Numerical simulation on FSI characteristics of fluid-conveying straight pipe by finite integration method

Based on the four-equation model of the elastic fluid-conveying straight pipe, the axial coupling vibration characteristics with water hammer effect are studied in this paper. Two numerical schemes were developed by combining the finite integration method (FIM) with the implicit Euler method (IEM) and with the numerical inversion of Laplace transform (NILT), respectively, to efficiently and accurately analyze the axial coupling vibration of the pipe. A mixed function, consisting of the radial basis function (RBF) and the polynomial basis function (PBF), is adopted to construct the interpolation function of the FIM at each node. Then, the integral value of a function can be discretized into linear combinations of the function values at the node. This feature makes the FIM easy to program, straightforward and efficient when it is applied to a complicated computational region. To evaluate the accuracy and robustness of the proposed scheme for dealing with the discontinuous wave problems, it was compared with other numerical methods and reasonable agreements were achieved. It indicates that FIM can accurately capture the nonlinear process with water hammer effect. Nevertheless, on processing the temporal term, the numerical oscillation occurs at the discontinuity for NILT while IEM does not have. Moreover, when considering the interaction of Poisson and connection coupling, the pipe pressure wave appears to have some delay in the phase compared with the classic water hammer. Due to the superposition of the pipe vibration and the forced vibrations produced by liquids, the pressure fluctuation increases significantly compared with the situation when only considering Poisson coupling. © 2019, Nanjing Univ. of Aeronautics an Astronautics. All right reserved.