS), which is termed IGABEM, is a new numerical method and has attracted wide attention in recent years. In this paper, IGABEM is first applied to the liquid sloshing problem in the horizontal rectangular, circular or elliptical annular tanks with multiple porous baffles, assuming incompressible, irrotational and inviscid flows. As a key improvement compared with the conventional polynomial shape function in BEM, the IGABEM for the analysis of liquid sloshing can exactly represent the geometry no matter how coarse discretize the studied boundary, which then produces no geometrical errors. A zoning method is carried out to study arrangement of the multiple porous baffles in the tanks. Neighboring zones is joined together by the boundary conditions of the porous baffles and virtual interface which correlate the flux and velocity potential By discretizing boundaries of each zone using the isogeometric function, the governing integral equation on the boundary by using BEM can be formulated into the dynamic equation in frequency domain. Three configurations of baffles are taken into account such as the top-mounted baffles, bottom-mounted baffles and annular baffles. The results obtained by the proposed method are verified by comparing with the reported solutions and very good agreement is obtained. The effects of tank's geometry, liquid filling level and the baffle's parameters with various lengths, submergence depths, number of baffles, and porosities on the natural sloshing frequency, wave surface elevation, sloshing force and velocity field are investigated and several conclusions are achieved.