Coupled structure (FE) and fluid flow (FV) analysis for vortex induced vibrations

摘要

Fuel elements or any other tubular structure submerged in a fluid tank may be excited by seismic loadingrngenerating resonating response of vortex induced vibrations. High-speed interaction between two structures or a structurernand a fluid requires simultaneous modeling of large deformations of structures and shock propagation in fluids. Modelingrnof varying flow regimes and boundary conditions in fluids is better managed by finite volumes, however, modelling ofrnstructural deformations is usually better done with finite elements. However, until now, available softwares have beenrnusing exclusively one of the two methods to model both fluids and structures, fluidyn-FSI, probably the onlyrncommercially available software of its kind. offers simultaneous use of both structures finite elements (for structures) andrnfinite volumes (for fluid) formulations implemented inside the same solver.rnA validation analysis has been done to simulate the structural deformations, modeled in finite elements andrncoupled in time domain with the surrounding fluid flow in finite volumes. The results in the Reynolds number range ofrn1000 to 125000 have been compared with the published experimental in-line and cross-line frequencies as well as dragrncoefficients although only results at Re = 1000 are shown here. The Strouhal number is also found to be very close to thernestimates. The demonstrated software capability to adapt the fluid mesh to the displacements of the structure allows tornkeep a relatively low mesh density in the strong gradients zones, such as vortices and the boundary layer around therncylinder, thus ensuring a better precision of the results.rnThe same studies carded on for other kind of cylinders (square or variable cross-section) and for other flowrnconfigurations have shown similar results. The use of a solver capable of strong coupling between the fluid model andrnthe structure model remains the best way to approach the modelisation of these phenomena. The coupled approach isrnmade available for general usage influidyn-FSI software platform and has been used for other applications.